From a821292ec87632eb218d936080d8ec48678c82db Mon Sep 17 00:00:00 2001 From: Nalin Dahyabhai Date: Thu, 23 Jul 2015 11:02:56 -0400 Subject: [PATCH] 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 (github: nalind) --- docs/reference/commandline/logs.md | 4 ++-- docs/reference/run.md | 4 ++-- man/docker-create.1.md | 3 ++- man/docker-logs.1.md | 3 ++- man/docker-run.1.md | 3 ++- man/docker.1.md | 3 ++- 6 files changed, 12 insertions(+), 8 deletions(-) diff --git a/docs/reference/commandline/logs.md b/docs/reference/commandline/logs.md index a2e69e4d21..49005d09db 100644 --- a/docs/reference/commandline/logs.md +++ b/docs/reference/commandline/logs.md @@ -20,8 +20,8 @@ weight=1 -t, --timestamps=false Show timestamps --tail="all" Number of lines to show from the end of the logs -NOTE: this command is available only for containers with `json-file` logging -driver. +NOTE: this command is available only for containers with `json-file` and +`journald` logging drivers. The `docker logs` command batch-retrieves logs present at the time of execution. diff --git a/docs/reference/run.md b/docs/reference/run.md index ced540d2a2..f4159114cc 100644 --- a/docs/reference/run.md +++ b/docs/reference/run.md @@ -1013,8 +1013,8 @@ container's logging driver. The following options are supported: | `fluentd` | Fluentd logging driver for Docker. Writes log messages to `fluentd` (forward input). | | `awslogs` | Amazon CloudWatch Logs logging driver for Docker. Writes log messages to Amazon CloudWatch Logs | - The `docker logs`command is available only for the `json-file` logging -driver. For detailed information on working with logging drivers, see +The `docker logs` command is available only for the `json-file` and `journald` +logging drivers. For detailed information on working with logging drivers, see [Configure a logging driver](/reference/logging/overview/). diff --git a/man/docker-create.1.md b/man/docker-create.1.md index d040e62b7b..21f411a716 100644 --- a/man/docker-create.1.md +++ b/man/docker-create.1.md @@ -171,7 +171,8 @@ millions of trillions. **--log-driver**="|*json-file*|*syslog*|*journald*|*gelf*|*fluentd*|*awslogs*|*none*" Logging driver for container. Default is defined by daemon `--log-driver` flag. - **Warning**: `docker logs` command works only for `json-file` logging driver. + **Warning**: the `docker logs` command works only for the `json-file` and + `journald` logging drivers. **--log-opt**=[] Logging driver specific options. diff --git a/man/docker-logs.1.md b/man/docker-logs.1.md index 8ecc20df24..2925c35009 100644 --- a/man/docker-logs.1.md +++ b/man/docker-logs.1.md @@ -23,7 +23,8 @@ The **docker logs --follow** command combines commands **docker logs** and **docker attach**. It will first return all logs from the beginning and then continue streaming new output from the container’s stdout and stderr. -**Warning**: This command works only for **json-file** logging driver. +**Warning**: This command works only for the **json-file** or **journald** +logging drivers. # OPTIONS **--help** diff --git a/man/docker-run.1.md b/man/docker-run.1.md index b37d07b0e9..9c7ae985de 100644 --- a/man/docker-run.1.md +++ b/man/docker-run.1.md @@ -271,7 +271,8 @@ which interface and port to use. **--log-driver**="|*json-file*|*syslog*|*journald*|*gelf*|*fluentd*|*awslogs*|*none*" Logging driver for container. Default is defined by daemon `--log-driver` flag. - **Warning**: `docker logs` command works only for `json-file` logging driver. + **Warning**: the `docker logs` command works only for the `json-file` and + `journald` logging drivers. **--log-opt**=[] Logging driver specific options. diff --git a/man/docker.1.md b/man/docker.1.md index 2d001138f2..b5b93ba4b5 100644 --- a/man/docker.1.md +++ b/man/docker.1.md @@ -121,7 +121,8 @@ unix://[/path/to/socket] to use. **--log-driver**="*json-file*|*syslog*|*journald*|*gelf*|*fluentd*|*awslogs*|*none*" Default driver for container logs. Default is `json-file`. - **Warning**: `docker logs` command works only for `json-file` logging driver. + **Warning**: the `docker logs` command works only for the `json-file` and + `journald` logging drivers. **--log-opt**=[] Logging driver specific options.