Allows for a plugin type that can be used to scrape metrics.
This is useful because metrics are not neccessarily at a standard
location... `--metrics-addr` must be set, and must currently be a TCP
socket.
Even if metrics are done via a unix socket, there's no guarentee where
the socket may be located on the system, making bind-mounting such a
socket into a container difficult (and racey, failure-prone on daemon
restart).
Metrics plugins side-step this issue by always listening on a unix
socket and then bind-mounting that into a known path in the plugin
container.
Note there has been similar work in the past (and ultimately punted at
the time) for consistent access to the Docker API from within a
container.
Why not add metrics to the Docker API and just provide a plugin with
access to the Docker API? Certainly this can be useful, but gives a lot
of control/access to a plugin that may only need the metrics. We can
look at supporting API plugins separately for this reason.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Logging plugins use the same HTTP interface as other plugins for basic
command operations meanwhile actual logging operations are handled (on
Unix) via a fifo.
The plugin interface looks like so:
```go
type loggingPlugin interface {
StartLogging(fifoPath string, loggingContext Context) error
StopLogging(fifoPath)
```
This means a plugin must implement `LoggingDriver.StartLogging` and
`LoggingDriver.StopLogging` endpoints and be able to consume the passed
in fifo.
Logs are sent via stream encoder to the fifo encoded with protobuf.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Tested using global-net-plugin-ipc which sets PidHost in config.json.
Plugins might need access to host pid namespace. Add support for that.
Tested using aragunathan/global-net-plugin-ipc which sets "pidhost" in
config.json. Observed using `readlink /proc/self/ns/pid` that plugin and
host have the same ns.
Signed-off-by: Anusha Ragunathan <anusha.ragunathan@docker.com>
Plugins might need access to host ipc namespace. A good usecase is
a volume plugin running iscsi multipath commands that need access to
host kernel locks.
Tested with a custom plugin (aragunathan/global-net-plugin-full) that's
built with `"ipchost" : true` in config.json. Observed using
`readlink /proc/self/ns/ipc` that plugin and host have the same ns.
Signed-off-by: Anusha Ragunathan <anusha.ragunathan@docker.com>
This persists the "propagated mount" for plugins outside the main
rootfs. This enables `docker plugin upgrade` to not remove potentially
important data during upgrade rather than forcing plugin authors to hard
code a host path to persist data to.
Also migrates old plugins that have a propagated mount which is in the
rootfs on daemon startup.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This fix adds `--filter capability=[volumedriver|authz]` to `docker plugin ls`.
The related docs has been updated.
An integration test has been added.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Legacy plugins expect host-relative paths (such as for Volume.Mount).
However, a containerized plugin cannot respond with a host-relative
path. Therefore, this commit modifies new volume plugins' paths in Mount
and List to prepend the container's rootfs path.
This introduces a new PropagatedMount field in the Plugin Config.
When it is set for volume plugins, RootfsPropagation is set to rshared
and the path specified by PropagatedMount is bind-mounted with rshared
prior to launching the container. This is so that the daemon code can
access the paths returned by the plugin from the host mount namespace.
Signed-off-by: Tibor Vass <tibor@docker.com>
Brian Goff
yuexiao-wang
Anusha Ragunathan
Yong Tang
Tibor Vass
Victor Vieux
lixiaobing10051267
Victor Vieux
Misty Stanley-Jones
Riyaz Faizullabhoy