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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>cdist-best-practice(7)</title><link rel="stylesheet" type="text/css" href="docbook-xsl.css" /><meta name="generator" content="DocBook XSL Stylesheets V1.78.0" /></head><body><div xml:lang="en" class="article" lang="en"><div class="titlepage"><div><div><h2 class="title"><a id="idp198672"></a>cdist-best-practice(7)</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Nico</span> <span class="surname">Schottelius</span></h3><code class="email"><<a class="email" href="mailto:nico-cdist--@--schottelius.org">nico-cdist--@--schottelius.org</a>></code></div></div></div><hr /></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#_name">1. NAME</a></span></dt><dt><span class="section"><a href="#_passwordless_connections">2. PASSWORDLESS CONNECTIONS</a></span></dt><dt><span class="section"><a href="#_speeding_up_ssh_connections">3. SPEEDING UP SSH CONNECTIONS</a></span></dt><dt><span class="section"><a href="#_speeding_up_shell_execution">4. SPEEDING UP SHELL EXECUTION</a></span></dt><dt><span class="section"><a href="#_multi_master_or_environment_setups">5. MULTI MASTER OR ENVIRONMENT SETUPS</a></span></dt><dt><span class="section"><a href="#_seperating_work_by_groups">6. SEPERATING WORK BY GROUPS</a></span></dt><dt><span class="section"><a href="#_maintaining_multiple_configurations">7. MAINTAINING MULTIPLE CONFIGURATIONS</a></span></dt><dt><span class="section"><a href="#_multiple_developers_with_different_trust">8. MULTIPLE DEVELOPERS WITH DIFFERENT TRUST</a></span></dt><dt><span class="section"><a href="#_templating">9. TEMPLATING</a></span></dt><dt><span class="section"><a href="#_see_also">10. SEE ALSO</a></span></dt><dt><span class="section"><a href="#_copying">11. COPYING</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_name"></a>1. NAME</h2></div></div></div><p>cdist-best-practice - Practices used in real environments</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_passwordless_connections"></a>2. PASSWORDLESS CONNECTIONS</h2></div></div></div><p>It is recommended to run cdist with public key authentication.
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This requires a private/public key pair and the entry
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"PermitRootLogin without-password" in the sshd server.
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See sshd_config(5) and ssh-keygen(1).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_speeding_up_ssh_connections"></a>3. SPEEDING UP SSH CONNECTIONS</h2></div></div></div><p>When connecting to a new host, the initial delay with ssh connections
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is pretty big. You can work around this by
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"sharing of multiple sessions over a single network connection"
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(quote from ssh_config(5)). The following code is suitable for
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inclusion into your ~/.ssh/config:</p><pre class="screen">Host *
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ControlPath ~/.ssh/master-%l-%r@%h:%p
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ControlMaster auto
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ControlPersist 10</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_speeding_up_shell_execution"></a>4. SPEEDING UP SHELL EXECUTION</h2></div></div></div><p>On the source host, ensure that /bin/sh is <span class="strong"><strong>not</strong></span> bash: bash is quite slow for
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script execution. Instead, you could use dash after installing it:</p><pre class="screen">ln -sf /bin/dash /bin/sh</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_multi_master_or_environment_setups"></a>5. MULTI MASTER OR ENVIRONMENT SETUPS</h2></div></div></div><p>If you plan to distribute cdist among servers or use different
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environments, you can do so easily with the included version
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control git. For instance if you plan to use the typical three
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environments production, integration and development, you can
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realise this with git branches:</p><pre class="screen"># Go to cdist checkout
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cd /path/to/cdist
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# Create branches
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git branch development
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git branch integration
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git branch production
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# Make use of a branch, for instance production
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git checkout production</pre><p>Similar if you want to have cdist checked out at multiple machines,
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you can clone it multiple times:</p><pre class="screen">machine-a % git clone git://your-git-server/cdist
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machine-b % git clone git://your-git-server/cdist</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_seperating_work_by_groups"></a>6. SEPERATING WORK BY GROUPS</h2></div></div></div><p>If you are working with different groups on one cdist-configuration,
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you can delegate to other manifests and have the groups edit only
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their manifests. You can use the following snippet in
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<span class="strong"><strong>conf/manifests/init</strong></span>:</p><pre class="screen"># Include other groups
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sh -e "$__manifest/systems"
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sh -e "$__manifest/cbrg"</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_maintaining_multiple_configurations"></a>7. MAINTAINING MULTIPLE CONFIGURATIONS</h2></div></div></div><p>When you need to manage multiple sites with cdist, like company_a, company_b
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and private for instance, you can easily use git for this purpose.
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Including a possible common base that is reused accross the different sites:</p><pre class="screen"># create branches
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git branch company_a company_b common private
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# make stuff for company a
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git checkout company_a
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# work, commit, etc.
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# make stuff for company b
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git checkout company_b
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# work, commit, etc.
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# make stuff relevant for all sites
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git checkout common
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# work, commit, etc.
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# change to private and include latest common stuff
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git checkout private
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git merge common</pre><p>The following <span class="strong"><strong>.git/config</strong></span> is taken from a a real world scenario:</p><pre class="screen"># Track upstream, merge from time to time
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[remote "upstream"]
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url = git://git.schottelius.org/cdist
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fetch = +refs/heads/*:refs/remotes/upstream/*
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# Same as upstream, but works when being offline
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[remote "local"]
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fetch = +refs/heads/*:refs/remotes/local/*
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url = /home/users/nico/p/cdist
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# Remote containing various ETH internal branches
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[remote "eth"]
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url = sans.ethz.ch:/home/services/sans/git/cdist-eth
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fetch = +refs/heads/*:refs/remotes/eth/*
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# Public remote that contains my private changes to cdist upstream
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[remote "nico"]
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url = git.schottelius.org:/home/services/git/cdist-nico
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fetch = +refs/heads/*:refs/remotes/nico/*
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# The "nico" branch will be synced with the remote nico, branch master
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[branch "nico"]
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remote = nico
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merge = refs/heads/master
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# ETH stable contains rock solid configurations used in various places
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[branch "eth-stable"]
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remote = eth
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merge = refs/heads/stable</pre><p>Have a look at git-remote(1) to adjust the remote configuration, which allows</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_multiple_developers_with_different_trust"></a>8. MULTIPLE DEVELOPERS WITH DIFFERENT TRUST</h2></div></div></div><p>If you are working in an environment that requires different people to
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work on the same configuration, but having different privileges, you can
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implement this scenario with a gateway host and sudo:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
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Create a dedicated user (for instance <span class="strong"><strong>cdist</strong></span>)
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</li><li class="listitem">
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Setup the ssh-pubkey for this user that has the right to configure all hosts
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</li><li class="listitem">
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Create a wrapper to update the cdist configuration in ~cdist/cdist
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</li><li class="listitem">
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Allow every developer to execute this script via sudo as the user cdist
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</li><li class="listitem">
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Allow run of cdist as user cdist on specific hosts on a per user/group base
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</li><li class="listitem">
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f.i. nico ALL=(ALL) NOPASSWD: /home/cdist/bin/cdist config hostabc
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</li></ul></div><p>For more details consult sudoers(5)</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_templating"></a>9. TEMPLATING</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
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create directory templates/ in your type (convention)
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</li><li class="listitem">
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create the template as an executable file like templates/basic.conf.sh, it will output text using shell variables for the values
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</li></ul></div><pre class="screen">#!/bin/sh
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# in the template, use cat << eof (here document) to output the text
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# and use standard shell variables in the template
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# output everything in the template script to stdout
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cat << EOF
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server {
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listen 80;
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server_name $SERVERNAME;
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root $ROOT;
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access_log /var/log/nginx/$SERVERNAME_access.log
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error_log /var/log/nginx/$SERVERNAME_error.log
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}
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EOF</pre><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
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in the manifest, export the relevant variables and add the following lines in your manifest:
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</li></ul></div><pre class="screen"># export variables needed for the template
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export SERVERNAME='test"
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export ROOT='/var/www/test'
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# render the template
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mkdir -p "$__object/files"
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"$__type/templates/basic.conf.sh" > "$__object/files/basic.conf"
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# send the rendered template
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__file /etc/nginx/sites-available/test.conf --state present --source "$__object/files/basic.conf"</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_see_also"></a>10. SEE ALSO</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
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cdist(1)
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</li><li class="listitem">
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cdist-tutorial(7)
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</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="_copying"></a>11. COPYING</h2></div></div></div><p>Copyright (C) 2011-2012 Nico Schottelius. Free use of this software is
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granted under the terms of the GNU General Public License version 3 (GPLv3).</p></div></div></body></html>
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