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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2023-01-09 11:09:14 +0000 |
|---|---|---|
| committer | Laurent Bercot <ska@appnovation.com> | 2023-01-09 11:09:14 +0000 |
| commit | 09750ce3525129a676dec4f579aea3ad2eca1b19 (patch) | |
| tree | acae6b5f47914d7ed85bbb8fe9780ed34a85cfd0 /doc/s6-instance-maker.html | |
| parent | 191b46491407632f2431c46eab97dbf5543fa26d (diff) | |
| download | s6-09750ce3525129a676dec4f579aea3ad2eca1b19.tar.xz | |
Add instances implementation (still needs testing)
Signed-off-by: Laurent Bercot <ska@appnovation.com>
Diffstat (limited to 'doc/s6-instance-maker.html')
| -rw-r--r-- | doc/s6-instance-maker.html | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/doc/s6-instance-maker.html b/doc/s6-instance-maker.html new file mode 100644 index 0000000..2eb0f4e --- /dev/null +++ b/doc/s6-instance-maker.html @@ -0,0 +1,203 @@ +<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-instance-maker program</title> + <meta name="Description" content="s6: the s6-instance-maker program" /> + <meta name="Keywords" content="s6 command s6-instance-maker instance dynamic instantiation instanced services" /> + <!-- <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 s6-instance-maker program </h1> + +<p> +s6-instance-maker creates a <a href="servicedir.html">service directory</a> +implementing an <a href="instances.html">instanced service</a>. Give it a +templated service directory describing how to run an instance of a service, +and it will create a different service directory that can launch and +manage several instances; each of these instances will be running a +copy of the service directory you gave. +</p> + +<p> + Alternatively, s6-instance-maker can create source definition directories +for the <a href="//skarnet.org/software/s6-rc/">s6-rc</a> service manager. +</p> + +<h2> Interface </h2> + +<pre> + s6-instance-maker \ + [ -c <em>maxinstances</em> ] \ + [ -r <em>service</em>[/<em>logger</em>[/<em>pipeline</em>]] ] \ + [ -u <em>user</em> ] \ + [ -l <em>loguser</em> ] \ + [ -L <em>logdir</em> ] \ + [ -t <em>stamptype</em> ] \ + [ -n <em>nfiles</em> ] \ + [ -s <em>filesize</em> ] \ + [ -S <em>maxsize</em> ] \ + [ -P <em>prefix</em> ] \ + template dir +</pre> + +<p> +s6-instance-maker creates a service directory in <em>dir</em>. The +created service will be a supervisor for a set of instances (initially empty) +each running a copy of the service directory given in <em>template</em>. +</p> + +<p> +s6-instance-maker is an <em>offline</em> tool: it is run before you need +instances. Once the created service directory is live, i.e. there is a +supervisor running on it, then you can create, delete, or control +individual instances via the +<a href="s6-instance-create.html">s6-instance-create</a>, +<a href="s6-instance-delete.html">s6-instance-delete</a> and +<a href="s6-instance-control.html">s6-instance-control</a> <em>online</em> +tools, that work with active services. +</p> + +<h2> Exit codes </h2> + +<ul> + <li> 0: success </li> + <li> 100: wrong usage </li> + <li> 111: system call failed </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-c</tt> <em>max</em> : Plan for a maximum of <em>max</em> +instances. Default is <strong>500</strong>. You can't set it lower than 2 or +higher than 90000. If your template service directory is logged, it's unadvisable +to set this above the default. </li> <br> + + <li> <tt>-r</tt> <em>service</em>[/<em>logger</em>[/<em>pipeline</em>]] : +create <a href="//skarnet.org/software/s6-rc">s6-rc</a> source definition directories. +When this option is given, <em>dir</em> is not created as a service directory, but +as a directory containing at least one service: <em>dir</em>/<em>service</em>. +<em>dir</em> is suitable as a source argument to +<a href="//skarnet.org/software/s6-rc/s6-rc-compile.html">s6-rc-compile</a>. If +a <em>logger</em> part is given, then a second service, <em>dir</em>/<em>logger</em>, +is also created, as a consumer for <em>dir</em>/<em>service</em>, and the <tt>-L</tt> +option must also be used, to provide a directory to store the logs into. If the +<tt>/</tt><em>pipeline</em> part is also given, <em>pipeline</em> +is used as a name for a bundle containing both <em>service</em> and <em>logger</em>. +When the <tt>-r</tt> option is not given at all, <em>dir</em> is a regular service +directory for direct inclusion (or linking) in a host +<a href="scandir.html">scan directory</a>, and if the <tt>-L</tt> option is given +then the logger for the instance supervisor and all its instances is declared in +<em>dir</em><tt>/log</tt>). </li> <br> + + <li> <tt>-u</tt> <em>user</em> : run the instance supervisor, and all +of the instances, as user <em>user</em>. This option should only be used when the +supervision tree that will host the instanced service is run as root. The default +is that the service runs as the same user as the host supervision tree. </li> <br> + + <li> <tt>-l</tt> <em>loguser</em> : run the logger of the instance +supervisor, if any (see <tt>-L</tt> below) as user <em>loguser</em>. This option +should only be used when the +supervision tree that will host the instanced service is run as root. The default +is that the logger runs as the same user as the host supervision tree. </li> <br> + + <li> <tt>-L</tt> <em>logdir</em> : make the service logged via +<a href="s6-log.html">s6-log</a>, and ensure its log messages go into <em>logdir</em>. +Error messages from the instance supervisor as well as from every instance will +be logged to <em>logdir</em>. If this option is not given, these error messages +will fall through to the host supervision tree's catch-all logger, if any, +or standard error otherwise. <br> +The options listed below are only used to configured the logger and are meaningless +if <tt>-L</tt> is not given. </li> <br> + + <li> <tt>-t</tt> <em>stamptype</em> : how +logs are timestamped in <em>logdir</em>. 0 means no timestamp, 1 means +<a href="https://cr.yp.to/libtai/tai64.html">external TAI64N format</a>, +2 means +<a href="https://www.iso.org/iso/home/standards/iso8601.htm">ISO 8601 format</a>, +and 3 means both. Default is <strong><tt>1</tt></strong>. </li> <br> + + <li> <tt>-n</tt> <em>nfiles</em> : maximum number of archive files +in <em>logdir</em>. Default is <strong><tt>10</tt></strong>. </li> <br> + + <li> <tt>-s</tt> <em>filesize</em> : maximum size of the <tt>current</tt> +file (and archive files) in <em>logdir</em>. Default is <strong><tt>1000000</tt></strong>. </li> <br> + + <li> <tt>-S</tt> <em>maxsize</em> : maximum total size of the +archives in <em>logdir</em>. Default is <strong><tt>0</tt></strong>, +meaning no limits apart from those enforced by the <tt>-n</tt> and +<tt>-s</tt> options. </li> <br> + + <li> <tt>-P</tt> <em>prefix</em> : when logging to <em>logdir</em>, +prefix logged lines with the <em>prefix</em> string. Default is no prefix. </li> +</ul> + +<h2> The templated service directory </h2> + +<p> + <em>template</em> should be a directory that looks exactly like a service +directory. It will not be live, i.e. at no point will <em>template</em> +itself be supervised; instead, a copy of it is stored under <em>dir</em> +(and a copy of that copy will be used for every instance of the service). +You can safely move or delete <em>template</em> after running +s6-instance-maker. +</p> + +<p> + To differentiate between instances, the <tt>run</tt> and <tt>finish</tt> +script in <em>template</em> should take one additional argument (the +first argument for <tt>run</tt> and the third argument for <tt>finish</tt>). +This argument will be the name of the instance, as provided by the +<a href="s6-instance-create.html">s6-instance-create</a> invocation. +</p> + +<h2> Logging </h2> + +<p> + The service is logged: its stderr and stdout are piped to an +<a href="s6-log.html">s6-log</a> process running as <em>loguser</em> and +writing to the <em>logdir</em> directory. This logger is the catch-all logger +for the supervision tree owned by <em>user</em>; it is recommended to make +<em>loguser</em> distinct from <em>user</em>, and to have <em>logdir</em> +in a place that is <strong>not</strong> under the control of <em>user</em>. +If <em>user</em> wants to keep control of their logs, they can declare a +logger for each of their services. +</p> + +<p> + If <em>template</em> has a <em>log</em> subdirectory, then each instance +will have its own dedicated logger. The <tt>run</tt> and <tt>finish</tt> +scripts for the logger of an instance named <em>name</em> will be called +with an additional argument of <tt><em>name</em>/log</tt>. They should +make use of this, to ensure loggers are properly differentiated between +instances: for instance, it is not possible to run several +<a href="s6-log.html">s6-log</a> processes on the same log directory, +so an instance logger script containing an invocation of s6-log on a fixed +logdir will fail as soon as there are 2 instances. +</p> + +<h2> Notes </h2> + +<ul> + <li> s6-instance-maker makes use of the fact that +<a href="//skarnet.org/software/execline/">execline</a> scripts are much +easier to generate programmatically and to harden than shell scripts, so it is only +built if s6 is built with <a href="//skarnet.org/software/execline/">execline</a> +support - i.e. the <tt>--disable-execline</tt> switch has <em>not</em> been given +to configure. </li> + <li> If s6-instance-maker encounters failure (and exits 111), it does not clean up +the directories it created. Make sure to always test s6-usertree-maker's return code +and clean up after it if needed. </li> +</ul> + +</body> +</html> |