Commit graph

79 commits

Author SHA1 Message Date
Sebastiaan van Stijn
5e2a1195d7
swap logrus types for their containerd/logs aliases
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2023-08-01 13:02:55 +02:00
Brian Goff
74da6a6363 Switch all logging to use containerd log pkg
This unifies our logging and allows us to propagate logging and trace
contexts together.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2023-06-24 00:23:44 +00:00
Cory Snider
0b592467d9 daemon: read-copy-update the daemon config
Ensure data-race-free access to the daemon configuration without
locking by mutating a deep copy of the config and atomically storing
a pointer to the copy into the daemon-wide configStore value. Any
operations which need to read from the daemon config must capture the
configStore value only once and pass it around to guarantee a consistent
view of the config.

Signed-off-by: Cory Snider <csnider@mirantis.com>
2023-06-01 14:45:24 -04:00
cui fliter
f66684fdeb fix some comments
Signed-off-by: cui fliter <imcusg@gmail.com>
2023-04-25 13:39:28 +08:00
Sebastiaan van Stijn
eb14d936bf
daemon: rename variables that collide with imported package names
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2020-04-14 17:22:23 +02:00
Brian Goff
750f0d1648 Support configuration of log cacher.
Configuration over the API per container is intentionally left out for
the time being, but is supported to configure the default from the
daemon config.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit cbecf48bc352e680a5390a7ca9cff53098cd16d7)
Signed-off-by: Madhu Venugopal <madhu@docker.com>
2020-02-19 17:02:34 -05:00
Kir Kolyshkin
916eabd459 daemon.ContainerLogs(): fix resource leak on follow
When daemon.ContainerLogs() is called with options.follow=true
(as in "docker logs --follow"), the "loggerutils.followLogs()"
function never returns (even then the logs consumer is gone).
As a result, all the resources associated with it (including
an opened file descriptor for the log file being read, two FDs
for a pipe, and two FDs for inotify watch) are never released.

If this is repeated (such as by running "docker logs --follow"
and pressing Ctrl-C a few times), this results in DoS caused by
either hitting the limit of inotify watches, or the limit of
opened files. The only cure is daemon restart.

Apparently, what happens is:

1. logs producer (a container) is gone, calling (*LogWatcher).Close()
for all its readers (daemon/logger/jsonfilelog/jsonfilelog.go:175).

2. WatchClose() is properly handled by a dedicated goroutine in
followLogs(), cancelling the context.

3. Upon receiving the ctx.Done(), the code in followLogs()
(daemon/logger/loggerutils/logfile.go#L626-L638) keeps to
send messages _synchronously_ (which is OK for now).

4. Logs consumer is gone (Ctrl-C is pressed on a terminal running
"docker logs --follow"). Method (*LogWatcher).Close() is properly
called (see daemon/logs.go:114). Since it was called before and
due to to once.Do(), nothing happens (which is kinda good, as
otherwise it will panic on closing a closed channel).

5. A goroutine (see item 3 above) keeps sending log messages
synchronously to the logWatcher.Msg channel. Since the
channel reader is gone, the channel send operation blocks forever,
and resource cleanup set up in defer statements at the beginning
of followLogs() never happens.

Alas, the fix is somewhat complicated:

1. Distinguish between close from logs producer and logs consumer.
To that effect,
 - yet another channel is added to LogWatcher();
 - {Watch,}Close() are renamed to {Watch,}ProducerGone();
 - {Watch,}ConsumerGone() are added;

*NOTE* that ProducerGone()/WatchProducerGone() pair is ONLY needed
in order to stop ConsumerLogs(follow=true) when a container is stopped;
otherwise we're not interested in it. In other words, we're only
using it in followLogs().

2. Code that was doing (logWatcher*).Close() is modified to either call
ProducerGone() or ConsumerGone(), depending on the context.

3. Code that was waiting for WatchClose() is modified to wait for
either ConsumerGone() or ProducerGone(), or both, depending on the
context.

4. followLogs() are modified accordingly:
 - context cancellation is happening on WatchProducerGone(),
and once it's received the FileWatcher is closed and waitRead()
returns errDone on EOF (i.e. log rotation handling logic is disabled);
 - due to this, code that was writing synchronously to logWatcher.Msg
can be and is removed as the code above it handles this case;
 - function returns once ConsumerGone is received, freeing all the
resources -- this is the bugfix itself.

While at it,

1. Let's also remove the ctx usage to simplify the code a bit.
It was introduced by commit a69a59ffc7 ("Decouple removing the
fileWatcher from reading") in order to fix a bug. The bug was actually
a deadlock in fsnotify, and the fix was just a workaround. Since then
the fsnofify bug has been fixed, and a new fsnotify was vendored in.
For more details, please see
https://github.com/moby/moby/pull/27782#issuecomment-416794490

2. Since `(*filePoller).Close()` is fixed to remove all the files
being watched, there is no need to explicitly call
fileWatcher.Remove(name) anymore, so get rid of the extra code.

Should fix https://github.com/moby/moby/issues/37391

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
2018-09-06 11:47:42 -07:00
Kir Kolyshkin
2e4c2a6bf9 daemon.ContainerLogs: minor debug logging cleanup
This code has many return statements, for some of them the
"end logs" or "end stream" message was not printed, giving
the impression that this "for" loop never ended.

Make sure that "begin logs" is to be followed by "end logs".

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
2018-09-06 11:45:50 -07:00
Brian Goff
2c252a48c2 Fix race conditions in logs API
Closing the log driver was in a defer meanwhile logs are
collected asyncronously, so the log driver was being closed before reads
were actually finished.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2018-05-14 15:48:32 -04:00
Kir Kolyshkin
7d62e40f7e Switch from x/net/context -> context
Since Go 1.7, context is a standard package. Since Go 1.9, everything
that is provided by "x/net/context" is a couple of type aliases to
types in "context".

Many vendored packages still use x/net/context, so vendor entry remains
for now.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
2018-04-23 13:52:44 -07:00
Brian Goff
b0b9a25e7e Move log validator logic after plugins are loaded
This ensures that all log plugins are registered when the log validator
is run.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2018-02-15 11:53:11 -05:00
Daniel Nephin
4f0d95fa6e Add canonical import comment
Signed-off-by: Daniel Nephin <dnephin@docker.com>
2018-02-05 16:51:57 -05:00
Brian Goff
d453fe35b9 Move api/errdefs to errdefs
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2018-01-11 21:21:43 -05:00
Brian Goff
87a12421a9 Add helpers to create errdef errors
Instead of having to create a bunch of custom error types that are doing
nothing but wrapping another error in sub-packages, use a common helper
to create errors of the requested type.

e.g. instead of re-implementing this over and over:

```go
type notFoundError struct {
  cause error
}

func(e notFoundError) Error() string {
  return e.cause.Error()
}

func(e notFoundError) NotFound() {}

func(e notFoundError) Cause() error {
  return e.cause
}
```

Packages can instead just do:

```
  errdefs.NotFound(err)
```

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2018-01-11 21:21:43 -05:00
Brian Goff
16f7cd6749 Move json log reading into log file object
This allows much of the read logic to be shared for other things,
especially for the new log driver proposed in
https://github.com/moby/moby/issues/33475

The only logic for reads in the json logger is around decoding log
messages, which gets passed into the log file object.

This also helps with implementing compression as it allows us to
simplify locking strategies.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2017-11-04 08:31:58 -04:00
Jamie Hannaford
e8d9a61f4c Add --until flag for docker logs; closes #32807
Signed-off-by: Jamie Hannaford <jamie.hannaford@rackspace.com>
2017-11-01 10:08:49 +01:00
Brian Goff
ebcb7d6b40 Remove string checking in API error handling
Use strongly typed errors to set HTTP status codes.
Error interfaces are defined in the api/errors package and errors
returned from controllers are checked against these interfaces.

Errors can be wraeped in a pkg/errors.Causer, as long as somewhere in the
line of causes one of the interfaces is implemented. The special error
interfaces take precedence over Causer, meaning if both Causer and one
of the new error interfaces are implemented, the Causer is not
traversed.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2017-08-15 16:01:11 -04:00
Derek McGowan
1009e6a40b
Update logrus to v1.0.1
Fixes case sensitivity issue

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
2017-07-31 13:16:46 -07:00
Jim Minter
4fdb17c777 Prevent ContainerLogs from hanging if container doesn't run for long
Signed-off-by: Jim Minter <jminter@redhat.com>
2017-04-20 12:27:51 +01:00
Jim Minter
68e71aa3e6 Close logger only after StartLogger call
Signed-off-by: Jim Minter <jminter@redhat.com>
2017-04-20 12:27:50 +01:00
Drew Erny
1044093bb0 refactor logs and support service logs /w tty
Refactor container logs system to make communicating log messages
internally much simpler. Move responsibility for marshalling log
messages into the REST server. Support TTY logs. Pave the way for fixing
the ambiguous bytestream format. Pave the way for fixing details.

Signed-off-by: Drew Erny <drew.erny@docker.com>
2017-04-06 17:54:11 -07:00
Lei Jitang
238ad8c36a Fix docker logs a dead container
If a container is dead or marked for removal, the json log
file could have been removed, so docker logs will return
`<id>-json.log: no such file or directory`.

Signed-off-by: Lei Jitang <leijitang@huawei.com>
2017-03-24 21:20:52 -04:00
Kenfe-Mickael Laventure
fb2bb3653e Close logwatcher on context cancellation
This commit addresses 2 issues:

  1. in `tailfile()` if somehow the `logWatcher.Msg` were to become full and the watcher closed before space was made into it, we were getting stuck there forever since we were not checking for the watcher getting closed
  2. when servicing `docker logs`, if the command was cancelled we were not closing the watcher (and hence notifying it to stop copying data)

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
2017-01-17 14:36:13 -08:00
Ke Li
514adcf458 Remove redundant format
Signed-off-by: Ke Li <kel@splunk.com>

Add missing changes

Signed-off-by: Ke Li <kel@splunk.com>

User errors.New to create error

Signed-off-by: Ke Li <kel@splunk.com>
2016-12-27 21:46:52 +08:00
Sebastiaan van Stijn
05dc9846e1
remove client-side for supported logging drivers
The `docker logs` command performed a
client-side check if the container's
logging driver was supported.

Now that we allow the client to connect
to both "older" and "newer" daemon versions,
this check is best done daemon-side.

This patch remove the check on the client
side, and leaves validation to the daemon,
which should be the source of truth.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2016-12-19 14:30:01 +01:00
Yanqiang Miao
58028a2919 Eliminate redundant parameters
Signed-off-by: Yanqiang Miao <miao.yanqiang@zte.com.cn>

update

Signed-off-by: Yanqiang Miao <miao.yanqiang@zte.com.cn>
2016-11-23 09:28:13 +08:00
Tonis Tiigi
37a3be2449 Move stdio attach from libcontainerd backend to callback
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
2016-10-24 00:20:36 -07:00
Michael Crosby
7c36a1af03 Move engine-api client package
This moves the engine-api client package to `/docker/docker/client`.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
2016-09-07 11:05:58 -07:00
Michael Crosby
91e197d614 Add engine-api types to docker
This moves the types for the `engine-api` repo to the existing types
package.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
2016-09-07 11:05:58 -07:00
Brian Goff
7dff310648 Fix panic while merging log configs to nil map
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-07-12 15:24:42 -04:00
Stefan J. Wernli
54f11b84d2 Fixing file handle leak for "docker logs"
If "docker logs" was used on an offline container, the logger is leaked, leaving it up to the finalizer to close the file handle, which could block removal of the container.  Further, the json file logger could leak an open handle if the logs are read without follow due to an early return without a close.  This change addresses both cases.

Signed-off-by: Stefan J. Wernli <swernli@microsoft.com>
2016-06-21 18:40:30 -07:00
Yong Tang
a72b45dbec Fix logrus formatting
This fix tries to fix logrus formatting by removing `f` from
`logrus.[Error|Warn|Debug|Fatal|Panic|Info]f` when formatting string
is not present.

This fix fixes #23459.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
2016-06-11 13:16:55 -07:00
Nalin Dahyabhai
7772d270c0 Remove the logger.Message ContainerID field
Log drivers are instantiated on a per-container basis, and passed the
container ID (along with other information) when they're initialized.
Drivers that care about that value are caching the value that they're
passed when they're initialized and using it in favor of the value
contained in Message structures that are passed to them, so the field in
Messages is unused, so we remove it.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>
2016-05-31 16:41:29 -04:00
Brian Goff
bd9d14a07b Add support for reading logs extra attrs
The jsonlog logger currently allows specifying envs and labels that
should be propagated to the log message, however there has been no way
to read that back.

This adds a new API option to enable inserting these attrs back to the
log reader.

With timestamps, this looks like so:
```
92016-04-08T15:28:09.835913720Z foo=bar,hello=world hello
```

The extra attrs are comma separated before the log message but after
timestamps.

Without timestaps it looks like so:
```
foo=bar,hello=world hello
```

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-05-06 20:42:20 -04:00
Shijiang Wei
1790980ec6 inherit the daemon log options when creating containers
Signed-off-by: Shijiang Wei <mountkin@gmail.com>
2016-05-02 23:04:04 +08:00
Alexander Morozov
62c9e62edc use router.Cancellable instead of direct CloseNotify
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
2016-03-25 11:33:54 -07:00
Stefan J. Wernli
4570cfd3ba Fixing logs file handle leak.
Docker logs was only closing the logger when the HTTP response writer received a close notification, however in non-follow mode the writer never receives a close. This means that the daemon would leak the file handle to the log, preventing the container from being removed on Windows (file in use error). This change explicitly closes the log when the end of stream is hit.

Signed-off-by: Stefan J. Wernli <swernli@microsoft.com>
2016-03-18 11:00:15 -07:00
Shijiang Wei
068085005e validate log-opt when creating containers AGAIN
Signed-off-by: Shijiang Wei <mountkin@gmail.com>
2016-03-02 20:30:26 +08:00
David Calavera
a793564b25 Remove static errors from errors package.
Moving all strings to the errors package wasn't a good idea after all.

Our custom implementation of Go errors predates everything that's nice
and good about working with errors in Go. Take as an example what we
have to do to get an error message:

```go
func GetErrorMessage(err error) string {
	switch err.(type) {
	case errcode.Error:
		e, _ := err.(errcode.Error)
		return e.Message

	case errcode.ErrorCode:
		ec, _ := err.(errcode.ErrorCode)
		return ec.Message()

	default:
		return err.Error()
	}
}
```

This goes against every good practice for Go development. The language already provides a simple, intuitive and standard way to get error messages, that is calling the `Error()` method from an error. Reinventing the error interface is a mistake.

Our custom implementation also makes very hard to reason about errors, another nice thing about Go. I found several (>10) error declarations that we don't use anywhere. This is a clear sign about how little we know about the errors we return. I also found several error usages where the number of arguments was different than the parameters declared in the error, another clear example of how difficult is to reason about errors.

Moreover, our custom implementation didn't really make easier for people to return custom HTTP status code depending on the errors. Again, it's hard to reason about when to set custom codes and how. Take an example what we have to do to extract the message and status code from an error before returning a response from the API:

```go
	switch err.(type) {
	case errcode.ErrorCode:
		daError, _ := err.(errcode.ErrorCode)
		statusCode = daError.Descriptor().HTTPStatusCode
		errMsg = daError.Message()

	case errcode.Error:
		// For reference, if you're looking for a particular error
		// then you can do something like :
		//   import ( derr "github.com/docker/docker/errors" )
		//   if daError.ErrorCode() == derr.ErrorCodeNoSuchContainer { ... }

		daError, _ := err.(errcode.Error)
		statusCode = daError.ErrorCode().Descriptor().HTTPStatusCode
		errMsg = daError.Message

	default:
		// This part of will be removed once we've
		// converted everything over to use the errcode package

		// FIXME: this is brittle and should not be necessary.
		// If we need to differentiate between different possible error types,
		// we should create appropriate error types with clearly defined meaning
		errStr := strings.ToLower(err.Error())
		for keyword, status := range map[string]int{
			"not found":             http.StatusNotFound,
			"no such":               http.StatusNotFound,
			"bad parameter":         http.StatusBadRequest,
			"conflict":              http.StatusConflict,
			"impossible":            http.StatusNotAcceptable,
			"wrong login/password":  http.StatusUnauthorized,
			"hasn't been activated": http.StatusForbidden,
		} {
			if strings.Contains(errStr, keyword) {
				statusCode = status
				break
			}
		}
	}
```

You can notice two things in that code:

1. We have to explain how errors work, because our implementation goes against how easy to use Go errors are.
2. At no moment we arrived to remove that `switch` statement that was the original reason to use our custom implementation.

This change removes all our status errors from the errors package and puts them back in their specific contexts.
IT puts the messages back with their contexts. That way, we know right away when errors used and how to generate their messages.
It uses custom interfaces to reason about errors. Errors that need to response with a custom status code MUST implementent this simple interface:

```go
type errorWithStatus interface {
	HTTPErrorStatusCode() int
}
```

This interface is very straightforward to implement. It also preserves Go errors real behavior, getting the message is as simple as using the `Error()` method.

I included helper functions to generate errors that use custom status code in `errors/errors.go`.

By doing this, we remove the hard dependency we have eeverywhere to our custom errors package. Yes, you can use it as a helper to generate error, but it's still very easy to generate errors without it.

Please, read this fantastic blog post about errors in Go: http://dave.cheney.net/2014/12/24/inspecting-errors

Signed-off-by: David Calavera <david.calavera@gmail.com>
2016-02-26 15:49:09 -05:00
Brian Goff
ae4ee974e8 Move stream flushes to backend
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-02-09 14:25:02 -05:00
David Calavera
06d8f504f7 Move backend types to their own package.
- Remove duplicated structs that we already have in engine-api.

Signed-off-by: David Calavera <david.calavera@gmail.com>
2016-02-08 12:42:17 -05:00
Lukas Waslowski
dd93571c69 Decouple the "container" router from the actual daemon implementation.
This is done by moving the following types to api/types/config.go:
  - ContainersConfig
  - ContainerAttachWithLogsConfig
  - ContainerWsAttachWithLogsConfig
  - ContainerLogsConfig
  - ContainerStatsConfig

Remove dependency on "version" package from types.ContainerStatsConfig.
Decouple the "container" router from the "daemon/exec" implementation.

* This is done by making daemon.ContainerExecInspect() return an interface{}
value. The same trick is already used by daemon.ContainerInspect().

Improve documentation for router packages.
Extract localRoute and router into separate files.
Move local.router to image.imageRouter.

Changes:
  - Move local/image.go to image/image_routes.go.
  - Move local/local.go to image/image.go
  - Rename router to imageRouter.
  - Simplify imports for image/image.go (remove alias for router package).

Merge router/local package into router package.
Decouple the "image" router from the actual daemon implementation.
Add Daemon.GetNetworkByID and Daemon.GetNetworkByName.
Decouple the "network" router from the actual daemon implementation.

This is done by replacing the daemon.NetworkByName constant with
an explicit GetNetworkByName method.

Remove the unused Daemon.GetNetwork method and the associated constants NetworkByID and NetworkByName.

Signed-off-by: Lukas Waslowski <cr7pt0gr4ph7@gmail.com>
Signed-off-by: David Calavera <david.calavera@gmail.com>
2016-02-08 11:30:57 -05:00
David Calavera
d7d512bb92 Rename Daemon.Get to Daemon.GetContainer.
This is more aligned with `Daemon.GetImage` and less confusing.

Signed-off-by: David Calavera <david.calavera@gmail.com>
2015-12-11 12:39:28 -05:00
David Calavera
6bb0d1816a Move Container to its own package.
So other packages don't need to import the daemon package when they
want to use this struct.

Signed-off-by: David Calavera <david.calavera@gmail.com>
Signed-off-by: Tibor Vass <tibor@docker.com>
2015-12-03 17:39:49 +01:00
David Calavera
c412300dd9 Decouple daemon and container to configure logging drivers.
Signed-off-by: David Calavera <david.calavera@gmail.com>
2015-11-04 12:27:49 -05:00
Morgan Bauer
1eecc1e7e5
refactor logs to not use internal data structures
- refactor to make it easier to split the api in the future
 - additional tests for non existent container case

Signed-off-by: Morgan Bauer <mbauer@us.ibm.com>
2015-10-07 15:44:16 -07:00
Tibor Vass
b08f071e18 Revert "Merge pull request #16228 from duglin/ContextualizeEvents"
Although having a request ID available throughout the codebase is very
valuable, the impact of requiring a Context as an argument to every
function in the codepath of an API request, is too significant and was
not properly understood at the time of the review.

Furthermore, mixing API-layer code with non-API-layer code makes the
latter usable only by API-layer code (one that has a notion of Context).

This reverts commit de41640435, reversing
changes made to 7daeecd42d.

Signed-off-by: Tibor Vass <tibor@docker.com>

Conflicts:
	api/server/container.go
	builder/internals.go
	daemon/container_unix.go
	daemon/create.go
2015-09-29 14:26:51 -04:00
Doug Davis
26b1064967 Add context.RequestID to event stream
This PR adds a "request ID" to each event generated, the 'docker events'
stream now looks like this:

```
2015-09-10T15:02:50.000000000-07:00 [reqid: c01e3534ddca] de7c5d4ca927253cf4e978ee9c4545161e406e9b5a14617efb52c658b249174a: (from ubuntu) create
```
Note the `[reqID: c01e3534ddca]` part, that's new.

Each HTTP request will generate its own unique ID. So, if you do a
`docker build` you'll see a series of events all with the same reqID.
This allow for log processing tools to determine which events are all related
to the same http request.

I didn't propigate the context to all possible funcs in the daemon,
I decided to just do the ones that needed it in order to get the reqID
into the events. I'd like to have people review this direction first, and
if we're ok with it then I'll make sure we're consistent about when
we pass around the context - IOW, make sure that all funcs at the same level
have a context passed in even if they don't call the log funcs - this will
ensure we're consistent w/o passing it around for all calls unnecessarily.

ping @icecrime @calavera @crosbymichael

Signed-off-by: Doug Davis <dug@us.ibm.com>
2015-09-24 11:56:37 -07:00
Doug Davis
0a734182eb Move more 'daemon' errors to the new error package
Signed-off-by: Doug Davis <dug@us.ibm.com>
2015-09-23 09:51:45 -07:00
Nalin Dahyabhai
e611a189cb Add log reading to the journald log driver
If a logdriver doesn't register a callback function to validate log
options, it won't be usable.  Fix the journald driver by adding a dummy
validator.

Teach the client and the daemon's "logs" logic that the server can also
supply "logs" data via the "journald" driver.  Update documentation and
tests that depend on error messages.

Add support for reading log data from the systemd journal to the
journald log driver.  The internal logic uses a goroutine to scan the
journal for matching entries after any specified cutoff time, formats
the messages from those entries as JSONLog messages, and stuffs the
results down a pipe whose reading end we hand back to the caller.

If we are missing any of the 'linux', 'cgo', or 'journald' build tags,
however, we don't implement a reader, so the 'logs' endpoint will still
return an error.

Make the necessary changes to the build setup to ensure that support for
reading container logs from the systemd journal is built.

Rename the Jmap member of the journald logdriver's struct to "vars" to
make it non-public, and to make it easier to tell that it's just there
to hold additional variable values that we want journald to record along
with log data that we're sending to it.

In the client, don't assume that we know which logdrivers the server
implements, and remove the check that looks at the server.  It's
redundant because the server already knows, and the check also makes
using older clients with newer servers (which may have new logdrivers in
them) unnecessarily hard.

When we try to "logs" and have to report that the container's logdriver
doesn't support reading, send the error message through the
might-be-a-multiplexer so that clients which are expecting multiplexed
data will be able to properly display the error, instead of tripping
over the data and printing a less helpful "Unrecognized input header"
error.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com> (github: nalind)
2015-09-11 16:50:03 -04:00