Managing Hasura metadata

If your Postgres schema is already managed with a tool like knex, TypeORM, Django/Rails migrations, you will still need a way to export the actions you performed on the Hasura console to apply it later on another Hasura instance.

All the actions performed on the console, like tracking tables/views/functions, creating relationships, configuring permissions, creating event triggers and remote schemas, etc. can be exported as a JSON file which can be version controlled. The content of this JSON file is called “Hasura metadata”. The metadata file can be later imported to another Hasura instance to get the same configuration. You can also manually edit the JSON file to add more objects to it and then use it to update the instance.

Exporting Hasura metadata

  1. Click on the settings (⚙) icon at the top right corner of the console screen.
  2. In the Hasura metadata actions page that opens, click on the Export Metadata button.
  3. This will prompt a file download for metadata.json. Save the file.

The export can be done via the Metadata API. Response will be a JSON object with the Hasura metadata. Here is an example using curl to save this as a file:

curl -d'{"type": "export_metadata", "args": {}}' http://localhost:8080/v1/query -o metadata.json

This command will create a metadata.json file. If an admin secret is set, add -H 'X-Hasura-Admin-Secret: <your-admin-secret>' as the API is an admin-only API.

Importing Hasura metadata

You can apply exported metadata from one Hasura GraphQL engine instance to another. You can also apply an older or modified version of an instance’s metadata onto itself.

Importing completely replaces the metadata on that instance, i.e. you lose any metadata that was already present before.

  1. Click on the settings (⚙) icon at the top right corner of the console screen.
  2. Click on Import Metadata button.
  3. Choose a metadata.json file that was exported earlier.
  4. A notification should appear indicating the success or error.

The exported JSON can be imported via the Metadata API. Here is an example using curl:

curl -d'{"type":"replace_metadata", "args":'$(cat metadata.json)'}' http://localhost:8080/v1/query

This command reads the metadata.json file and makes a POST request to replace the metadata. If an admin secret is set, add -H 'X-Hasura-Admin-Secret: <your-admin-secret>' as the API is an admin-only API.

Note

All the dependent objects, like tables, views, functions etc. should exist on Postgres before importing the metadata. Otherwise, it will result in an error saying the object does not exist. So, apply the Postgres schema first, before importing the metadata.

Reloading Hasura metadata

In some cases, the metadata can be out of sync with the Postgres schema. For example, when a new column has been added to a table via an external tool such as psql.

  1. Click on the settings (⚙) icon at the top right corner of the console screen.
  2. Click on Reload button.
  3. A notification should appear indicating the success.

The reload of metadata can be done via the Metadata API. Here is an example using curl:

curl -d'{"type": "reload_metadata", "args": {}}' http://localhost:8080/v1/query

If an admin secret is set, add -H 'X-Hasura-Admin-Secret: <your-admin-secret>' as the API is an admin-only API.

Note

Reloading may result in inconsistent metadata status. You may need to resolve all inconsistent objects manually or delete them. After that, you need to reload metadata again.

Managing Hasura metadata in CI/CD

Using tools like curl you can easily integrate the metadata API requests for the above metadata management actions with your CI/CD workflows.

In case you need an automated way of applying/importing the metadata, take a look at the CLI-Migrations Docker image, which can start the GraphQL engine after automatically importing a mounted metadata file.