Add docs for label/env log-opts

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

docs/reference/logging/fluentd.md

@@ -73,6 +73,24 @@ Refer to the [log tag option documentation](log_tags.md) for customizing
 the log tag format.
 
 
+### labels and env
+
+The `labels` and `env` options takes a comma-separated list of keys. If there is collision between `label` and `env` keys, the value of the `env` takes precedence.
+
+To use attributes, specify them when you start the Docker daemon.
+
+```
+docker daemon --log-driver=fluentd --log-opt labels=foo --log-opt env=foo,fizz
+```
+
+Then, run a container and specify values for the `labels` or `env`.  For example, you might use this:
+
+```
+docker run --label foo=bar -e fizz=buzz -d -P training/webapp python app.py
+````
+
+This adds additional fields to the extra attributes of a logging message.
+
 ## Fluentd daemon management with Docker
 
 About `Fluentd` itself, see [the project webpage](http://www.fluentd.org)

docs/reference/logging/journald.md

@@ -36,6 +36,31 @@ You can set the logging driver for a specific container by using the
 
     docker run --log-driver=journald ...
 
+## Options
+
+Users can use the `--log-opt NAME=VALUE` flag to specify additional
+journald logging driver options.
+
+### labels and env
+
+The `labels` and `env` options takes a comma-separated list of keys. If there is collision between `label` and `env` keys, the value of the `env` takes precedence.
+
+To use attributes, specify them when you start the Docker daemon.
+
+```
+docker daemon --log-driver=journald --log-opt labels=foo --log-opt env=foo,fizz
+```
+
+Then, run a container and specify values for the `labels` or `env`.  For example, you might use this:
+
+```
+docker run --label foo=bar -e fizz=buzz -d -P training/webapp python app.py
+````
+
+This adds additional metadata in the journal with each message, one
+for each key that matches.
+
+
 ## Note regarding container names
 
 The value logged in the `CONTAINER_NAME` field is the container name

docs/reference/logging/overview.md

@@ -27,12 +27,15 @@ container's logging driver. The following options are supported:
 
 The `docker logs`command is available only for the `json-file` logging driver.
 
+
 ## json-file options
 
 The following logging options are supported for the `json-file` logging driver:
 
     --log-opt max-size=[0-9+][k|m|g]
     --log-opt max-file=[0-9+]
+    --log-opt labels=label1,label2
+    --log-opt env=env1,env2
 
 Logs that reach `max-size` are rolled over. You can set the size in kilobytes(k), megabytes(m), or gigabytes(g). eg `--log-opt max-size=50m`. If `max-size` is not set, then logs are not rolled over.
 
@@ -41,6 +44,26 @@ Logs that reach `max-size` are rolled over. You can set the size in kilobytes(k)
 
 If `max-size` and `max-file` are set, `docker logs` only returns the log lines from the newest log file.
 
+The `labels` and `env` options add additional attributes for use with logging drivers that accept them. Each of these options takes a comma-separated list of keys. If there is collision between `label` and `env` keys, the value of the `env` takes precedence.
+
+To use attributes, specify them when you start the Docker daemon.
+
+```
+docker daemon --log-driver=json-file --log-opt labels=foo --log-opt env=foo,fizz
+```
+
+Then, run a container and specify values for the `labels` or `env`.  For example, you might use this:
+
+```
+docker run --label foo=bar -e fizz=buzz -d -P training/webapp python app.py
+````
+
+This adds additional fields depending on the driver, e.g. for
+`json-file` that looks like:
+
+    "attrs":{"fizz":"buzz","foo":"bar"}
+
+
 ## syslog options
 
 The following logging options are supported for the `syslog` logging driver:
@@ -100,6 +123,8 @@ The GELF logging driver supports the following options:
 
     --log-opt gelf-address=udp://host:port
     --log-opt tag="database"
+    --log-opt labels=label1,label2
+    --log-opt env=env1,env2
 
 The `gelf-address` option specifies the remote GELF server address that the
 driver connects to. Currently, only `udp` is supported as the transport and you must
@@ -112,6 +137,15 @@ By default, Docker uses the first 12 characters of the container ID to tag log m
 Refer to the [log tag option documentation](log_tags.md) for customizing
 the log tag format.
 
+The `labels` and `env` options are supported by the gelf logging
+driver. It adds additional key on the `extra` fields, prefixed by an
+underscore (`_`).
+
+    // […]
+    "_foo": "bar",
+    "_fizz": "buzz",
+    // […]
+
 
 ## fluentd options
 
@@ -128,6 +162,7 @@ If container cannot connect to the Fluentd daemon on the specified address,
 the container stops immediately. For detailed information on working with this
 logging driver, see [the fluentd logging driver](fluentd.md)
 
+
 ## Specify Amazon CloudWatch Logs options
 
 The Amazon CloudWatch Logs logging driver supports the following options: