NATS logging driver

Estimated reading time: 3 minutes

Docker logging driver for sending container the logs as events published to NATS in JSON format.

Usage

You can configure the default logging driver by passing the --log-driver option to the Docker daemon:

$ dockerd --log-driver=nats

You can set the logging driver for a specific container by using the --log-driver option to docker run:

$ docker run --log-driver=nats ...

This log driver does not implement a reader so it is incompatible with docker logs.

nats options

You can use the --log-opt NAME=VALUE flag to customize the logging driver for NATS:

Option	Required	Description
`labels`	optional	Comma-separated list of keys of labels, which should be included in message, if these labels are specified for container.
`env`	optional	Comma-separated list of keys of environment variables, which should be included in message, if these variables are specified for container.
`tag`	optional	Specify tag for message. Refer to the log tag option documentation for customizing the log tag format.
`nats-servers`	optional	NATS cluster nodes separated by commas. e.g. `nats://127.0.0.1:4222,nats://127.0.0.1:4223`. Defaults to `localhost:4222`
`nats-max-reconnect`	optional	Maximum attempts that the driver will try to connect before giving up. Defaults to infinite (`-1`)
`nats-subject`	optional	Specific subject to which logs will be published. Defaults to using `tag` if not specified
`nats-user`	optional	Specify user in case of authentication required
`nats-pass`	optional	Specify password in case of authentication required
`nats-token`	optional	Specify token in case of authentication required
`nats-tls-ca-cert`	optional	Specified the absolute path to the trust certificates signed by the CA
`nats-tls-cert`	optional	Specifies the absolute path to the TLS certificate file
`nats-tls-key`	optional	Specifies the absolute path to the TLS key file
`nats-tls-skip-verify`	optional	Specifies whether to skip verification by setting it to `true`

Below is an example usage of the driver for sending logs to a node in a NATS cluster to the docker.logs subject:

$ docker run --log-driver=nats \
             --log-opt nats-subject=docker.logs \
             --log-opt nats-servers=nats://nats-node-1:4222,nats://nats-node-2:4222,nats://nats-node-3:4222 \
             your/application

By default, the tag is used as the subject for NATS, so it has to be a valid subject in case subject it is left unspecified:


$ docker run --log-driver nats \
             --log-opt tag="docker.{{.ID}}.{{.ImageName}}"
             your/application

Secure connection to NATS using TLS can be customized by setting tls:// scheme in the URI and absolute paths to the certs and key files:

docker run --log-driver nats \
           --log-opt nats-tls-key=/srv/configs/certs/client-key.pem \
           --log-opt nats-tls-cert=/srv/configs/certs/client-cert.pem \
           --log-opt nats-tls-ca-cert=/srv/configs/certs/ca.pem \
           --log-opt nats-servers="tls://127.0.0.1:4223,tls://127.0.0.1:4222" \
           your/application

Skip verify is enabled by default, in order to deactivate we can specify nats-tls-skip-verify:

  docker run --log-driver nats \
             --log-opt nats-tls-skip-verify \
             --log-opt nats-servers="tls://127.0.0.1:4223,tls://127.0.0.1:4222" \
             your/application

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