Previously a crashed container would stay down, regardless of exit status. In some cases, it may be useful to restart the container. For example, an application may not be correctly implementing their error handling, or the crash may be caused by a transient error.
By setting the restart policy to `on-failure:N` - where N is a number of max restarts - we can help developers guard against crashing applications. Note that this is not a replacement for proper error handling, nor does this include notifications to a developer when a container is restarted. Those patterns should be implemented application side, or via a feature request to docker.
The value is configurable at the app-level by setting DOKKU_RESTART_LIMIT to a number. By default, containers will be restarted a max of 10 times. If a container crashes during the check-deploy plugin trigger, then the deploy will be marked as a failure.
Closes#216Closes#398Closes#1327
This should theoretically be safe, as "--export" forces the `dokku config` command to return 0 in all cases, and it should only output lines that are "valid" environment variables
As briefly discussed in #1425, source the `common/functions` file via an
absolute path, rather than determining the relative path by using
`dirname`. 3rd-party plugins should follow suit and use the new
`$PLUGIN_PATH` convention too.
Setting `DOKKU_SKIP_ALL_CHECKS` globally or for a given app will skip
all checks.
Setting `DOKKU_SKIP_DEFAULT_CHECKS` globally or for a given app will skip
default checks only.
ATTEMPTS=0 means don't run the checks. Useful if you want to skip the checks and can be overridden by DOKKU_CHECKS_ATTEMPTS
ATTEMPTS=1 means run only once
- Specify how long to wait before running first check
- Specify timeout for each check
- Check specific hosts, e.g. http://signin.example.com
- Check both HTTP and HTTPS resources
This change makes Dokku start up the new container, run a set of checks
against it, and only switch traffic over to the new containers if all
checks complete successfully. No requests are dropped during the switch
over.
To specify checks, add a CHECKS file to the root of your project
directory. This is a text file with one line per check. Empty lines and
lines starting with # are ignored.
A check is a relative URL and may be followed by expected content from
the page, for example:
/about Our Amazing Team
Even if you don’t use any checks, this change will prevent downtime
during switching from old to new container.
See: https://labnotes.org/zero-downtime-deploy-with-dokku/
