www.nico.schottelius.org/software/cdist/man/4.3.0/cdist-messaging.html
2016-08-19 21:29:34 +02:00

307 lines
No EOL
12 KiB
HTML

<!DOCTYPE html>
<!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]-->
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>15. Messaging &mdash; cdist 4.3.0 documentation</title>
<link rel="stylesheet" href="_static/css/theme.css" type="text/css" />
<link rel="top" title="cdist 4.3.0 documentation" href="index.html"/>
<link rel="next" title="16. Parallelization" href="cdist-parallelization.html"/>
<link rel="prev" title="14. Explorer" href="cdist-explorer.html"/>
<script src="_static/js/modernizr.min.js"></script>
</head>
<body class="wy-body-for-nav" role="document">
<div class="wy-grid-for-nav">
<nav data-toggle="wy-nav-shift" class="wy-nav-side">
<div class="wy-side-scroll">
<div class="wy-side-nav-search">
<a href="index.html" class="icon icon-home"> cdist
</a>
<div class="version">
4.3.0
</div>
<div role="search">
<form id="rtd-search-form" class="wy-form" action="search.html" method="get">
<input type="text" name="q" placeholder="Search docs" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
<div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="cdist-intro.html">1. cdist - usable configuration management</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-why.html">2. Why should I use cdist?</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-os.html">3. Supported Operating Systems</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-install.html">4. How to install cdist</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-update.html">5. How to update cdist</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-support.html">6. Support</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-features.html">7. Features</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-quickstart.html">8. Quickstart</a></li>
<li class="toctree-l1"><a class="reference internal" href="man1/cdist.html">9. cdist(1)</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-bootstrap.html">10. Bootstrap</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-manifest.html">11. Manifest</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-type.html">12. cdist type</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-types.html">13. cdist types</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-explorer.html">14. Explorer</a></li>
<li class="toctree-l1 current"><a class="current reference internal" href="#">15. Messaging</a><ul>
<li class="toctree-l2"><a class="reference internal" href="#description">15.1. Description</a></li>
<li class="toctree-l2"><a class="reference internal" href="#availability">15.2. Availability</a></li>
<li class="toctree-l2"><a class="reference internal" href="#examples">15.3. Examples</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="cdist-parallelization.html">16. Parallelization</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-reference.html">17. Reference</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-best-practice.html">18. Best practice</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-stages.html">19. Execution stages</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-remote-exec-copy.html">20. Remote exec and copy commands</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-hacker.html">21. Hacking</a></li>
<li class="toctree-l1"><a class="reference internal" href="cdist-troubleshooting.html">22. Troubleshooting</a></li>
</ul>
</div>
</div>
</nav>
<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">
<nav class="wy-nav-top" role="navigation" aria-label="top navigation">
<i data-toggle="wy-nav-top" class="fa fa-bars"></i>
<a href="index.html">cdist</a>
</nav>
<div class="wy-nav-content">
<div class="rst-content">
<div role="navigation" aria-label="breadcrumbs navigation">
<ul class="wy-breadcrumbs">
<li><a href="index.html">Docs</a> &raquo;</li>
<li>15. Messaging</li>
<li class="wy-breadcrumbs-aside">
<a href="_sources/cdist-messaging.txt" rel="nofollow"> View page source</a>
</li>
</ul>
<hr/>
</div>
<div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
<div itemprop="articleBody">
<div class="section" id="messaging">
<h1>15. Messaging<a class="headerlink" href="#messaging" title="Permalink to this headline"></a></h1>
<div class="section" id="description">
<h2>15.1. Description<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
<p>cdist has a simple but powerful way of allowing communication between
the initial manifest and types as well as types and types.</p>
<p>Whenever execution is passed from cdist to one of the
scripts described below, cdist generate 2 new temporary files
and exports the environment variables <strong>__messages_in</strong> and
<strong>__messages_out</strong> to point to them.</p>
<p>Before handing over the control, the content of the global message
file is copied into the file referenced by <strong>$__messages_in</strong>.</p>
<p>After cdist gained control back, the content of the file referenced
by <strong>$__messages_out</strong> is appended to the global message file.</p>
<p>This way overwriting any of the two files by accident does not
interfere with other types.</p>
<p>The order of execution is not defined unless you create dependencies
between the different objects (see <a class="reference external" href="cdist-manifest.html">cdist manifest</a>) and thus you
can only react reliably on messages by objects that you depend on.</p>
</div>
<div class="section" id="availability">
<h2>15.2. Availability<a class="headerlink" href="#availability" title="Permalink to this headline"></a></h2>
<p>Messaging is possible between all <strong>local</strong> scripts:</p>
<ul class="simple">
<li>initial manifest</li>
<li>type/manifest</li>
<li>type/gencode-local</li>
<li>type/gencode-remote</li>
</ul>
</div>
<div class="section" id="examples">
<h2>15.3. Examples<a class="headerlink" href="#examples" title="Permalink to this headline"></a></h2>
<p>When you want to emit a message use:</p>
<div class="highlight-sh"><div class="highlight"><pre><span></span><span class="nb">echo</span> <span class="s2">&quot;something&quot;</span> &gt;&gt; <span class="s2">&quot;</span><span class="nv">$__messages_out</span><span class="s2">&quot;</span>
</pre></div>
</div>
<p>When you want to react on a message use:</p>
<div class="highlight-sh"><div class="highlight"><pre><span></span><span class="k">if</span> grep -q <span class="s2">&quot;^__your_type/object/id:something&quot;</span> <span class="s2">&quot;</span><span class="nv">$__messages_in</span><span class="s2">&quot;</span><span class="p">;</span> <span class="k">then</span>
<span class="nb">echo</span> <span class="s2">&quot;I do something else&quot;</span>
<span class="k">fi</span>
</pre></div>
</div>
<p>Some real life examples:</p>
<div class="highlight-sh"><div class="highlight"><pre><span></span><span class="c1"># Reacting on changes from block for keepalive</span>
<span class="k">if</span> grep -q <span class="s2">&quot;^__block/keepalive-vrrp&quot;</span> <span class="s2">&quot;</span><span class="nv">$__messages_in</span><span class="s2">&quot;</span><span class="p">;</span> <span class="k">then</span>
<span class="nb">echo</span> /etc/init.d/keepalived restart
<span class="k">fi</span>
<span class="c1"># Reacting on changes of configuration files</span>
<span class="k">if</span> grep -q <span class="s2">&quot;^__file/etc/one&quot;</span> <span class="nv">$__messages_in</span><span class="p">;</span> <span class="k">then</span>
<span class="nb">echo</span> <span class="s1">&#39;for init in /etc/init.d/opennebula*; do $init restart; done&#39;</span>
<span class="k">fi</span>
</pre></div>
</div>
<p>Restart sshd on changes</p>
<div class="highlight-sh"><div class="highlight"><pre><span></span><span class="nv">os</span><span class="o">=</span><span class="s2">&quot;</span><span class="k">$(</span>cat <span class="s2">&quot;</span><span class="nv">$__global</span><span class="s2">/explorer/os&quot;</span><span class="k">)</span><span class="s2">&quot;</span>
<span class="k">case</span> <span class="s2">&quot;</span><span class="nv">$os</span><span class="s2">&quot;</span> in
centos<span class="p">|</span>redhat<span class="p">|</span>suse<span class="o">)</span>
<span class="nv">restart</span><span class="o">=</span><span class="s2">&quot;/etc/init.d/sshd restart&quot;</span>
<span class="p">;;</span>
debian<span class="p">|</span>ubuntu<span class="o">)</span>
<span class="nv">restart</span><span class="o">=</span><span class="s2">&quot;/etc/init.d/ssh restart&quot;</span>
<span class="p">;;</span>
*<span class="o">)</span>
cat <span class="s">&lt;&lt; eof &gt;&amp;2</span>
<span class="s">Unsupported os $os.</span>
<span class="s">If you would like to have this type running on $os,</span>
<span class="s">you can either develop the changes and send a pull</span>
<span class="s">request or ask for a quote at www.ungleich.ch</span>
<span class="s">eof</span>
<span class="nb">exit</span> 1
<span class="p">;;</span>
<span class="k">esac</span>
<span class="k">if</span> grep -q <span class="s2">&quot;^__key_value/PermitRootLogin&quot;</span> <span class="s2">&quot;</span><span class="nv">$__messages_in</span><span class="s2">&quot;</span><span class="p">;</span> <span class="k">then</span>
<span class="nb">echo</span> <span class="nv">$restart</span>
<span class="k">fi</span>
</pre></div>
</div>
</div>
</div>
</div>
</div>
<footer>
<div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
<a href="cdist-parallelization.html" class="btn btn-neutral float-right" title="16. Parallelization" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
<a href="cdist-explorer.html" class="btn btn-neutral" title="14. Explorer" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
</div>
<hr/>
<div role="contentinfo">
<p>
&copy; Copyright .
</p>
</div>
Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>.
</footer>
</div>
</div>
</section>
</div>
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT:'./',
VERSION:'4.3.0',
COLLAPSE_INDEX:false,
FILE_SUFFIX:'.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="_static/jquery.js"></script>
<script type="text/javascript" src="_static/underscore.js"></script>
<script type="text/javascript" src="_static/doctools.js"></script>
<script type="text/javascript" src="_static/js/theme.js"></script>
<script type="text/javascript">
jQuery(function () {
SphinxRtdTheme.StickyNav.enable();
});
</script>
</body>
</html>