[[add-docker-metadata]]
=== Add Docker metadata

The `add_docker_metadata` processor annotates each event with relevant metadata
from Docker containers. At startup it detects a docker environment and caches the metadata.
The events are annotated with Docker metadata, only if a valid configuration
is detected and the processor is able to reach Docker API.

Each event is annotated with:

* Container ID
* Name
* Image
* Labels

[NOTE]
=====
When running {beatname_uc} in a container, you need to provide access to
Docker’s unix socket in order for the `add_docker_metadata` processor to work.
You can do this by mounting the socket inside the container. For example:

`docker run -v /var/run/docker.sock:/var/run/docker.sock ...`

To avoid privilege issues, you may also need to add `--user=root` to the
`docker run` flags. Because the user must be part of the docker group in order
to access `/var/run/docker.sock`, root access is required if {beatname_uc} is
running as non-root inside the container.
=====

[source,yaml]
-------------------------------------------------------------------------------
processors:
- add_docker_metadata:
    host: "unix:///var/run/docker.sock"
    #match_fields: ["system.process.cgroup.id"]
    #match_pids: ["process.pid", "process.ppid"]
    #match_source: true
    #match_source_index: 4
    #match_short_id: true
    #cleanup_timeout: 60
    #labels.dedot: false
    # To connect to Docker over TLS you must specify a client and CA certificate.
    #ssl:
    #  certificate_authority: "/etc/pki/root/ca.pem"
    #  certificate:           "/etc/pki/client/cert.pem"
    #  key:                   "/etc/pki/client/cert.key"
-------------------------------------------------------------------------------

It has the following settings:

`host`:: (Optional) Docker socket (UNIX or TCP socket). It uses
`unix:///var/run/docker.sock` by default.

`ssl`:: (Optional) SSL configuration to use when connecting to the Docker
socket.

`match_fields`:: (Optional) A list of fields to match a container ID, at least
one of them should hold a container ID to get the event enriched.

`match_pids`:: (Optional) A list of fields that contain process IDs. If the
process is running in Docker then the event will be enriched. The default value
is `["process.pid", "process.ppid"]`.

`match_source`:: (Optional) Match container ID from a log path present in the
`log.file.path` field. Enabled by default.

`match_short_id`:: (Optional) Match container short ID from a log path present
in the `log.file.path` field. Disabled by default.
This allows to match directories names that have the first 12 characters
of the container ID. For example, `/var/log/containers/b7e3460e2b21/*.log`.

`match_source_index`:: (Optional) Index in the source path split by `/` to look
for container ID. It defaults to 4 to match
`/var/lib/docker/containers/<container_id>/*.log`

`cleanup_timeout`:: (Optional) Time of inactivity to consider we can clean and
forget metadata for a container, 60s by default.

`labels.dedot`:: (Optional) Default to be false. If set to true, replace dots in
 labels with `_`.
