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• Bitbucket SSH and iptables

  - by Astaz3l

  I'm a newbie in iptables to be honest. I have some basic rules. Everything is blocked by default. iptables -t filter -F iptables -t filter -X iptables -t filter -P INPUT DROP iptables -t filter -P FORWARD DROP iptables -t filter -P OUTPUT DROP iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT ...some rules for http, ftp etc... iptables -t filter -A OUTPUT -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -t filter -A INPUT -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT With the last two lines i'm trying to open the access for ssh so i can connect to bitbucket. When i try to connect to bitbucket: ssh -Tv [email protected] I got the error - connection timed out. But when I disable iptables i can connect without any problems. What am i missing? Should I add any additional rules?

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• Which full-text search package should I use for SQLite3?

  - by Benjamin Pollack

  SQLite3 appears to come with three different full-text search engines, called FTS1, FTS2, and FTS3. The documentation available on the website mentions that FTS1 is stable, FTS2 is in development, and that you should use FTS2. Examples I find online use FTS3, which is in CVS, and not documented versus FTS2. None of the full-text search engines come with the amalgamated source, as near as I can tell. So, my question: which of these three engines, if any, should I use for full-text indexing in SQLite? Or should I simply use a third-party tool like Sphinx, or a custom solution in Lucene, instead?

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• Creating hard drive backup images efficiently

  - by Arrieta

  We are in the process of pruning our directories to recuperate some disk space. The 'algorithm' for the pruning/backup process consists of a list of directories and, for each one of them, a set of rules, e.g. 'compress *.bin', 'move *.blah', 'delete *.crap', 'leave *.important'; these rules change from directory to directory but are well known. The compressed and moved files are stored in a temporary file system, burned onto a blue ray, tested within the blue ray, and, finally, deleted from their original locations. I am doing this in Python (basically a walk statement with a dictionary with the rules for each extension in each folder). Do you recommend a better methodology for pruning file systems? How do you do it? We run on Linux.

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• Windows Firewall issues

  - by Will Vousden

  I'm not sure whether this is a Windows problem or a .NET problem (i.e. whether it belongs here on on SO), but I've written a small HTTP server program in C# (using the .NET HttpListner class) which works fine for the most part, but Windows Firewall seems to be refusing to let connections through to it from anything other than localhost. I've added exceptions for TCP and UDP in the "Inbound Rules" section of the firewall settings, essentially duplicating existing rules for other HTTP-based services which work fine (e.g. foo_httpcontrol). Specifically, I've added separate rules for TCP and UDP connections covering all ports, specific to the executable I'm running. There's no problem when Windows Firewall is disabled, but if I enable it, the connection simply times out.

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• How to set up port forwarding and firewall settings for torrents using Transmsission on Mac OSX 10.5

  - by Liz

  I have picked up bits of advice here and there on the internet and got someway through this tortuous exercise (after it took 18 hours to download the first torrent I tried yesterday - magnet-link for a film). Where I have got stuck is with configuring the firewall on the Netgear Router but I am not sure if I have caused the problem myself by something else I have done configuring the Mac System Preferences for Security or Networking. I have been following the sections of these instructions that seem to apply, although they are written for a different OSX version (don't know which one, but the screen shots do not match what I see) and I am not wanting to set up my Mac as a server and attending to the parts that apply to port forwarding for Netgear rather than LinkSys: http://homepage.mac.com/car1son/static_port_fwd_intro.html I have been trying to follow these instructions: Instructions for DG834, DG834G, DG824M, FR114W, FM114P, FR114P, FR328S, FVL328, FVS328, FVS338, FVX538, FWAG114, FWG114P, or FVS318v3 These routers do port forwarding by assigning port numbers to a "service" associated with the application you want to run. "Rules" are set for particular services. Rules block or allow access, based on various conditions such as the time of day and the name of the service. To Create a New Inbound or Outbound Rule 1. Submit the router's address in an Internet browser. (The default is 192.168.0.1). 2. Enter the router's username and password. 3. From the main menu, click Security > Rules. 4. Click Add for inbound or outbound traffic, as appropriate to the application you are planning to run. 5. Select the Service. The services the router knows about are listed in the drop down. If the service you want is not listed, add it as described in the next section. 6. Select the Action, for example ALLOW always. 7. For Send to LAN Server, enter the IP address of the local server. Note that this is also the IP address the computers on your LAN will access. 8. For WAN User choose Any, or limit access to particular IP addresses. 9. For Log selection it is reasonable to turn logs on, especially at the beginning when you are unsure of the result of the changes you are making. Later, you may want to set logs to "Never" for performance reasons. 10. Click Apply. As noted in user manual for some models: * Consider using the Dynamic DNS feature on the Advanced menu, so that external users can find your network when the DHCP lease is renewed by your ISP. * If your own LAN server uses DHCP, and your IPs change on rebooting, consider using the Reserved IP Address feature in the LAN IP menu. To Add a Service for These Routers 1. Click Security > Services > Add Custom Service. 2. Enter any name you choose for the service. 3. Select whether the service is to use TCP or UDP. If you are unsure, select both. 4. Enter the lowest port number used by the service. 5. Enter the highest port number used. If the service uses only one port number, enter the same number. 6. Click Apply. There is no "Security - Rules" submenu in the Netgear page, so I have been trying to access "Security - Firewall Rules". I can access everthing else in the Netgear settings as Admin but I cannot get the "Firewall Rules" section to open up. (I am not 100% sure I will know exactly what to do if and when I do get it opened up!) I haven't managed to find though searching the internet any instructions that would seem to apply specifically to what I am trying to achieve, so would be very grateful if someone could either point me in the right direction or give me some advice directly. Best wishes, Liz

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• 2D Spaceship movement math

  - by YAS

  Hi, I'm new here. I'm trying to make a top-down spaceship game and I want the movement to somewhat realistic. 360 degrees with inertia, gravity, etc. My problem is I can make the ship move 360 with inertia with no problem, but what I need to do is impose a limit for how fast the engines can go while not limiting other forces pushing/pulling the ship. So, if the engines speed is a maximum of 500 and the ship is going 1000 from a gravity well, the ship is not going to go 1500 when it's engines are on, but if is pointing away from the angle is going then it could slow down. For what it's worth, I'm using Construct (www.scirra.com), and all I need is the math of it. Thanks for any help, I'm going bald from trying to figure this out.

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• Iptables massive 1:1 NAT

  - by TiFFolk

  I have to connect two LANs: LAN1: 10.10.0.0/16 and LAN2: 192.168.0.0/16. I can't do simple routing, because 192.168.0.0/16 net is prohibited in LAN1, so I am thinking of using Full cone nat (1:1) to translate 192.168.x.y/16 to 10.11.x.y/16. Each translation is done by this rules: iptables -t nat -A PREROUTING -d 10.11.0.0/16 -j DNAT --to-destination 192.168.0.0/16 iptables -t nat -A POSTROUTING -s 192.168.0.0/16 -j SNAT --to-source 10.11.0.0/16 But I will have to enter 254*254*2 rules, what will, I think, result in enormous performance degradation. So, is there a way to write such one-to-one translation with minimum number of rules?

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• How do I compile mercurial 1.5.2 on debian?

  - by Aaron Digulla

  I downloaded the files for Mercurial 1.5.2 from http://packages.debian.org/sid/mercurial (mercurial_1.5.2-1.debian.tar.gz, mercurial_1.5.2-1.dsc and mercurial_1.5.2.orig.tar.gz). How do I get a .deb package out of these? I tried to follow the instructions at http://www.debian.org/doc/maint-guide/ch-build.en.html but they don't work. I tried to unpack the two archives and run dpkg-buildpackage or debian/rules build but that fails with: dh --with quilt clean dh_testdir debian/rules override_dh_auto_clean make[1]: Entering directory `/home/user/packages/mercurial-deb' cp -a mercurial/__version__.py mercurial/__version__.py.save cp: cannot stat `mercurial/__version__.py': No such file or directory make[1]: *** [override_dh_auto_clean] Error 1 make[1]: Leaving directory `/home/user/packages/mercurial-deb' make: *** [clean] Error 2 That's because the directory mercurial is inside mercurial_1.5.2/. Why doesn't the build script cd into the right place? If I try ../debian/rules build, I get dh --with quilt build dh: cannot read debian/control: No such file or directory sigh How do I compile a package for debian???

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• Dynamic procmail filters

  - by WombaT

  i need procmail to place incoming mail into specific folder depending on some set of rules. I know how i can accomplish this, but i need to write static set of rules in a specific file. What i really need is to configure procmail to use rules stored in mysql database. How i can do this? I've read a bit about that and one solution i found is to pipe message to a php/perl script and return a folder name to place message. But i have completely no i idea how to use php script as a rule and then use its return value.

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• Firewalling a Cisco ASA Split tunnel

  - by dunxd

  I have a Cisco ASA 5510 at head office, and Cisco ASA 5505 in remote offices. The remote offices are connected over a split tunnelled VPN - the ASA 5505s use "Easy VPN" Client type VPN in Network Extension Mode (NEM). I'd like to set firewall rules for the non-tunnelled traffic only. Traffic over the VPN to head office should not have any firewall rules applied. I might want to apply different firewall rules to different remote offices. All the documentation I have been able to find assumes the Client VPN is a software endpoint, and all the configuration is done at the 5510. When using a Cisco 5505 as the VPN client, is it possible to configure any firewalling at the Client end, or does it all have to come from the 5510? Are there any other issues to look out for when split-tunnelling a VPN by this method?

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• Altq limits not being applied to UDP transfers

  - by overkordbaever

  I have a OpenBSD server acting as a router/firewall with yhr packet filter ruleset shown below, a linux server, and a linux client. When transferring files (using netcat) by TCP, the limits are applied (for example the 100mbit limit in the example), though when transferring data by UDP, the limits aren't applied; the file always takes the same amount of time no matter the queue bandwidth limit I set (I can even turn off the queues completely, and will still get the same result). Why aren't the queuing rules applied to UDP packages? The rules used: #queue rules altq on { $int_if, $ext_if } cbq bandwidth 100Mb queue { def, low } queue def bandwidth 0Mb cbq(default) queue low bandwidth 100Mb cbq #Passrules test pass out quick from $int_if to $ext_if queue low pass in quick from $ext_if to $int_if queue low pass out quick from $ext_if to $int_if queue low pass in quick from $int_if to $ext_if queue low I suppose this may be related a question I've previously asked, though since it's more of a separate question, I suppose a separate question should be used for this

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• How to configure Amazon Security Groups to achieve multi-tier architecture?

  - by ks78

  What is the preferred way to configure Amazon Security Groups to achieve a multi-tier architecture? Each of my instances has its own Security Group, which I only want to use for rules specific to an instance. I'd like to keep any rules which apply to multiple instances in a separate Security Group, which can then be assigned to instance Security Groups as necessary. As an example, I've setup a group called "admin", which allows administrative access from my IP. I added the "admin" group as the source to each of my instance security groups. However, I still can't access the instances from my IP without adding the rules directly to the instance's group. Am I missing something? Although it seems a multi-tier security architecture should be possible, it doesn't seem to be working.

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• How to configure Amazon Security Groups to achieve multi-tier architecture?

  - by ks78

  What is the preferred way to configure Amazon Security Groups to achieve a multi-tier architecture? Each of my instances has its own Security Group, which I only want to use for rules specific to an instance. I'd like to keep any rules which apply to multiple instances in a separate Security Group, which can then be assigned to instance Security Groups as necessary. As an example, I've setup a group called "admin", which allows administrative access from my IP. I added the "admin" group as the source to each of my instance security groups. However, I still can't access the instances from my IP without adding the rules directly to the instance's group. Am I missing something? Although it seems a multi-tier security architecture should be possible, it doesn't seem to be working.

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• Cannot acess the new cloned server even after new IP address assignment

  - by tough

  I was able to clone a Ubuntu 10.04 server residing in Cloud. It appeared that I was not getting some IP for the new VM so I followed some of these: # cd /etc/udev/rules.d # cp 70-persistent-net.rules /root/ # rm 70-persistent-net.rules # reboot I didn't follow the later commands as I was unable to see two eth MACs as available in the referenced site. After this I am able to see some the IP for it, and is different form the original IP, I have added new IP to DNS server. Now when I try to access it with its assigned(new) domain it is directed to the old server. I can see both the VMs running with different IP. Where I might have gone wrong, I am new to this admin thing.

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• What is a good solution for an adaptive iptables daemon?

  - by Matt

  I am running a series of web servers and already have a pretty good set of firewall rules set up, however I'm looking for something to monitor the traffic and add rules as needed. I have denyhosts monitoring for bad SSH logins, and that's great - but I'd love something I could apply to the whole machine that would help prevent bute force attacks against my web applications as well, and add rules to block IPs that display evidence of common attacks. I've seen APF, but it looks as though it hasn't been updated in several years. Is it still in use and would it be good for this? Also, what other solutions are out there that would manipulate iptables to behave in some adaptive fashion? I'm running Ubuntu Linux, if that helps.

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• Find users that are auto forwarding / redirecting their email in Exchange 2010 using Powershell

  - by Ryan H

  We are using Live@edu, which is essentially hosted exchange server with some additional features and limitations to work around, and I'm trying to find everybody that is forwarding or redirecting emails from their accounts. I am trying to remove old accounts that have not been used, but we have instructions for users on redirecting emails, so we should expect that some users are indeed redirecting their emails, which will make their last login/logoff times not reflect whether they are indeed using auto forwarding or auto redirecting rules. How could I find a list of users with forwarding or redirection rules using Exchange 2010 Powershell Cmdlets? /EDIT: It may be sufficient for my purposes to find whether there are ANY server side rules, regardless of whether the rule forwards/redirects or does some other action.

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• Combine several locations with regex in nginx

  - by AlexAtNet

  I dynamic number of Joomla installations in subfolders of the domain. For example: http://site/joomla_1/ http://site/joomla_2/ http://site/joomla_3/ ... Currently I have the follwing config that works: index index.php; location / { index index.php index.html index.htm; } location /joomla_1/ { try_files $uri $uri/ /joomla_1/index.php?q=$uri&$args; } location /joomla_2/ { try_files $uri $uri/ /joomla_2/index.php?q=$uri&$args; } location ~ \.php$ { fastcgi_pass unix:/var/run/php5-fpm/joomla.sock; ... } I'm trying to combine joomla_N rules in one: location ~ ^/(joomla_[^/]+)/ { try_files $uri $uri/ /$1/index.php?q=$uri&$args; } but server starts to return index.php as is (does not call the php-fpm). It looks like the nginx stops the processing of the regex rules after the first match. Is there any way to combine this rules with something like regex?

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• CSF Unresolved issue

  - by josephmarhee

  I began receiving service failures for CSF/LFD once the limit was reached in iptables preventing the service from working properly. I flushed all iptables rules, and redid by rules using CIDR rather than the individual IPs that were listed and the issue persists. Error: The VPS iptables rule limit (numiptent) is too low (1527/1536) - stopping firewall to prevent iptables blocking all connections, at line 1459 This is after restarting CSF, which gave me: You have an unresolved error when starting csf. You need to restart csf successfully to remove this warning CSF still seems to be trying to enforce rules that no longer exists (lists entire chains upon trying to be restarted,only to fail with that error). Any idea of what's going on?

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• ESX Firewall Command Troubles

  - by John

  Hi, I am working on creating some firewall rules to stop some of the SSH brute-force attacks that we have seen recently on our ESX server hosts. I have tried the following rules from the CLI to first block all SSH traffic and then allow the two ranges that I am interested in: esxcfg-firewall --ipruleAdd 0.0.0.0/0,22,tcp,REJECT,"Block_SSH" esxcfg-firewall --ipruleAdd 11.130.0.0/16,22,tcp,ACCEPT,"Allow_PUBLIC_SSH" esxcfg-firewall --ipruleAdd 10.130.0.0/16,22,tcp,ACCEPT,"Allow_PRIVATE_SSH" However, these rules are not working as intended. I know that if you do not enter the block rule first, then the allow rule will not be processed. We are now having the issue where the first entered allow rule is being ignored such that the block rule works and the last entered allow rule works. I was curious if anyone had any ideas on how I could allow a few different ranges of IP's with the esxcfg-firewall --ipruleAdd command? I am at a loss and am having a hard time locating examples or further documentation about this. Thanks in advance for your help with this.

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• Apache .shared folder

  - by Kevin

  There are already a bunch of rules in my Apache configuration. What I want to add is the following. There are some shared folders (.shared): /var/www/.shared/ and /var/www/.include/.shared/ and /var/www/.include/(.*)/.shared/. Now when someone visits http://domain.com/test.png it first executes the existing apache rules and will (when the file/folder was not found) look in those .shared folders. So suppose I've got this filesystem: /var/www/.shared/dog.png /var/www/.shared/test.gif and /var/www/domain.com/dog.png. Now when someone visits http://domain.com/test.gif, it must load the test.gif from the .shared folder. Now when someone visits http://domain.com/dog.png it must load the dog.png from the domain.com folder (because the existing apache rules will be executed first).

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• Opening a port to make a connection in Windows 7 [closed]

  - by jannes braet

  Possible Duplicate: trouble with opening a port to make a connection I have watched a video on how to open my ports in Windows 7. I followed the example by going to my "firewall" in "advanced settings" and I made new rules in "inbound rules" and in "outbound rules". I chose to allow connections to all ports, but if I try it with canyouseeme, then it says I can't find the configured port. Maybe it is because the site is wrong, but I don't really believe so. Could someone tell me how I open my ports so that I can connect to them and others to connect to them via the internet (if they have my ip-adress of course)?

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• How to configure Unity/Compiz in 12.04 so that Update Manager opens maximized w/screen bigger than 1024×600?

  - by Jani Uusitalo

  In Precise, window auto-maximize is disabled on monitors with a resolution above 1024 × 600 [1]. I have a bigger resolution, but I prefer maximized windows anyway. I want Update Manager to start maximized. What I've tried so far: In Compiz Config Settings Manager, I have Place Windows activated and 'Windows with fixed placement mode' has windows matching the rule "(name=gnome-terminal) | (name=update-manager)" set to 'Maximize'. With this, Gnome Terminal starts maximized, Update Manager does not. In Compiz Config Settings Manager, I have set a Window Rules [2] rule to match "name=update-manager". Irregardless of any rules set or not, activating Window Rules results in not being able to bring out Unity Launcher anymore, Alt+Tab window switching becoming slow or nonfunctional entirely and the screen sporadically freezing completely. Not a viable option apparently. I've installed Maximus [3] and started it. Update Manager ignores it (or vice versa). I've not tried devilspie and would prefer not to. Having to configure something external for this would seem stupidly redundant with (the no-brainer) Maximus and all these Compiz options already available. I just can't seem to make them work. [1] https://bugs.launchpad.net/ayatana-design/+bug/797808 [2] http://askubuntu.com/a/53657/34756 [3] How to configure my system so that all windows start maximized?

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• Oracle Technology Network Virtual Developer Day: Service Oriented Architecture (SOA)

  - by programmarketingOTN

  Register now! Oracle Technology Network Virtual Developer Day: Service Oriented Architecture (SOA) - Discover the Power of Oracle SOA Suite 11gTuesday July 12, 2011 - ?9:00 a.m. PT – 1:30 p.m. PT / 12 Noon EDT - 4:30 p.m. EDTOTN is proud to host another Virtual Developer Day, this time focusing on SOA (click here to check out on-demand version of Rich Enterprise Applications and WebLogic)  Save yourself/company some money and join us online for this hands-on virtual workshop. Through developer-focused product presentations and demonstrations delivered by Oracle product and technology experts, there is no faster or more efficient way to jumpstart your Oracle SOA suite learning.Over the course of the Virtual Developer Day, you will learn how an SOA approach can be implemented, whether starting fresh with new services or reusing existing services. Using Oracle SOA Suite 11g components, you will explore, modify, execute, and monitor an SOA composite application. Topics include SCA, BPEL process execution, adapters, business rules and more.Java and WebLogic experience not required for the presentations or demonstrations but it is a plus for the hands-on lab.Come to this event if you are    •    Exploring ways to deliver services faster    •    Integrating packaged and/or legacy applications    •    Developing service orchestration    •    Planning or starting new development projectsRegister online now for this FREE event.AGENDA - Tuesday July 12, 2011?9:00 a.m. PT – 1:30 p.m. PT / 12 Noon EDT - 4:30 p.m. PT EDT  Time  Title  9:00 AM Keynote  9:15 AM Presentation 1 Service Oriented Architecture (SOA) Overview  9:45 AM Demonstration 1 Mediator and Adapters  10:15 AM Presentation 2 BPEL Service Orchestration and Business Rules  10:45 AM Demonstration 2 BPEL Service Orchestration  11:15 AM Demonstration 3 Oracle Business Rules  11:45 AM Hands-on Lab time  1:30 PM Close Register online now for this FREE event.

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• Juju Zookeeper & Provisioning Agent Not Deployed

  - by Keith Tobin

  I am using juju with the openstack provider, i expected that when i bootstrap that zookeeper and provisioning agent would get deployed on the bootstrap vm in openstack. This dose not seem to be the case. the bootstrap vm gets deployed but it seems that nothing gets deployed to the VM. See logs below, I may be missing something, also how is it possible to log on the bootstrap vm. Could I manual deploy, if so what do I need to do. Juju Bootstrap commend root@cinder01:/home/cinder# juju -v bootstrap 2012-10-12 03:21:20,976 DEBUG Initializing juju bootstrap runtime 2012-10-12 03:21:20,982 WARNING Verification of xxxxS certificates is disabled for this environment. Set 'ssl-hostname-verification' to ensure secure communication. 2012-10-12 03:21:20,982 DEBUG openstack: using auth-mode 'userpass' with xxxx:xxxxxx.10:35357/v2.0/ 2012-10-12 03:21:21,064 DEBUG openstack: authenticated til u'2012-10-13T08:21:13Z' 2012-10-12 03:21:21,064 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors' 2012-10-12 03:21:21,091 DEBUG openstack: 200 '{"flavors": [{"id": "3", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "bookmark"}], "name": "m1.medium"}, {"id": "4", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "bookmark"}], "name": "m1.large"}, {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}], "name": "m1.tiny"}, {"id": "5", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "bookmark"}], "name": "m1.xlarge"}, {"id": "2", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "bookmark"}], "name": "m1.small"}]}' 2012-10-12 03:21:21,091 INFO Bootstrapping environment 'openstack' (origin: ppa type: openstack)... 2012-10-12 03:21:21,091 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:21:21,092 DEBUG openstack: GET 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:21:21,165 DEBUG openstack: 200 '{}\n' 2012-10-12 03:21:21,165 DEBUG Verifying writable storage 2012-10-12 03:21:21,165 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/bootstrap-verify 2012-10-12 03:21:21,166 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/bootstrap-verify' 2012-10-12 03:21:21,251 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:21,251 DEBUG Launching juju bootstrap instance. 2012-10-12 03:21:21,271 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id 2012-10-12 03:21:21,273 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups 2012-10-12 03:21:21,273 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,321 DEBUG openstack: 200 '{"security_groups": [{"rules": [{"from_port": -1, "group": {}, "ip_protocol": "icmp", "to_port": -1, "parent_group_id": 1, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 7}, {"from_port": 22, "group": {}, "ip_protocol": "tcp", "to_port": 22, "parent_group_id": 1, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 38}], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 1, "name": "default", "description": "default"}]}' 2012-10-12 03:21:21,322 DEBUG Creating juju security group juju-openstack 2012-10-12 03:21:21,322 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,401 DEBUG openstack: 200 '{"security_group": {"rules": [], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 48, "name": "juju-openstack", "description": "juju group for openstack"}}' 2012-10-12 03:21:21,401 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,504 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 22, "group": {}, "ip_protocol": "tcp", "to_port": 22, "parent_group_id": 48, "ip_range": {"cidr": "0.0.0.0/0"}, "id": 54}}' 2012-10-12 03:21:21,504 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,647 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 1, "group": {"tenant_id": "d5f52673953f49e595279e89ddde979d", "name": "juju-openstack"}, "ip_protocol": "tcp", "to_port": 65535, "parent_group_id": 48, "ip_range": {}, "id": 55}}' 2012-10-12 03:21:21,647 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-group-rules' 2012-10-12 03:21:21,791 DEBUG openstack: 200 '{"security_group_rule": {"from_port": 1, "group": {"tenant_id": "d5f52673953f49e595279e89ddde979d", "name": "juju-openstack"}, "ip_protocol": "udp", "to_port": 65535, "parent_group_id": 48, "ip_range": {}, "id": 56}}' 2012-10-12 03:21:21,792 DEBUG Creating machine security group juju-openstack-0 2012-10-12 03:21:21,792 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-security-groups' 2012-10-12 03:21:21,871 DEBUG openstack: 200 '{"security_group": {"rules": [], "tenant_id": "d5f52673953f49e595279e89ddde979d", "id": 49, "name": "juju-openstack-0", "description": "juju group for openstack machine 0"}}' 2012-10-12 03:21:21,871 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/detail 2012-10-12 03:21:21,871 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/detail' 2012-10-12 03:21:21,906 DEBUG openstack: 200 '{"flavors": [{"vcpus": 2, "disk": 10, "name": "m1.medium", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/3", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 40, "ram": 4096, "id": "3", "swap": ""}, {"vcpus": 4, "disk": 10, "name": "m1.large", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/4", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 80, "ram": 8192, "id": "4", "swap": ""}, {"vcpus": 1, "disk": 0, "name": "m1.tiny", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 0, "ram": 512, "id": "1", "swap": ""}, {"vcpus": 8, "disk": 10, "name": "m1.xlarge", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/5", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 160, "ram": 16384, "id": "5", "swap": ""}, {"vcpus": 1, "disk": 10, "name": "m1.small", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/2", "rel": "bookmark"}], "rxtx_factor": 1.0, "OS-FLV-EXT-DATA:ephemeral": 20, "ram": 2048, "id": "2", "swap": ""}]}' 2012-10-12 03:21:21,907 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers 2012-10-12 03:21:21,907 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers' 2012-10-12 03:21:22,284 DEBUG openstack: 202 '{"server": {"OS-DCF:diskConfig": "MANUAL", "id": "a598b402-8678-4447-baeb-59255409a023", "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "adminPass": "SuFp48cZzdo4"}}' 2012-10-12 03:21:22,284 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id 2012-10-12 03:21:22,285 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/juju_master_id' 2012-10-12 03:21:22,375 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:27,379 DEBUG Waited for 5 seconds for networking on server u'a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:21:27,380 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023 2012-10-12 03:21:27,380 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:21:27,556 DEBUG openstack: 200 '{"server": {"OS-EXT-STS:task_state": "networking", "addresses": {"private": [{"version": 4, "addr": "10.0.0.8"}]}, "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "image": {"id": "5bf60467-0136-4471-9818-e13ade75a0a1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/images/5bf60467-0136-4471-9818-e13ade75a0a1", "rel": "bookmark"}]}, "OS-EXT-STS:vm_state": "building", "OS-EXT-SRV-ATTR:instance_name": "instance-00000060", "flavor": {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}]}, "id": "a598b402-8678-4447-baeb-59255409a023", "user_id": "01610f73d0fb4922aefff09f2627e50c", "OS-DCF:diskConfig": "MANUAL", "accessIPv4": "", "accessIPv6": "", "progress": 0, "OS-EXT-STS:power_state": 0, "config_drive": "", "status": "BUILD", "updated": "2012-10-12T08:21:23Z", "hostId": "1cdb25708fb8e464d83a69fe4a024dcd5a80baf24a82ec28f9d9f866", "OS-EXT-SRV-ATTR:host": "nova01", "key_name": "", "OS-EXT-SRV-ATTR:hypervisor_hostname": null, "name": "juju openstack instance 0", "created": "2012-10-12T08:21:22Z", "tenant_id": "d5f52673953f49e595279e89ddde979d", "metadata": {}}}' 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 2012-10-12 03:21:27,557 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-floating-ips 2012-10-12 03:21:27,557 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/os-floating-ips' 2012-10-12 03:21:27,815 DEBUG openstack: 200 '{"floating_ips": [{"instance_id": "a0e0df11-91c0-4801-95b3-62d910d729e9", "ip": "xxxx.35", "fixed_ip": "10.0.0.5", "id": 447, "pool": "nova"}, {"instance_id": "b84f1a42-7192-415e-8650-ebb1aa56e97f", "ip": "xxxx.36", "fixed_ip": "10.0.0.6", "id": 448, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.37", "fixed_ip": null, "id": 449, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.38", "fixed_ip": null, "id": 450, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.39", "fixed_ip": null, "id": 451, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.40", "fixed_ip": null, "id": 452, "pool": "nova"}, {"instance_id": null, "ip": "xxxx.41", "fixed_ip": null, "id": 453, "pool": "nova"}]}' 2012-10-12 03:21:27,815 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023/action 2012-10-12 03:21:27,816 DEBUG openstack: POST 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023/action' 2012-10-12 03:21:28,356 DEBUG openstack: 202 '' 2012-10-12 03:21:28,356 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:21:28,357 DEBUG openstack: PUT 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:21:28,446 DEBUG openstack: 201 '201 Created\n\n\n\n ' 2012-10-12 03:21:28,446 INFO 'bootstrap' command finished successfully Juju Status Command root@cinder01:/home/cinder# juju -v status 2012-10-12 03:23:28,314 DEBUG Initializing juju status runtime 2012-10-12 03:23:28,320 WARNING Verification of xxxxS certificates is disabled for this environment. Set 'ssl-hostname-verification' to ensure secure communication. 2012-10-12 03:23:28,320 DEBUG openstack: using auth-mode 'userpass' with xxxx:xxxxxx.10:35357/v2.0/ 2012-10-12 03:23:28,320 INFO Connecting to environment... 2012-10-12 03:23:28,403 DEBUG openstack: authenticated til u'2012-10-13T08:23:20Z' 2012-10-12 03:23:28,403 DEBUG access object-store @ xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state 2012-10-12 03:23:28,403 DEBUG openstack: GET 'xxxx:xx10.49.113.11:8080/v1/AUTH_d5f52673953f49e595279e89ddde979d/juju-hpc-az1-cb/provider-state' 2012-10-12 03:23:35,480 DEBUG openstack: 200 'zookeeper-instances: [a598b402-8678-4447-baeb-59255409a023]\n' 2012-10-12 03:23:35,480 DEBUG access compute @ xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023 2012-10-12 03:23:35,480 DEBUG openstack: GET 'xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023' 2012-10-12 03:23:35,662 DEBUG openstack: 200 '{"server": {"OS-EXT-STS:task_state": null, "addresses": {"private": [{"version": 4, "addr": "10.0.0.8"}, {"version": 4, "addr": "xxxx.37"}]}, "links": [{"href": "xxxx:xxxxxx.15:8774/v1.1/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "self"}, {"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/servers/a598b402-8678-4447-baeb-59255409a023", "rel": "bookmark"}], "image": {"id": "5bf60467-0136-4471-9818-e13ade75a0a1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/images/5bf60467-0136-4471-9818-e13ade75a0a1", "rel": "bookmark"}]}, "OS-EXT-STS:vm_state": "active", "OS-EXT-SRV-ATTR:instance_name": "instance-00000060", "flavor": {"id": "1", "links": [{"href": "xxxx:xxxxxx.15:8774/d5f52673953f49e595279e89ddde979d/flavors/1", "rel": "bookmark"}]}, "id": "a598b402-8678-4447-baeb-59255409a023", "user_id": "01610f73d0fb4922aefff09f2627e50c", "OS-DCF:diskConfig": "MANUAL", "accessIPv4": "", "accessIPv6": "", "progress": 0, "OS-EXT-STS:power_state": 1, "config_drive": "", "status": "ACTIVE", "updated": "2012-10-12T08:21:40Z", "hostId": "1cdb25708fb8e464d83a69fe4a024dcd5a80baf24a82ec28f9d9f866", "OS-EXT-SRV-ATTR:host": "nova01", "key_name": "", "OS-EXT-SRV-ATTR:hypervisor_hostname": null, "name": "juju openstack instance 0", "created": "2012-10-12T08:21:22Z", "tenant_id": "d5f52673953f49e595279e89ddde979d", "metadata": {}}}' 2012-10-12 03:23:35,663 DEBUG Connecting to environment using xxxx.37... 2012-10-12 03:23:35,663 DEBUG Spawning SSH process with remote_user="ubuntu" remote_host="xxxx.37" remote_port="2181" local_port="45859". 2012-10-12 03:23:36,173:4355(0x7fd581973700):ZOO_INFO@log_env@658: Client environment:zookeeper.version=zookeeper C client 3.3.5 2012-10-12 03:23:36,173:4355(0x7fd581973700):ZOO_INFO@log_env@662: Client environment:host.name=cinder01 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@669: Client environment:os.name=Linux 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@670: Client environment:os.arch=3.2.0-23-generic 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@671: Client environment:os.version=#36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@679: Client environment:user.name=cinder 2012-10-12 03:23:36,174:4355(0x7fd581973700):ZOO_INFO@log_env@687: Client environment:user.home=/root 2012-10-12 03:23:36,175:4355(0x7fd581973700):ZOO_INFO@log_env@699: Client environment:user.dir=/home/cinder 2012-10-12 03:23:36,175:4355(0x7fd581973700):ZOO_INFO@zookeeper_init@727: Initiating client connection, host=localhost:45859 sessionTimeout=10000 watcher=0x7fd57f9146b0 sessionId=0 sessionPasswd= context=0x2c1dab0 flags=0 2012-10-12 03:23:36,175:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client 2012-10-12 03:23:39,512:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client 2012-10-12 03:23:42,848:4355(0x7fd577fff700):ZOO_ERROR@handle_socket_error_msg@1579: Socket [127.0.0.1:45859] zk retcode=-4, errno=111(Connection refused): server refused to accept the client ^Croot@cinder01:/home/cinder#

  Read the article

• Evil DRY

  - by StefanSteinegger

  DRY (Don't Repeat Yourself) is a basic software design and coding principle. But there is just no silver bullet. While DRY should increase maintainability by avoiding common design mistakes, it could lead to huge maintenance problems when misunderstood. The root of the problem is most probably that many developers believe that DRY means that any piece of code that is written more then once should be made reusable. But the principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." So the important thing here is "knowledge". Nobody ever said "every piece of code". I try to give some examples of misusing the DRY principle. Code Repetitions by Coincidence There is code that is repeated by pure coincidence. It is not the same code because it is based on the same piece of knowledge, it is just the same by coincidence. It's hard to give an example of such a case. Just think about some lines of code the developer thinks "I already wrote something similar". Then he takes the original code, puts it into a public method, even worse into a base class where none had been there before, puts some weird arguments and some if or switch statements into it to support all special cases and calls this "increasing maintainability based on the DRY principle". The resulting "reusable method" is usually something the developer not even can give a meaningful name, because its contents isn't anything specific, it is just a bunch of code. For the same reason, nobody will really understand this piece of code. Typically this method only makes sense to call after some other method had been called. All the symptoms of really bad design is evident. Fact is, writing this kind of "reusable methods" is worse then copy pasting! Believe me. What will happen when you change this weird piece of code? You can't say what'll happen, because you can't understand what the code is actually doing. So better don't touch it anymore. Maintainability just died. Of course this problem is with any badly designed code. But because the developer tried to make this method as reusable as possible, large parts of the system get dependent on it. Completely independent parts get tightly coupled by this common piece of code. Changing on the single common place will have effects anywhere in the system, a typical symptom of too tight coupling. Without trying to dogmatically (and wrongly) apply the DRY principle, you just had a system with a weak design. Now you get a system which just can't be maintained anymore. So what can you do against it? When making code reusable, always identify the generally reusable parts of it. Find the reason why the code is repeated, find the common "piece of knowledge". If you have to search too far, it's probably not really there. Explain it to a colleague, if you can't explain or the explanation is to complicated, it's probably not worth to reuse. If you identify the piece of knowledge, don't forget to carefully find the place where it should be implemented. Reusing code is never worth giving up a clean design. Methods always need to do something specific. If you can't give it a simple and explanatory name, you did probably something weird. If you can't find the common piece of knowledge, try to make the code simpler. For instance, if you have some complicated string or collection operations within this code, write some general-purpose operations into a helper class. If your code gets simple enough, its not so bad if it can't be reused. If you are not able to find anything simple and reasonable, copy paste it. Put a comment into the code to reference the other copies. You may find a solution later. Requirements Repetitions by Coincidence Let's assume that you need to implement complex tax calculations for many countries. It's possible that some countries have very similar tax rules. These rules are still completely independent from each other, since every country can change it of its own. (Assumed that this similarity is actually by coincidence and not by political membership. There might be basic rules applying to all European countries. etc.) Let's assume that there are similarities between an Asian country and an African country. Moving the common part to a central place will cause problems. What happens if one of the countries changes its rules? Or - more likely - what happens if users of one country complain about an error in the calculation? If there is shared code, it is very risky to change it, even for a bugfix. It is hard to find requirements to be repeated by coincidence. Then there is not much you can do against the repetition of the code. What you really should consider is to make coding of the rules as simple as possible. So this independent knowledge "Tax Rules in Timbuktu" or wherever should be as pure as possible, without much overhead and stuff that does not belong to it. So you can write every independent requirement short and clean. DRYing try-catch and using Blocks This is a technical issue. Blocks like try-catch or using (e.g. in C#) are very hard to DRY. Imagine a complex exception handling, including several catch blocks. When the contents of the try block as well as the contents of the individual catch block are trivial, but the whole structure is repeated on many places in the code, there is almost no reasonable way to DRY it. try { // trivial code here using (Thingy thing = new thingy) { //trivial, but always different line of code } } catch(FooException foo) { // trivial foo handling } catch (BarException bar) { // trivial bar handling } catch { // trivial common handling } finally { // trivial finally block } The key here is that every block is trivial, so there is nothing to just move into a separate method. The only part that differs from case to case is the line of code in the body of the using block (or any other block). The situation is especially interesting if the many occurrences of this structure are completely independent: they appear in classes with no common base class, they don't aggregate each other and so on. Let's assume that this is a common pattern in service methods within the whole system. Examples of Evil DRYing in this situation: Put a if or switch statement into the method to choose the line of code to execute. There are several reasons why this is not a good idea: The close coupling of the formerly independent implementation is the strongest. Also the readability of the code and the use of a parameter to control the logic. Put everything into a method which takes a delegate as argument to call. The caller just passes his "specific line of code" to this method. The code will be very unreadable. The same maintainability problems apply as for any "Code Repetition by Coincidence" situations. Enforce a base class to all the classes where this pattern appears and use the template method pattern. It's the same readability and maintainability problem as above, but additionally complex and tightly coupled because of the base class. I would call this "Inheritance by Coincidence" which will not lead to great software design. What can you do against it: Ideally, the individual line of code is a call to a class or interface, which could be made individual by inheritance. If this would be the case, it wouldn't be a problem at all. I assume that it is no such a trivial case. Consider to refactor the error concept to make error handling easier. The last but not worst option is to keep the replications. Some pattern of code must be maintained in consistency, there is nothing we can do against it. And no reason to make it unreadable. Conclusion The DRY-principle is an important and basic principle every software developer should master. The key is to identify the "pieces of knowledge". There is code which can't be reused easily because of technical reasons. This requires quite a bit flexibility and creativity to make code simple and maintainable. It's not the problem of the principle, it is the problem of blindly applying a principle without understanding the problem it should solve. The result is mostly much worse then ignoring the principle.

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