This PR adds support for user-defined health-check probes for Docker
containers. It adds a `HEALTHCHECK` instruction to the Dockerfile syntax plus
some corresponding "docker run" options. It can be used with a restart policy
to automatically restart a container if the check fails.
The `HEALTHCHECK` instruction has two forms:
* `HEALTHCHECK [OPTIONS] CMD command` (check container health by running a command inside the container)
* `HEALTHCHECK NONE` (disable any healthcheck inherited from the base image)
The `HEALTHCHECK` instruction tells Docker how to test a container to check that
it is still working. This can detect cases such as a web server that is stuck in
an infinite loop and unable to handle new connections, even though the server
process is still running.
When a container has a healthcheck specified, it has a _health status_ in
addition to its normal status. This status is initially `starting`. Whenever a
health check passes, it becomes `healthy` (whatever state it was previously in).
After a certain number of consecutive failures, it becomes `unhealthy`.
The options that can appear before `CMD` are:
* `--interval=DURATION` (default: `30s`)
* `--timeout=DURATION` (default: `30s`)
* `--retries=N` (default: `1`)
The health check will first run **interval** seconds after the container is
started, and then again **interval** seconds after each previous check completes.
If a single run of the check takes longer than **timeout** seconds then the check
is considered to have failed.
It takes **retries** consecutive failures of the health check for the container
to be considered `unhealthy`.
There can only be one `HEALTHCHECK` instruction in a Dockerfile. If you list
more than one then only the last `HEALTHCHECK` will take effect.
The command after the `CMD` keyword can be either a shell command (e.g. `HEALTHCHECK
CMD /bin/check-running`) or an _exec_ array (as with other Dockerfile commands;
see e.g. `ENTRYPOINT` for details).
The command's exit status indicates the health status of the container.
The possible values are:
- 0: success - the container is healthy and ready for use
- 1: unhealthy - the container is not working correctly
- 2: starting - the container is not ready for use yet, but is working correctly
If the probe returns 2 ("starting") when the container has already moved out of the
"starting" state then it is treated as "unhealthy" instead.
For example, to check every five minutes or so that a web-server is able to
serve the site's main page within three seconds:
HEALTHCHECK --interval=5m --timeout=3s \
CMD curl -f http://localhost/ || exit 1
To help debug failing probes, any output text (UTF-8 encoded) that the command writes
on stdout or stderr will be stored in the health status and can be queried with
`docker inspect`. Such output should be kept short (only the first 4096 bytes
are stored currently).
When the health status of a container changes, a `health_status` event is
generated with the new status. The health status is also displayed in the
`docker ps` output.
Signed-off-by: Thomas Leonard <thomas.leonard@docker.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This fix fixes an error in documentation (dockerd.md). In the
example given by dockerd.md, the option `cluster-store-opts`
is assigned with an array but this option can only be assigned
as a map.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Add support for two now filter on the `images` command : `before` and
`since`. They work the same as the one on the `ps` command but for
images.
$ docker images --filter before=myimage
# display all images older than myimage
$ docker images --filter since=myimage
# display all images younger than myimage
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
This fix tries to address the issue raised in #21976 and allows
the options of `--add-host` and `--net=host` to work at the same time.
The documentation has been updated and additional tests have been
added to cover this change.
This fix fixes#21976.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This fix tries to address the issue raised in #21976 and allows
the options of `--dns`, `--dns-search`, `--dns-opt` and `--net=host`
to work at the same time.
The documentation has been updated and additional tests have been
added to cover this change.
This fix fixes#21976.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This fix tries to cover the issue raised in #22463 by adding
filter for events emitted by docker daemon so that user could
utilize filter to receive events of interest.
Documentations have been updated for this fix.
Additional tests have been added to cover the changes in this fix.
This fix fixes#22463.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This fix tries to cover the issue raised in #22463 by emitting
events for docker daemon so that user could be notified by
scenarios like config reload, etc.
This fix adds the `daemon reload`, and events for docker daemon.
Additional tests have been added to cover the changes in this fix.
This fix fixes#22463.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
- Add link to valid image name and tag formats in referenced files
- Per review comments, updated docs to remove reference to `USERNAME` and
`REGISTRYHOST`.
- Per review comment, removed links from man page.
- Per review comment, added and updated examples on `docker tag`
Signed-off-by: Subhajit Ghosh <isubuz.g@gmail.com>
Automatic translation of MLS labels is currently not
supported, so should not be documented as an example.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The filtering is made server-side, and the following filters are
supported:
* is-official (boolean)
* is-automated (boolean)
* has-stars (integer)
Signed-off-by: Fabrizio Soppelsa <fsoppelsa@mirantis.com>
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Replace Note with a new secion, reduce characters in
per line in 80. Add statement suggested by
https://github.com/thaJeztah
Signed-off-by: Lin Lu <doraalin@163.com>
