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cdist manpages update: 4.10.6
2019-02-15 19:48:11 +00:00
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<li class="toctree-l1 current"><a class="current reference internal" href="#">22. Best practice</a><ul>
<li class="toctree-l2"><a class="reference internal" href="#passwordless-connections">22.1. Passwordless connections</a></li>
<li class="toctree-l2"><a class="reference internal" href="#speeding-up-ssh-connections">22.2. Speeding up ssh connections</a></li>
<li class="toctree-l2"><a class="reference internal" href="#speeding-up-shell-execution">22.3. Speeding up shell execution</a></li>
<li class="toctree-l2"><a class="reference internal" href="#multi-master-or-environment-setups">22.4. Multi master or environment setups</a></li>
<li class="toctree-l2"><a class="reference internal" href="#separating-work-by-groups">22.5. Separating work by groups</a></li>
<li class="toctree-l2"><a class="reference internal" href="#maintaining-multiple-configurations">22.6. Maintaining multiple configurations</a></li>
<li class="toctree-l2"><a class="reference internal" href="#multiple-developers-with-different-trust">22.7. Multiple developers with different trust</a></li>
<li class="toctree-l2"><a class="reference internal" href="#templating">22.8. Templating</a></li>
<li class="toctree-l2"><a class="reference internal" href="#testing-a-new-type">22.9. Testing a new type</a></li>
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<div class="section" id="best-practice">
<h1>22. Best practice<a class="headerlink" href="#best-practice" title="Permalink to this headline"></a></h1>
<p>Practices used in real environments</p>
<div class="section" id="passwordless-connections">
<h2>22.1. Passwordless connections<a class="headerlink" href="#passwordless-connections" title="Permalink to this headline"></a></h2>
<p>It is recommended to run cdist with public key authentication.
This requires a private/public key pair and the entry
&quot;PermitRootLogin without-password&quot; in the sshd server.
See sshd_config(5) and ssh-keygen(1).</p>
</div>
<div class="section" id="speeding-up-ssh-connections">
<h2>22.2. Speeding up ssh connections<a class="headerlink" href="#speeding-up-ssh-connections" title="Permalink to this headline"></a></h2>
<p>When connecting to a new host, the initial delay with ssh connections
is pretty big. As cdist makes many connections to each host successive
connections can be sped up by &quot;sharing of multiple sessions over a single
network connection&quot; (quote from ssh_config(5)). This is also called &quot;connection
multiplexing&quot;.</p>
<p>Cdist implements this since v4.0.0 by executing ssh with the appropriate
options (<cite>-o ControlMaster=auto -o ControlPath=/tmp/&lt;tmpdir&gt;/s -o
ControlPersist=2h</cite>).</p>
<p>Note that the sshd_config on the server can configure the maximum number of
parallel multiplexed connections this with <cite>MaxSessions N</cite> (N defaults to 10
for OpenSSH v7.4).</p>
</div>
<div class="section" id="speeding-up-shell-execution">
<h2>22.3. Speeding up shell execution<a class="headerlink" href="#speeding-up-shell-execution" title="Permalink to this headline"></a></h2>
<p>On the source host, ensure that /bin/sh is <em>not</em> bash: bash is quite slow for
script execution. Instead, you could use dash after installing it:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ln</span> <span class="o">-</span><span class="n">sf</span> <span class="o">/</span><span class="nb">bin</span><span class="o">/</span><span class="n">dash</span> <span class="o">/</span><span class="nb">bin</span><span class="o">/</span><span class="n">sh</span>
</pre></div>
</div>
</div>
<div class="section" id="multi-master-or-environment-setups">
<h2>22.4. Multi master or environment setups<a class="headerlink" href="#multi-master-or-environment-setups" title="Permalink to this headline"></a></h2>
<p>If you plan to distribute cdist among servers or use different
environments, you can do so easily with the included version
control git. For instance if you plan to use the typical three
environments production, integration and development, you can
realise this with git branches:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1"># Go to cdist checkout</span>
<span class="n">cd</span> <span class="o">/</span><span class="n">path</span><span class="o">/</span><span class="n">to</span><span class="o">/</span><span class="n">cdist</span>
<span class="c1"># Create branches</span>
<span class="n">git</span> <span class="n">branch</span> <span class="n">development</span>
<span class="n">git</span> <span class="n">branch</span> <span class="n">integration</span>
<span class="n">git</span> <span class="n">branch</span> <span class="n">production</span>
<span class="c1"># Make use of a branch, for instance production</span>
<span class="n">git</span> <span class="n">checkout</span> <span class="n">production</span>
</pre></div>
</div>
<p>Similar if you want to have cdist checked out at multiple machines,
you can clone it multiple times:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">machine</span><span class="o">-</span><span class="n">a</span> <span class="o">%</span> <span class="n">git</span> <span class="n">clone</span> <span class="n">git</span><span class="p">:</span><span class="o">//</span><span class="n">your</span><span class="o">-</span><span class="n">git</span><span class="o">-</span><span class="n">server</span><span class="o">/</span><span class="n">cdist</span>
<span class="n">machine</span><span class="o">-</span><span class="n">b</span> <span class="o">%</span> <span class="n">git</span> <span class="n">clone</span> <span class="n">git</span><span class="p">:</span><span class="o">//</span><span class="n">your</span><span class="o">-</span><span class="n">git</span><span class="o">-</span><span class="n">server</span><span class="o">/</span><span class="n">cdist</span>
</pre></div>
</div>
</div>
<div class="section" id="separating-work-by-groups">
<h2>22.5. Separating work by groups<a class="headerlink" href="#separating-work-by-groups" title="Permalink to this headline"></a></h2>
<p>If you are working with different groups on one cdist-configuration,
you can delegate to other manifests and have the groups edit only
their manifests. You can use the following snippet in
<strong>conf/manifests/init</strong>:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1"># Include other groups</span>
<span class="n">sh</span> <span class="o">-</span><span class="n">e</span> <span class="s2">&quot;$__manifest/systems&quot;</span>
<span class="n">sh</span> <span class="o">-</span><span class="n">e</span> <span class="s2">&quot;$__manifest/cbrg&quot;</span>
</pre></div>
</div>
</div>
<div class="section" id="maintaining-multiple-configurations">
<h2>22.6. Maintaining multiple configurations<a class="headerlink" href="#maintaining-multiple-configurations" title="Permalink to this headline"></a></h2>
<p>When you need to manage multiple sites with cdist, like company_a, company_b
and private for instance, you can easily use git for this purpose.
Including a possible common base that is reused across the different sites:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1"># create branches</span>
<span class="n">git</span> <span class="n">branch</span> <span class="n">company_a</span> <span class="n">company_b</span> <span class="n">common</span> <span class="n">private</span>
<span class="c1"># make stuff for company a</span>
<span class="n">git</span> <span class="n">checkout</span> <span class="n">company_a</span>
<span class="c1"># work, commit, etc.</span>
<span class="c1"># make stuff for company b</span>
<span class="n">git</span> <span class="n">checkout</span> <span class="n">company_b</span>
<span class="c1"># work, commit, etc.</span>
<span class="c1"># make stuff relevant for all sites</span>
<span class="n">git</span> <span class="n">checkout</span> <span class="n">common</span>
<span class="c1"># work, commit, etc.</span>
<span class="c1"># change to private and include latest common stuff</span>
<span class="n">git</span> <span class="n">checkout</span> <span class="n">private</span>
<span class="n">git</span> <span class="n">merge</span> <span class="n">common</span>
</pre></div>
</div>
<p>The following <strong>.git/config</strong> is taken from a real world scenario:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1"># Track upstream, merge from time to time</span>
<span class="p">[</span><span class="n">remote</span> <span class="s2">&quot;upstream&quot;</span><span class="p">]</span>
<span class="n">url</span> <span class="o">=</span> <span class="n">git</span><span class="p">:</span><span class="o">//</span><span class="n">git</span><span class="o">.</span><span class="n">schottelius</span><span class="o">.</span><span class="n">org</span><span class="o">/</span><span class="n">cdist</span>
<span class="n">fetch</span> <span class="o">=</span> <span class="o">+</span><span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/*</span><span class="p">:</span><span class="n">refs</span><span class="o">/</span><span class="n">remotes</span><span class="o">/</span><span class="n">upstream</span><span class="o">/*</span>
<span class="c1"># Same as upstream, but works when being offline</span>
<span class="p">[</span><span class="n">remote</span> <span class="s2">&quot;local&quot;</span><span class="p">]</span>
<span class="n">fetch</span> <span class="o">=</span> <span class="o">+</span><span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/*</span><span class="p">:</span><span class="n">refs</span><span class="o">/</span><span class="n">remotes</span><span class="o">/</span><span class="n">local</span><span class="o">/*</span>
<span class="n">url</span> <span class="o">=</span> <span class="o">/</span><span class="n">home</span><span class="o">/</span><span class="n">users</span><span class="o">/</span><span class="n">nico</span><span class="o">/</span><span class="n">p</span><span class="o">/</span><span class="n">cdist</span>
<span class="c1"># Remote containing various ETH internal branches</span>
<span class="p">[</span><span class="n">remote</span> <span class="s2">&quot;eth&quot;</span><span class="p">]</span>
<span class="n">url</span> <span class="o">=</span> <span class="n">sans</span><span class="o">.</span><span class="n">ethz</span><span class="o">.</span><span class="n">ch</span><span class="p">:</span><span class="o">/</span><span class="n">home</span><span class="o">/</span><span class="n">services</span><span class="o">/</span><span class="n">sans</span><span class="o">/</span><span class="n">git</span><span class="o">/</span><span class="n">cdist</span><span class="o">-</span><span class="n">eth</span>
<span class="n">fetch</span> <span class="o">=</span> <span class="o">+</span><span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/*</span><span class="p">:</span><span class="n">refs</span><span class="o">/</span><span class="n">remotes</span><span class="o">/</span><span class="n">eth</span><span class="o">/*</span>
<span class="c1"># Public remote that contains my private changes to cdist upstream</span>
<span class="p">[</span><span class="n">remote</span> <span class="s2">&quot;nico&quot;</span><span class="p">]</span>
<span class="n">url</span> <span class="o">=</span> <span class="n">git</span><span class="o">.</span><span class="n">schottelius</span><span class="o">.</span><span class="n">org</span><span class="p">:</span><span class="o">/</span><span class="n">home</span><span class="o">/</span><span class="n">services</span><span class="o">/</span><span class="n">git</span><span class="o">/</span><span class="n">cdist</span><span class="o">-</span><span class="n">nico</span>
<span class="n">fetch</span> <span class="o">=</span> <span class="o">+</span><span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/*</span><span class="p">:</span><span class="n">refs</span><span class="o">/</span><span class="n">remotes</span><span class="o">/</span><span class="n">nico</span><span class="o">/*</span>
<span class="c1"># The &quot;nico&quot; branch will be synced with the remote nico, branch master</span>
<span class="p">[</span><span class="n">branch</span> <span class="s2">&quot;nico&quot;</span><span class="p">]</span>
<span class="n">remote</span> <span class="o">=</span> <span class="n">nico</span>
<span class="n">merge</span> <span class="o">=</span> <span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/</span><span class="n">master</span>
<span class="c1"># ETH stable contains rock solid configurations used in various places</span>
<span class="p">[</span><span class="n">branch</span> <span class="s2">&quot;eth-stable&quot;</span><span class="p">]</span>
<span class="n">remote</span> <span class="o">=</span> <span class="n">eth</span>
<span class="n">merge</span> <span class="o">=</span> <span class="n">refs</span><span class="o">/</span><span class="n">heads</span><span class="o">/</span><span class="n">stable</span>
</pre></div>
</div>
<p>Have a look at git-remote(1) to adjust the remote configuration, which allows</p>
</div>
<div class="section" id="multiple-developers-with-different-trust">
<h2>22.7. Multiple developers with different trust<a class="headerlink" href="#multiple-developers-with-different-trust" title="Permalink to this headline"></a></h2>
<p>If you are working in an environment that requires different people to
work on the same configuration, but having different privileges, you can
implement this scenario with a gateway host and sudo:</p>
<ul>
<li><p class="first">Create a dedicated user (for instance <strong>cdist</strong>)</p>
</li>
<li><p class="first">Setup the ssh-pubkey for this user that has the right to configure all hosts</p>
</li>
<li><p class="first">Create a wrapper to update the cdist configuration in ~cdist/cdist</p>
</li>
<li><p class="first">Allow every developer to execute this script via sudo as the user cdist</p>
</li>
<li><p class="first">Allow run of cdist as user cdist on specific hosts on a per user/group basis.</p>
<blockquote>
<div><ul class="simple">
<li>f.i. nico ALL=(ALL) NOPASSWD: /home/cdist/bin/cdist config hostabc</li>
</ul>
</div></blockquote>
</li>
</ul>
<p>For more details consult sudoers(5)</p>
</div>
<div class="section" id="templating">
<h2>22.8. Templating<a class="headerlink" href="#templating" title="Permalink to this headline"></a></h2>
<ul class="simple">
<li>create directory files/ in your type (convention)</li>
<li>create the template as an executable file like files/basic.conf.sh, it will output text using shell variables for the values</li>
</ul>
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span><span class="ch">#!/bin/sh</span>
<span class="c1"># in the template, use cat &lt;&lt; eof (here document) to output the text</span>
<span class="c1"># and use standard shell variables in the template</span>
<span class="c1"># output everything in the template script to stdout</span>
cat <span class="s">&lt;&lt; EOF</span>
<span class="s">server {</span>
<span class="s"> listen 80;</span>
<span class="s"> server_name $SERVERNAME;</span>
<span class="s"> root $ROOT;</span>
<span class="s"> access_log /var/log/nginx/$SERVERNAME_access.log</span>
<span class="s"> error_log /var/log/nginx/$SERVERNAME_error.log</span>
<span class="s">}</span>
<span class="s">EOF</span>
</pre></div>
</div>
<ul class="simple">
<li>in the manifest, export the relevant variables and add the following lines to your manifest:</li>
</ul>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">#</span> <span class="nb">export</span> variables needed <span class="k">for</span> the template
<span class="go"> export SERVERNAME=&#39;test&quot;</span>
<span class="go"> export ROOT=&#39;/var/www/test&#39;</span>
<span class="gp">#</span> render the template
<span class="go"> mkdir -p &quot;$__object/files&quot;</span>
<span class="go"> &quot;$__type/files/basic.conf.sh&quot; &gt; &quot;$__object/files/basic.conf&quot;</span>
<span class="gp">#</span> send the rendered template
<span class="go"> __file /etc/nginx/sites-available/test.conf \</span>
<span class="go"> --state present</span>
<span class="go"> --source &quot;$__object/files/basic.conf&quot;</span>
</pre></div>
</div>
</div>
<div class="section" id="testing-a-new-type">
<h2>22.9. Testing a new type<a class="headerlink" href="#testing-a-new-type" title="Permalink to this headline"></a></h2>
<p>If you want to test a new type on a node, you can tell cdist to only use an
object of this type: Use the '--initial-manifest' parameter
with - (stdin) as argument and feed object into stdin
of cdist:</p>
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span><span class="c1"># Singleton type without parameter</span>
<span class="nb">echo</span> __ungleich_munin_server <span class="p">|</span> cdist --initial-manifest - munin.panter.ch
<span class="c1"># Singleton type with parameter</span>
<span class="nb">echo</span> __ungleich_munin_node --allow <span class="m">1</span>.2.3.4 <span class="p">|</span> <span class="se">\</span>
cdist --initial-manifest - rails-19.panter.ch
<span class="c1"># Normal type</span>
<span class="nb">echo</span> __file /tmp/stdintest --mode <span class="m">0644</span> <span class="p">|</span> <span class="se">\</span>
cdist --initial-manifest - cdist-dev-01.ungleich.ch
</pre></div>
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<div class="section" id="other-content-in-cdist-repository">
<h2>22.10. Other content in cdist repository<a class="headerlink" href="#other-content-in-cdist-repository" title="Permalink to this headline"></a></h2>
<p>Usually the cdist repository contains all configuration
items. Sometimes you may have additional resources that
you would like to store in your central configuration
repository (like password files from KeepassX,
Libreoffice diagrams, etc.).</p>
<p>It is recommended to use a subfolder named &quot;non-cdist&quot;
in the repository for such content: It allows you to
easily distinguish what is used by cdist and what is not
and also to store all important files in one
repository.</p>
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