---
description: Describes how to use the Google Cloud Logging driver.
keywords: gcplogs, google, docker, logging, driver
title: Google Cloud Logging driver
---

The Google Cloud Logging driver sends container logs to
[Google Cloud Logging](https://cloud.google.com/logging/docs/){: target="_blank" class="_" }
Logging.

## Usage

To use the `gcplogs` driver as the default logging driver, set the `log-driver`
and `log-opt` keys to appropriate values in the `daemon.json` file, which is
located in `/etc/docker/` on Linux hosts or
`C:\ProgramData\docker\config\daemon.json` on Windows Server. For more about
configuring Docker using `daemon.json`, see
[daemon.json](/engine/reference/commandline/dockerd.md#daemon-configuration-file).

The following example sets the log driver to `gcplogs` and sets the
`gcp-meta-name` option.

```json
{
  "log-driver": "gcplogs",
  "log-opts": {
    "gcp-meta-name": "example-instance-12345"
  }
}
```

Restart Docker for the changes to take effect.

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

    docker run --log-driver=gcplogs ...

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

If Docker detects that it is running in a Google Cloud Project, it discovers
configuration from the
[instance metadata service](https://cloud.google.com/compute/docs/metadata){: target="_blank" class="_"}.
Otherwise, the user must specify
which project to log to using the `--gcp-project` log option and Docker
attempts to obtain credentials from the
[Google Application Default Credential](https://developers.google.com/identity/protocols/application-default-credentials){: target="_blank" class="_"}.
The `--gcp-project` flag takes precedence over information discovered from the
metadata server so a Docker daemon running in a Google Cloud Project can be
overridden to log to a different Google Cloud Project using `--gcp-project`.

Docker fetches the values for zone, instance name and instance ID from Google
Cloud metadata server. Those values can be provided via options if metadata
server is not available. They do not override the values from metadata server.

## gcplogs options

You can use the `--log-opt NAME=VALUE` flag to specify these additional Google
Cloud Logging driver options:

| Option          | Required | Description                                                                                                                                                  |
|:----------------|:---------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `gcp-project`   | optional | Which GCP project to log to. Defaults to discovering this value from the GCE metadata service.                                                               |
| `gcp-log-cmd`   | optional | Whether to log the command that the container was started with. Defaults to false.                                                                           |
| `labels`        | optional | Comma-separated list of keys of labels, which should be included in message, if these labels are specified for the container.                                    |
| `env`           | optional | Comma-separated list of keys of environment variables, which should be included in message, if these variables are specified for the container.                  |
| `env-regex`     | optional | Similar to and compatible with `env`. A regular expression to match logging-related environment variables. Used for advanced [log tag options](log_tags.md). |
| `gcp-meta-zone` | optional | Zone name for the instance.                                                                                                                                  |
| `gcp-meta-name` | optional | Instance name.                                                                                                                                               |
| `gcp-meta-id`   | optional | Instance ID.                                                                                                                                                 |

If there is collision between `label` and `env` keys, the value of the `env`
takes precedence. Both options add additional fields to the attributes of a
logging message.

Below is an example of the logging options required to log to the default
logging destination which is discovered by querying the GCE metadata server.

    docker run --log-driver=gcplogs \
        --log-opt labels=location \
        --log-opt env=TEST \
        --log-opt gcp-log-cmd=true \
        --env "TEST=false" \
        --label location=west \
        your/application

This configuration also directs the driver to include in the payload the label
`location`, the environment variable `ENV`, and the command used to start the
container.

An example of the logging options for running outside of GCE (the daemon must be
configured with GOOGLE_APPLICATION_CREDENTIALS):

    docker run --log-driver=gcplogs \
        --log-opt gcp-project=test-project
        --log-opt gcp-meta-zone=west1 \
        --log-opt gcp-meta-name=`hostname` \
        your/application