Man page improvement - lxc.start.order

n8v8r · June 12, 2018, 7:58am

Having looked into Linux Containers - LXC - Manpages - lxc.container.conf.5

lxc.start.order
An integer used to sort the containers when auto-starting a series of containers at once.

AUTOSTART AND SYSTEM BOOT
... The startup will be in order of lxc.start.order.

The leaves one to guesswork of how the integer is interpreted, e.g. whether 0 is lowest or highest priority or even whether 0 might be a special value (like perhaps disabling)

It thus requires a (potential) user to sour other sources (e.g. LXC 1.0: Your second container [2/10] | Stéphane Graber's website) to discover

priority of the container, higher value means starts earlier

I suppose such should be rather pointed out in the man pages.

simos · June 12, 2018, 9:51am

I would have guessed that lower number starts earlier.
Are you familiar with git, GitHub, in order to create a pull request with a clarification?

n8v8r · June 12, 2018, 10:16am

My sentiments exactly, my logic would also have been that 0 is either the highest priority, or if representing a special value such as disable for instance than 1 being the highest priority and incrementing integer’s value is decreasing the priority but apparently it is the other way around.

Not sure if it warrants a clarification on Github really but rather a more expansive explanation at the man page. Have updated the previous post with the source of the information, being a blog of @stgraber.

Unless this changed over time from lxc 1, which the blog post from 2013 is based on, to today’s lxc 3 version

simos · June 12, 2018, 12:01pm

I am on mobile now. As far as I understand, the man pages are on the lxc git repository on GitHub. It should be GitHub.com/lxc/lxc
You can edit the manpage and submit a pull request to accept the change.

n8v8r · June 12, 2018, 12:30pm

Seems not located there. All I could trace https://github.com/lxc/linuxcontainers.org/tree/master/manpages/lxc but there are only placeholders for some languages.

simos · June 12, 2018, 1:33pm

It’s here,

github.com

lxc/lxc/blob/master/doc/lxc.container.conf.sgml.in#L2359


  </term>
  <listitem>
    <para>
      How long to wait (in seconds) after the container is
      started before starting the next one.
    </para>
  </listitem>
</varlistentry>
<varlistentry>
  <term>
    <option>lxc.start.order</option>
  </term>
  <listitem>
    <para>
      An integer used to sort the containers when auto-starting
      a series of containers at once.
    </para>
  </listitem>
</varlistentry>
<varlistentry>
  <term>

The man pages are created from SGML, which should not be difficult to edit.

n8v8r · June 12, 2018, 1:57pm

Thank you for the pointer! Prior editing though it would be good to know whether an interger of 0 serves a special purpose or is just the lowest priority.

simos · June 12, 2018, 4:23pm

Searching through the source code, shows only the following occurence:

github.com

lxc/lxc/blob/master/src/lxc/tools/lxc_autostart.c#L308


	}


	if (lxc_safe_int(value, &ret) < 0)
		printf("Could not parse config item.\n");


	free(value);


	return ret;
}


static int cmporder(const void *p1, const void *p2)
{
	struct lxc_container *c1 = *(struct lxc_container **)p1;
	struct lxc_container *c2 = *(struct lxc_container **)p2;


	int c1_order = get_config_integer(c1, "lxc.start.order");
	int c2_order = get_config_integer(c2, "lxc.start.order");


	if (c1_order == c2_order)
		return strcmp(c1->name, c2->name);

Therefore, the number there is only used to compare between containers. 0 has no special significance.