Use `pkg/discovery` to provide nodes discovery between daemon instances.
The functionality is driven by two different command-line flags: the
experimental `--cluster-store` (previously `--kv-store`) and
`--cluster-advertise`. It can be used in two ways by interested
components:
1. Externally by calling the `/info` API and examining the cluster store
field. The `pkg/discovery` package can then be used to hit the same
endpoint and watch for appearing or disappearing nodes. That is the
method that will for example be used by Swarm.
2. Internally by using the `Daemon.discoveryWatcher` instance. That is
the method that will for example be used by libnetwork.
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
* Update format for 'Note:' to match other pages.
* Add link to Go's RFC3339Nano timestamp information.
Signed-off-by: Charles Chan <charleswhchan@users.noreply.github.com>
This way provide both Time and TimeNano in the event. For the display of
the JSONMessage, use either, but prefer TimeNano Proving only TimeNano
would break Subscribers that are using the `Time` field, so both are set
for backwards compatibility.
The events logging uses nano formatting, but only provides a Unix()
time, therefor ordering may get lost in the output. Example:
```
2015-09-15T14:18:51.000000000-04:00 ee46febd64ac629f7de9cd8bf58582e6f263d97ff46896adc5b508db804682da: (from busybox) resize
2015-09-15T14:18:51.000000000-04:00 a78c9149b1c0474502a117efaa814541926c2ae6ec3c76607e1c931b84c3a44b: (from busybox) resize
```
By having a field just for Nano time, when set, the marshalling back to
`time.Unix(sec int64, nsec int64)` has zeros exactly where it needs to.
This does not break any existing use of jsonmessage.JSONMessage, but now
allows for use of `UnixNano()` and get event formatting that has
distinguishable order. Example:
```
2015-09-15T15:37:23.810295632-04:00 6adcf8ed9f5f5ec059a915466cd1cde86a18b4a085fc3af405e9cc9fecbbbbaf: (from busybox) resize
2015-09-15T15:37:23.810412202-04:00 6b7c5bfdc3f902096f5a91e628f21bd4b56e32590c5b4b97044aafc005ddcb0d: (from busybox) resize
```
Including tests for TimeNano and updated event API reference doc.
Signed-off-by: Vincent Batts <vbatts@redhat.com>
- The build-time variables are passed as environment-context for command(s)
run as part of the RUN primitve. These variables are not persisted in environment of
intermediate and final images when passed as context for RUN. The build environment
is prepended to the intermediate continer's command string for aiding cache lookups.
It also helps with build traceability. But this also makes the feature less secure from
point of view of passing build time secrets.
- The build-time variables also get used to expand the symbols used in certain
Dockerfile primitves like ADD, COPY, USER etc, without an explicit prior definiton using a
ENV primitive. These variables get persisted in the intermediate and final images
whenever they are expanded.
- The build-time variables are only expanded or passed to the RUN primtive if they
are defined in Dockerfile using the ARG primitive or belong to list of built-in variables.
HTTP_PROXY, HTTPS_PROXY, http_proxy, https_proxy, FTP_PROXY and NO_PROXY are built-in
variables that needn't be explicitly defined in Dockerfile to use this feature.
Signed-off-by: Madhav Puri <madhav.puri@gmail.com>
