Authentication with the API

By default, the GraphQL API in Decidim is publically available for read-only operations and it can also be used by external applications to read data from Decidim. If you want to write data over the API, i.e. perform GraphQL mutations, you need first need to authenticate the API user to perform these operations. Otherwise, it is not possible to perform such operations as most such operations are performed as an actual user in Decidim.

More information regarding implementing the API authentication is available in the API documentation of your Decidim instance.

Signing in to the API

In case you want to use the API as a sign in user to perform mutations representing a user in Decidim, you have two available options for such integrations through the system administration panel:

Creating an OAuth application and implementing the OAuth authentication flow for the users of your application. Use this option for participant-facing applications where the participants represent themselves in Decidim through the API.
Creating API credentials and signing in to the API with these credentials to perform the operations as a signed in machine user. Use this option for machine-to-machine automations where there is no real end user interacting with Decidim.

If you only want to test the GraphQL queries as a signed in user, you can use the normal Decidim authentication functionality to sign in and then use the GraphiQL IDE to perform these queries as a signed in user.

OAuth flow for participant-facing applications

Participant-facing applications where the participants need to interact with Decidim through GraphQL mutations can be integrated using OAuth applications. In order to configure such integration capability from the system administration panel, create a new OAuth application and provide the necessary details for your integration. Note that the "application type" for such applications would typically be "Public". For more information regarding the application types, refer to RFC 6749 Section 2.1. (OAuth client types).

In order to use the OAuth access tokens to represent the user through the API, please select the following scopes as "Available" scopes for the application:

user - Authenticated users have the ability to represent a logged in user in Decidim
api:read - Authenticated users have the ability to read data from the API
api:write - Authenticated users have the ability to write data through the API (in case your external application needs to perform mutations over the API on behalf of the user)

Once configured, you can now use any OAuth authentication library to perform the OAuth authentication flow with your application users and receive an access token to utilize the Decidim API representing the signed in user. Please note that with public OAuth clients especially (and recommended also for confidential clients), you have to use PKCE with the authorization flow.

Once the OAuth application is created, you can authenticate against it with the following steps:

Send the user to perform an OAuth authorization request at Decidim with the required API scopes (user, api:read and api:write if you want to perform mutations over the API). Along with the authorization request, also send the additional parameters required by PKCE (code_challenge and code_challenge_method).
Receive an OAuth authorization code back to your application’s configured redirect URI.
Utilizing the received authorization code, request an OAuth access token from the OAuth token endpoint. Along with the token request, also send the additional parameter required by PKCE code_verifier.
The issued token is a JSON Web Token (JWT) when the authorization request contains the defined scopes. This token can be now used to represent the user in further calls to the API by passing the token with its type (Bearer) within the HTTP Authorization header with the request to the API.

When doing the requests to the API, you also need to pass the OAuth client ID within the X-Jwt-Aud header of the requests in order for the token to be recognized as a valid token for the issued client. Passing the bearer token to the Authorization header and the OAuth client ID to the X-Jwt-Aud header, you can send the following HTTP request to the API to validate that the token works and the user is recognized as signed in:

POST /api HTTP/1.1
Accept: application/json
Authorization: Bearer token
Content-Length: 53
Content-Type: application/json
Host: DOMAIN
X-Jwt-Aud: OAUTH_CLIENT_ID

{"query":"{ session { user { id name nickname } } }"}

You should see the user details in the response in case the token is valid and you have configured the API correctly. If the response does not contain the user details, please refer to the Decidim configuration documentation.

Once the interaction with the API is completed, it is recommended to revoke the tokens, which is similar to the user signing out of the application. This can be done utilizing the OAuth revocation endpoint provided by Decidim. After the token is revoked, it is no longer valid and the user has to perform a re-authorization the next time they want to utilize the API.

In case you need tokens with a longer life span, you can either look into the Decidim documentation to extend the validity period of the access tokens or enable refresh tokens for the OAuth application when configuring it. However, note that tokens with longer lifespan can weaken the security of your system and make your application users vulnerable to security threats. Such use cases should be carefully planned and the security concerns should be addressed seriously.

API credentials flow for machine-to-machine automations

The API credentials represent an administrative user in Decidim that performs administrative tasks on behalf of the end users. This type of integration flows should never live on devices that the participants have access to. These types of integrations are meant for different types of automations, such as transferring proposal answers or meeting reports back to Decidim from an external system automatically, e.g. once a day.

Note that these credentials are highly sensitive and have elevated permissions, so take good care of the system security where you are planning to store these credentials. If these credentials end up in participants' hands, the whole system is compromised and no longer secure. You should always primarily create OAuth integrations where the end users will manually perform the authorization for the application to perform actions on behalf of them.

Once you have validated that this is the correct way for your integration to operate, you can create the API credentials from the system administration panel. You will receive an API key and API secret after creating the credentials. These credentials should be also manually rotated on a regular basis to prevent unauthorized access to the system with these credentials in case they are leaked. The credentials have to be manually rotated in order to prevent external applications breaking because they cannot rotate the credentials themselves and they are typically statically configured for these applications.

Given you have issued the API key and API secret, you can now send a sign in request to the API using these credentials as follows:

curl -s -i -H "Content-type: application/x-www-form-urlencoded" \
  -d "api_user[key]=PASTE_API_KEY_HERE" \
  -d "api_user[secret]=PASTE_API_SECRET_HERE" \
  -X POST https://DOMAIN/api/sign_in | grep 'Authorization' | cut -d ' ' -f2-

After running this command, you should see the following string in the console, where token is replaced with the access token:

Bearer token

This string is passed to the following requests within the HTTP Authorization header to represent the user during API calls. You can use the following example query to test it out and confirm that signing in works as expected:

curl -w "\n" -H "Content-Type: application/json" \
  -H "Authorization: Bearer token" \
  -d '{"query":"{ session { user { id name nickname } } }"}' \
  -X POST https://DOMAIN/api

Once the API interaction is done, you should always make an HTTP DELETE request to /api/sign_out with the same token in order to revoke the token from further access as follows:

curl -s -o /dev/null -w "HTTP %{http_code}\n" \
  -H "Authorization: Bearer token" \
  -X DELETE http://DOMAIN/api/sign_out