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| author | Owen Jacobson <owen.jacobson@grimoire.ca> | 2015-12-09 20:40:42 -0500 |
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| committer | Owen Jacobson <owen.jacobson@grimoire.ca> | 2015-12-09 20:40:42 -0500 |
| commit | f82d259e7bda843fb63ac1a0f6ff1d6bfb187099 (patch) | |
| tree | 502ebf27ea72cf8c6025b880bfdb35db00ce8b92 /.html/devops/glassfish-and-upstart.html | |
| parent | 75a219a061b60bb32948b8a2b71c8ccf1dc19a62 (diff) | |
Remove HTML from the project. (We're no longer using Dokku.)
Diffstat (limited to '.html/devops/glassfish-and-upstart.html')
| -rw-r--r-- | .html/devops/glassfish-and-upstart.html | 231 |
1 files changed, 0 insertions, 231 deletions
diff --git a/.html/devops/glassfish-and-upstart.html b/.html/devops/glassfish-and-upstart.html deleted file mode 100644 index 0d03620..0000000 --- a/.html/devops/glassfish-and-upstart.html +++ /dev/null @@ -1,231 +0,0 @@ -<!DOCTYPE html> -<html> -<head> - <title> - The Codex » - Glassfish and Upstart - </title> - - <link - rel='stylesheet' - type='text/css' - href='http://fonts.googleapis.com/css?family=Buenard:400,700&subset=latin,latin-ext'> - <link - rel="stylesheet" - type="text/css" - href="../media/css/reset.css"> - <link - rel="stylesheet" - type="text/css" - href="../media/css/grimoire.css"> -</head> -<body> - -<div id="shell"> - - <ol id="breadcrumbs"> - - <li class="crumb-0 not-last"> - - <a href="../">index</a> - - </li> - - <li class="crumb-1 not-last"> - - <a href="./">devops</a> - - </li> - - <li class="crumb-2 last"> - - glassfish-and-upstart - - </li> - - </ol> - - - - <div id="article"> - <h1 id="glassfish-and-upstart">Glassfish and Upstart</h1> -<p><strong>Warning</strong>: the article you're about to read is largely empirical. Take -everything in it in a grain of salt, and <em>verify it yourself</em> before putting -it into production. You have been warned.</p> -<p>The following observations apply to Glassfish 3.1.2.2. Other versions probably -act similarly, but check the docs.</p> -<h2 id="asadmin-create-service"><code>asadmin create-service</code></h2> -<p>Glassfish is capable of emitting SysV init scripts for the DAS, or for any -instance. These init scripts wrap <code>asadmin start-domain</code> and <code>asadmin -start-local-instance</code>. However, the scripts it emits are (justifiably) -minimalist, and it makes some very strong assumptions about the layout of your -system's rc.d trees and about your system's choice of runlevels. The minimal -init scripts avoid any integration with platform “enhancements” (such as -Redhat's <code>/var/lock/subsys</code> mechanism and <code>condrestart</code> convention, or -Debian's <code>start-stop-daemon</code> helpers) in the name of portability, and the -assumptions it makes about runlevels and init layout are becoming -incrementally more fragile as more distributions switch to alternate init -systems with SysV compatiblity layers.</p> -<h2 id="fork-and-expect">Fork and <code>expect</code></h2> -<p>Upstart's process tracking mechanism relies on services following one of three -forking models, so that it can accurately track which children of PID 1 are -associated with which services:</p> -<ul> -<li> -<p>No <code>expect</code> stanza: The service's “main” process is expected not to fork at - all, and to remain running. The process started by upstart is the “main” - process.</p> -</li> -<li> -<p><code>expect fork</code>: The service is expected to call <code>fork()</code> or <code>clone()</code> once. - The process started by upstart itself is not the “main” process, but its - first child process is.</p> -</li> -<li> -<p><code>expect daemon</code>: The service is expected to call <code>fork()</code> or <code>clone()</code> - twice. The first grandchild process of the one started by upstart itself is - the “main” process. This corresponds to classical Unix daemons, which fork - twice to properly dissociate themselves from the launching shell.</p> -</li> -</ul> -<p>Surprisingly, <code>asadmin</code>-launched Glassfish matches <em>none</em> of these models, and -using <code>asadmin start-domain</code> to launch Glassfish from Upstart is not, as far -as I can tell, possible. It's tricky to debug why, since JVM thread creation -floods <code>strace</code> with chaff, but I suspect that either <code>asadmin</code> or Glassfish -itself is forking too many times.</p> -<p>From <a href="https://java.net/projects/glassfish/lists/dev/archive/2012-02/message/9">this mailing list -thread</a>, -though, it appears to be safe to launch Glassfish directly, using <code>java -jar -GLASSFISH_ROOT/modules/glassfish.jar -domain DOMAIN</code>. This fits nicely into -Upstart's non-forking expect mode, but you lose the ability to pass VM -configuration settings to Glassfish during startup. Any memory settings or -Java environment properties you want to pass to Glassfish have to be passed to -the <code>java</code> command manually.</p> -<p>You also lose <code>asadmin</code>'s treatment of Glassfish's working directory. Since -Upstart can configure the working directory, this isn't a big deal.</p> -<h2 id="sigterm-versus-asadmin-stop-domain"><code>SIGTERM</code> versus <code>asadmin stop-domain</code></h2> -<p>Upstart always stops services by sending them a signal. While you can dictate -which signal it uses, you cannot replace signals with another mechanims. -Glassfish shuts down abruptly when it recieves <code>SIGTERM</code> or <code>SIGINT</code>, leaving -some ugly noise in the logs and potentially aborting any transactions and -requests in flight. The Glassfish developers believe this is harmless and that -the server's operation is correct, and that's probably true, but I've not -tested its effect on outward-facing requests or on in-flight operations far -enough to be comfortable with it.</p> -<p>I chose to run a “clean”(er) shutdown using <code>asadmin stop-domain</code>. This fits -nicely in Upstart's <code>pre-stop</code> step, <em>provided you do not use Upstart's -<code>respawn</code> feature</em>. Upstart will correctly notice that Glassfish has already -stopped after <code>pre-stop</code> finishes, but when <code>respawn</code> is enabled Upstart will -treat this as an unexpected termination, switch goals from <code>stop</code> to -<code>respawn</code>, and restart Glassfish.</p> -<p>(The Upstart documentation claims that <code>respawn</code> does not apply if the tracked -process exits during <code>pre-stop</code>. This may be true in newer versions of -Upstart, but the version used in Ubuntu 12.04 does restart Glassfish if it -stops during <code>pre-stop</code>.)</p> -<p>Yes, this does make it impossible to stop Glassfish, ever, unless you set a -respawn limit.</p> -<p>Fortunately, you don't actually want to use <code>respawn</code> to manage availability. -The <code>respawn</code> mode cripples your ability to manage the service “out of band” -by forcing Upstart to restart it as a daemon every time it stops for any -reason. This means you cannot stop a server with <code>SIGTERM</code> or <code>SIGKILL</code>; it'll -immediately start again.</p> -<h2 id="initctl-reload"><code>initctl reload</code></h2> -<p>It sends <code>SIGHUP</code>. This does not reload Glassfish's configuration. Deal with -it; use <code>initctl restart</code> or <code>asadmin restart-domain</code> instead. Most of -Glassfish's configuration can be changed on the fly with <code>asadmin set</code> or -other commands anyways, so this is not a big limitation.</p> -<h2 id="instances">Instances</h2> -<p>Upstart supports “instances” of a service. This slots nicely into Glassfish's -ability to host multiple domains and instances on the same physical hardware. -I ended up with a generic <code>glassfish-domain.conf</code> Upstart configuration:</p> -<pre><code>description "Glassfish DAS" -console log - -instance $DOMAIN - -setuid glassfish -setgid glassfish -umask 0022 -chdir /opt/glassfish3 - -exec /usr/bin/java -jar /opt/glassfish3/glassfish/modules/glassfish.jar -domain "${DOMAIN}" - -pre-stop exec /opt/glassfish3/bin/asadmin stop-domain "${DOMAIN}" -</code></pre> -<p>Combined with a per-domain wrapper:</p> -<pre><code>description "Glassfish 'example' domain" -console log - -# Consider using runlevels here. -start on started networking -stop on deconfiguring-networking - -pre-start script - start glassfish-domain DOMAIN=example -end script - -post-stop script - stop glassfish-domain DOMAIN=example -end script -</code></pre> -<h2 id="possible-refinements">Possible refinements</h2> -<ul> -<li> -<p>Pull system properties and VM flags from the domain's own <code>domain.xml</code> - correctly. It might be possible to abuse the (undocumented, unsupported, but - helpful) <code>--_dry-run</code> argument from <code>asadmin start-domain</code> for this, or it - might be necessary to parse <code>domain.xml</code> manually, or it may be possible to - exploit parts of Glassfish itself for this.</p> -</li> -<li> -<p>The <code>asadmin</code> cwd is actually the domain's <code>config</code> dir, not the Glassfish - installation root.</p> -</li> -<li> -<p>Something something something password files.</p> -</li> -<li> -<p>Syslog and logrotate integration would be useful. The configurations above - spew Glassfish's startup output and stdout to - <code>/var/log/upstart/glassfish-domain-FOO.log</code>, which may not be rotated by - default.</p> -</li> -</ul> - </div> - - - -<div id="comments"> -<div id="disqus_thread"></div> -<script type="text/javascript"> - /* * * CONFIGURATION VARIABLES: EDIT BEFORE PASTING INTO YOUR WEBPAGE * * */ - var disqus_shortname = 'grimoire'; // required: replace example with your forum shortname - - /* * * DON'T EDIT BELOW THIS LINE * * */ - (function() { - var dsq = document.createElement('script'); dsq.type = 'text/javascript'; dsq.async = true; - dsq.src = 'http://' + disqus_shortname + '.disqus.com/embed.js'; - (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(dsq); - })(); -</script> -<noscript>Please enable JavaScript to view the <a href="http://disqus.com/?ref_noscript">comments powered by Disqus.</a></noscript> -<a href="http://disqus.com" class="dsq-brlink">comments powered by <span class="logo-disqus">Disqus</span></a> -</div> - - - - <div id="footer"> - <p> - - The Codex — - - Powered by <a href="http://markdoc.org/">Markdoc</a>. - -<a href="https://bitbucket.org/ojacobson/grimoire.ca/src/master/wiki/devops/glassfish-and-upstart.md">See this page on Bitbucket</a> (<a href="https://bitbucket.org/ojacobson/grimoire.ca/history-node/master/wiki/devops/glassfish-and-upstart.md">history</a>). - - </p> - </div> - -</div> -</body> -</html>
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