Use Emulator Credentials when using Firestore Emulator

describe the problem When trying to run CI/CD against a Firestore emulator instance (e.g. in GitHub Actions), tests were failing due to not finding the GOOGLE_APPLICATION_CREDENTIALS location. This was unexpected since we’d configured emulator=true, and it ofc wasn’t caught because we all have this already set on our local machines.

spring.cloud.gcp.firestore.emulator.enabled=true
spring.cloud.gcp.firestore.host-port=localhost:1234
spring.cloud.gcp.project-id=emulator

So, the workaround was to override the CredentialsProvider to explicitly use FirestoreOptions.EmulatorCredentials():

import com.google.api.gax.core.CredentialsProvider;
import com.google.auth.Credentials;
import com.google.cloud.firestore.FirestoreOptions;
//

@Configuration
public class SomeConfiguration {

  @Profile("integration-test")
  @Primary
  @Bean
  CredentialsProvider credentialsProvider() {
    return new CredentialsProvider() {
      @Override
      public Credentials getCredentials() throws IOException {
        return new FirestoreOptions.EmulatorCredentials();
      }
    };
  }
}

Describe the solution you’d like It’d be nice if this worked without further configuration; e.g. if CredentialsProvider used emulator credentials when emulator is enabled.

Describe alternatives you’ve considered I see in the source that CredentialsProvider always pulls from the location on the Credentials object, which makes sense since a lot of the GCP components don’t have emulator support. Might be tricky, if you don’t want to add some lines to check typeof Credentials.

Additional context None

[meltsufin]

Great point about impacting other services! You’re welcome to work on it. I just realized that we have already solved this problem in Pub/Sub. So, we don’t have to reinvent the solution. In Pub/Sub, we made GcpPubSubAutoConfiguration aware of the emulator setting. See this snippet:

	public GcpPubSubAutoConfiguration(GcpPubSubProperties gcpPubSubProperties,
			GcpProjectIdProvider gcpProjectIdProvider,
			CredentialsProvider credentialsProvider) throws IOException {
		this.gcpPubSubProperties = gcpPubSubProperties;
		this.finalProjectIdProvider = (gcpPubSubProperties.getProjectId() != null)
				? gcpPubSubProperties::getProjectId
				: gcpProjectIdProvider;

		if (gcpPubSubProperties.getEmulatorHost() == null
				|| "false".equals(gcpPubSubProperties.getEmulatorHost())) {
			this.finalCredentialsProvider = gcpPubSubProperties.getCredentials().hasKey()
					? new DefaultCredentialsProvider(gcpPubSubProperties)
					: credentialsProvider;
		}
		else {
			// Since we cannot create a general NoCredentialsProvider if the emulator host is enabled
			// (because it would also be used for the other components), we have to create one here
			// for this particular case.
			this.finalCredentialsProvider = NoCredentialsProvider.create();
		}
	}

A similar approach should work in the Firestore module. WDYT?

[garywg04]

Cool, look good to me. Let me try to follow the GcpPubSubAutoConfiguration and add the same handling to Firestore emulator.