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Taikun OCP Guide

Table of Contents

Controlling Glance Servers

This section describes the ways to start, stop, and reload Glance’s
server programs.

Starting a server

There are two ways to start a Glance server:

  • Manually calling the server program
  • Using the glance-control server daemon wrapper
    program

We recommend using the second method.

Manually starting the server

The first is by directly calling the server program, passing in
command-line options and a single argument for a
paste.deploy configuration file to use when configuring the
server application.

Note

Glance ships with an etc/ directory that contains sample
paste.deploy configuration files that you can copy to a
standard configuration directory and adapt for your own uses.
Specifically, bind_host must be set properly.

If you do not specify a configuration
file on the command line, Glance will do its best to locate a
configuration file in one of the following directories, stopping at the
first config file it finds:

  • $CWD
  • ~/.glance
  • ~/
  • /etc/glance
  • /etc

The filename that is searched for depends on the server application
name. So, if you are starting up the API server,
glance-api.conf is searched for.

If no configuration file is found, you will see an error, like:

$ glance-api
ERROR: Unable to locate any configuration file. Cannot load application glance-api

Here is an example showing how you can manually start the
glance-api server in a shell.:

$ sudo glance-api --config-file glance-api.conf --debug &
jsuh@mc-ats1:~$ 2011-04-13 14:50:12    DEBUG [glance-api] ********************************************************************************
2011-04-13 14:50:12    DEBUG [glance-api] Configuration options gathered from config file:
2011-04-13 14:50:12    DEBUG [glance-api] /home/jsuh/glance-api.conf
2011-04-13 14:50:12    DEBUG [glance-api] ================================================
2011-04-13 14:50:12    DEBUG [glance-api] bind_host                      65.114.169.29
2011-04-13 14:50:12    DEBUG [glance-api] bind_port                      9292
2011-04-13 14:50:12    DEBUG [glance-api] debug                          True
2011-04-13 14:50:12    DEBUG [glance-api] default_store                  file
2011-04-13 14:50:12    DEBUG [glance-api] filesystem_store_datadir       /home/jsuh/images/
2011-04-13 14:50:12    DEBUG [glance-api] ********************************************************************************
2011-04-13 14:50:12    DEBUG [routes.middleware] Initialized with method overriding = True, and path info altering = True
2011-04-13 14:50:12    DEBUG [eventlet.wsgi.server] (21354) wsgi starting up on http://65.114.169.29:9292/

$ ps aux | grep glance
root     20009  0.7  0.1  12744  9148 pts/1    S    12:47   0:00 /usr/bin/python /usr/bin/glance-api glance-api.conf --debug
jsuh     20017  0.0  0.0   3368   744 pts/1    S+   12:47   0:00 grep glance

Simply supply the configuration file as the parameter to the
--config-file option (the etc/glance-api.conf
sample configuration file was used in the above example) and then any
other options you want to use. (--debug was used above to
show some of the debugging output that the server shows when starting
up. Call the server program with --help to see all
available options you can specify on the command line.)

For more information on configuring the server via the
paste.deploy configuration files, see the section entitled
Configuring Glance servers <configuring>

Note that the server daemonizes itself
by using the standard shell backgrounding indicator, &,
in the previous example. For most use cases, we recommend using the
glance-control server daemon wrapper for daemonizing. See
below for more details on daemonization with
glance-control.

Using the
glance-control program to start the server

The second way to start up a Glance server is to use the
glance-control program. glance-control is a
wrapper script that allows the user to start, stop, restart, and reload
the other Glance server programs in a fashion that is more conducive to
automation and scripting.

Servers started via the glance-control program are
always daemonized, meaning that the
server program process runs in the background.

To start a Glance server with glance-control, simply
call glance-control with a server and the word “start”,
followed by any command-line options you wish to provide. Start the
server with glance-control in the following way:

$ sudo glance-control [OPTIONS] <SERVER> start [CONFPATH]

Note

You must use the sudo program to run
glance-control currently, as the pid files for the server
programs are written to /var/run/glance/

Here is an example that shows how to start the
glance-api server with the glance-control
wrapper script. :

$ sudo glance-control api start glance-api.conf
Starting glance-api with /home/jsuh/glance.conf

$ ps aux | grep glance
root     20038  4.0  0.1  12728  9116 ?        Ss   12:51   0:00 /usr/bin/python /usr/bin/glance-api /home/jsuh/glance-api.conf
jsuh     20042  0.0  0.0   3368   744 pts/1    S+   12:51   0:00 grep glance

The same configuration files are used by glance-control
to start the Glance server programs, and you can specify (as the example
above shows) a configuration file when starting the server.

In order for your launched glance service to be monitored for
unexpected death and respawned if necessary, use the following
option:

$ sudo glance-control [service] start --respawn ...

Note that this will cause glance-control itself to
remain running. Also note that deliberately stopped services are not
respawned, neither are rapidly bouncing services (where process death
occurred within one second of the last launch).

By default, output from glance services is discarded when launched
with glance-control. In order to capture such output via
syslog, use the following option:

$ sudo glance-control --capture-output ...

Stopping a server

If you started a Glance server manually and did not use the
& backgrounding function, simply send a terminate
signal to the server process by typing Ctrl-C

If you started the Glance server using the
glance-control program, you can use the
glance-control program to stop it. Simply do the
following:

$ sudo glance-control <SERVER> stop

as this example shows:

$ sudo glance-control api stop
Stopping glance-api  pid: 17602  signal: 15

Restarting a server

You can restart a server with the glance-control
program, as demonstrated here:

$ sudo glance-control api restart etc/glance-api.conf
Stopping glance-api  pid: 17611  signal: 15
Starting glance-api with /home/jpipes/repos/glance/trunk/etc/glance-api.conf

Reloading a server

You can reload a server with the glance-control program,
as demonstrated here:

$ sudo glance-control api reload
Reloading glance-api (pid 18506) with signal(1)

A reload sends a SIGHUP signal to the master process and causes new
configuration settings to be picked up without any interruption to the
running service (provided neither bind_host or bind_port has
changed).

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