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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2018-03-21 18:00:10 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2018-03-21 18:00:10 +0000 |
| commit | 75c4223a7f5a8a073ba0d898ef9d841fdaef2f63 (patch) | |
| tree | d024c08659674117134314e67b4ff825ae51c1d9 /doc/s6-permafailon.html | |
| parent | 91eba4b27017c3b7bf0d0bb548a12a694ed51a3b (diff) | |
| download | s6-75c4223a7f5a8a073ba0d898ef9d841fdaef2f63.tar.xz | |
Add s6-svdt-clear, s6-permafailon
Diffstat (limited to 'doc/s6-permafailon.html')
| -rw-r--r-- | doc/s6-permafailon.html | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/doc/s6-permafailon.html b/doc/s6-permafailon.html new file mode 100644 index 0000000..f749d5f --- /dev/null +++ b/doc/s6-permafailon.html @@ -0,0 +1,98 @@ +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-permafailon program</title> + <meta name="Description" content="s6: the s6-permafailon program" /> + <meta name="Keywords" content="s6 supervision finish permanent failure service" /> + <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6</a><br /> +<a href="//skarnet.org/software/">Software</a><br /> +<a href="//skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>s6-permafailon</tt> program </h1> + +<p> +<tt>s6-permafailon</tt> is a program that is meant to be used +in the <tt>./finish</tt> script of a +<a href="servicedir.html">service directory</a> supervised by +<a href="s6-supervise.html">s6-supervise</a>. When used, it +reads and analyses the death tally of a service (i.e. the recent +process death events that happened), and if the death tally +matches a given pattern, it causes <em>permanent failure</em> +of the service, i.e. it tells the supervisor not to try and +restart it. +</p> + +<h2> Interface </h2> + +<pre> + s6-permafailon <em>secs</em> <em>deathcount</em> <em>events</em> <em>prog...</em> +</pre> + +<ul> + <li> <tt>s6-permafailon</tt> must have the service directory of the +tested service as its current directory. This is the default if it is +called from the <tt>finish</tt> script of the service. </li> + <li> It reads the <em>death tally</em> of the service, which is +maintained by <a href="s6-supervise.html">s6-supervise</a>. </li> + <li> If the supervised process has died at least <em>deathcount</em> +times in the last <em>secs</em> seconds with a cause listed in +<em>events</em>, then <tt>s6-permafailon</tt> exits 125. </li> + <li> Else <tt>s6-permafailon</tt> execs into <em>prog...</em>. </li> +</ul> + +<p> + <em>events</em> is a comma-separated list of events. An event can be +one of the following: +</p> + +<ul> + <li> An exit code, which is an integer between 0 and 255. Example: <tt>1</tt> </li> + <li> An exit code interval, which is two exit codes separated by a dash. Example: <tt>1-50</tt> </li> + <li> A signal name, or a signal number preceded by "SIG". Examples: <tt>SIGTERM</tt>, <tt>sigabrt</tt>, <tt>sig11</tt> </li> +</ul> + +<h2> Usage </h2> + +<ul> + <li> <a href="s6-supervise.html">s6-supervise</a> detects when the <tt>./finish</tt> +script of its service exits 125, and stops respawning the service. So, if the +<tt>./finish</tt> script is a chain-loading command line starting with a +<tt>s6-permafailon</tt> invocation (or containing such an invocation), when +<tt>s6-permafailon</tt> exits 125, then the <tt>./finish</tt> script also +exits 125 (because it is the same process), and the service is then marked as +failing permanently. </li> + <li> The <tt>./finish</tt> script is <em>naturally</em> a chain-loading +command line if it is written in the +<a href="//skarnet.org/software/execline/">execline</a> language. It +can also be made into a chain-loading command line from a shell script by using +<tt>exec s6-permafailon secs deathcount events rest-of-chainloading-cmdline...</tt> </li> + <li> Multiple invocations of <tt>s6-permafailon</tt> can be chained, in order +to test several death patterns. </li> + <li> If a permanent failure is triggered and <em>secs</em> is high, it is +possible that when the administrator manually launches the service again, +the next death triggers a permanent failure again. If this is not wanted, +the administrator should clear the death tally with the +<a href="s6-svdt-clear.html">s6-svdt-clear</a> command. </li> + <li> The current death tally can be viewed via the <a href="s6-svdt.html">s6-svdt</a> +command. </li> +</ul> + +<h2> Example </h2> + +<p> + <tt>s6-permafailon 60 5 1,101-103,SIGSEGV,SIBBUS <em>prog...</em></tt> +will exit 125 if the service has died 5 times in the last 60 seconds with +an exit code of 1, 101, 102 or 103, a SIGSEGV or a SIGBUS. Else it will +chainload into the <em>prog...</em> command line. +</p> + +</body> +</html> |