Environment variables

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You can use environment variables to manage the configuration. Environment variables override settings in config.json. If a change to a setting in config.json requires a restart for it to take effect, then changes to the corresponding environment variable also require a server restart.

The name of the environment variable for any setting can be derived from the name of that setting in config.json. For example, to derive the name of the Site URL setting:

  1. Find the setting in config.json. In this case, ServiceSettings.SiteURL.

  2. Add MM_ to the beginning and convert all characters to uppercase and replace the . with _. For example, MM_SERVICESETTINGS_SITEURL.

  3. The setting becomes export MM_SERVICESETTINGS_SITEURL="http://example.com".

Note

  • If Mattermost is run from an initialization file, environment variables can be set via Environment=<>, or EnvironmentFile=<path/to/file>. In the second case, the file specified contains the list of environment variables to set.

  • When settings are configured through an environment variable, System Admins can’t modify them in the System Console. If a setting is configured through an environment variable, and any other changes are made in the System Console, the value stored of the environment variable will be written back to the config.json as that setting’s value.

  • For any setting that’s not set in config.json or in environment variables, the Mattermost server uses the setting’s default value as documented in the sections below on this page.

Warning

  • Environment variables for Mattermost settings that are set within the active shell will take effect when migrating configuration. For more information, see Configuration In Database.

  • Database connection strings for the database read and search replicas need to be formatted using URL encoding. Incorrectly formatted strings may cause some characters to terminate the string early, resulting in issues when the connection string is parsed.

Override Mattermost license file

Starting from Mattermost v5.26, you can use an environment variable to override any license in the database or file configuration without replacing those licenses.

When starting the server, specify the license key as MM_LICENSE with the contents of a license file.

Note

If MM_LICENSE is set to a non-empty string, but the license specified is not valid, the Mattermost server will be started without a license.

In a High Availability deployment, using an environment variable to override a server license only affects the individual app server and doesn’t propagate to other servers in the cluster.

Load custom configuration defaults

Starting from Mattermost v5.30, you can load a set of custom configuration defaults using an environment variable. This custom configuration applies only if the values are not already present in the current server configuration.

  1. Create a JSON file that contains the custom configuration defaults. For example, custom.json.

  2. When starting the server, point the custom defaults environment variable to the defaults file: MM_CUSTOM_DEFAULTS_PATH=custom.json.