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>
Add reference to https://github.com/vmware/docker-volume-vsphere to Docker's list of plugins.
This is an officially supported plugin from VMware.
Signed-off-by: Ritesh H Shukla <sritesh@vmware.com>
The -f flag on docker tag has been deprecated in docker 1.10 and
is expected to be removed in docker 1.12.
This fix removed the -f flag on docker tag and also updated
deprecated.md.
NOTE: A separate pull request for engine-api has been opened to
cover the related changes.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This does a minor cleanup of the logging driver
documentation;
- Add a table-header to the driver-options
table.
- Add language hints to code-blocks to
prevent incorrect highlighting
- Wrap some code examples so that they
fit in the default layout
- Wrap text to 80-chars
- Fix ordering in menu
- Some minor rewording
We should still create separate pages
for all available drivers (for example,
json-file, syslog, and GELF don't have
their own configuration page)
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>
Since 1.9, the following short variant options have been
deprecated in favor of their long variants:
`docker run -c (--cpu-shares)`
`docker build -c (--cpu-shares)`
`docker create -c (--cpu-shares)`
`docker update -c (--cpu-shares)`
However, `-c` is still widely used and is considered as
a convenient option for swarm (see #16271).
This fix undeprecated the command line short
variant options of `-c` and updated the deprecated.md.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Updated documents markdown file on Debian installation.
Added details on the fact that backports are necessary on Wheezy as discussed in issue #16878
Signed-off-by: George Hafiz <george@hafiz.uk>
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>
