How to use a Google Secret in a deployed Cloud Run Service (managed)?

Question

I have a running cloud run service user-service. For test purposes I passed client secrets via environment variables as plain text. Now since everything is working fine I'd like to use a secret instead.

In the "Variables" tab of the "Edit Revision" option I can declare environment variables but I have no idea how to pass in a secret? Do I just need to pass the secret name like ${my-secret-id} in the value field of the variable? There is not documentation on how to use secrets in this tab only a hint at the top:

Store and consume secrets using Secret Manager

Which is not very helpful in this case.

Answer 1

UPDATE 2021: There is now a Cloud Run preview for loading secrets to an environment variable or a volume. https://cloud.google.com/run/docs/configuring/secrets

The question is now answered however I have been experiencing a similar problem using Cloud Run with Java & Quarkus and a native image created using GraalVM.

While Cloud Run is a really interesting technology at the time of writing it lacks the ability to load secrets through the Cloud Run configuration. This has certainly added complexity in my app when doing local development.

Additionally Google's documentation is really quite poor. The quick-start lacks a clear Java example for getting a secret[1] without it being set in the same method - I'd expect this to have been the most common use case!

The javadoc itself seems to be largely autogenerated with protobuf language everywhere. There are various similarly named methods like getSecret, getSecretVersion and accessSecretVersion

I'd really like to see some improvment from Google around this. I don't think it is asking too much for dedicated teams to make libraries for common languages with proper documentation.

Here is a snippet that I'm using to load this information. It requires the GCP Secret library and also the GCP Cloud Core library for loading the project ID.

public String getSecret(final String secretName) {
    LOGGER.info("Going to load secret {}", secretName);

    // SecretManagerServiceClient should be closed after request
    try (SecretManagerServiceClient client = buildClient()) {
        // Latest is an alias to the latest version of a secret
        final SecretVersionName name = SecretVersionName.of(getProjectId(), secretName, "latest");
        return client.accessSecretVersion(name).getPayload().getData().toStringUtf8();
    }
}

private String getProjectId() {

    if (projectId == null) {
        projectId = ServiceOptions.getDefaultProjectId();
    }

    return projectId;
}

private SecretManagerServiceClient buildClient() {
    try {
        return SecretManagerServiceClient.create();
    } catch(final IOException e) {
        throw new RuntimeException(e);
    }
}

[1] - https://cloud.google.com/secret-manager/docs/reference/libraries

Answer 2

Google have documentation for the Secret manager client libraries that you can use in your api.

This should help you do what you want https://cloud.google.com/secret-manager/docs/reference/libraries

Since you haven't specified a language I have a nodejs example of how to access the latest version of your secret using your project id and secret name. The reason I add this is because the documentation is not clear on the string you need to provide as the name.

 const [version] = await this.secretClient.accessSecretVersion({
        name: `projects/${process.env.project_id}/secrets/${secretName}/versions/latest`,
      });
 return version.payload.data.toString()

Be sure to allow secret manager access in your IAM settings for the service account that your api uses within GCP.

Answer 3

You can now read secrets from Secret Manager as environment variables in Cloud Run. This means you can audit your secrets, set permissions per secret, version secrets, etc, and your code doesn't have to change.

You can point to the secrets through the Cloud Console GUI (console.cloud.google.com) or make the configuration when you deploy your Cloud Run service from the command-line:

gcloud beta run deploy SERVICE --image IMAGE_URL --update-secrets=ENV_VAR_NAME=SECRET_NAME:VERSION

Six-minute video overview: https://youtu.be/JIE89dneaGo

Detailed docs: https://cloud.google.com/run/docs/configuring/secrets

Answer 4

I kinda found a way to use secrets as environment variables.

The following doc (https://cloud.google.com/sdk/gcloud/reference/run/deploy) states:

Specify secrets to mount or provide as environment variables. Keys starting with a forward slash '/' are mount paths. All other keys correspond to environment variables. The values associated with each of these should be in the form SECRET_NAME:KEY_IN_SECRET; you may omit the key within the secret to specify a mount of all keys within the secret. For example: '--update-secrets=/my/path=mysecret,ENV=othersecret:key.json' will create a volume with secret 'mysecret' and mount that volume at '/my/path'. Because no secret key was specified, all keys in 'mysecret' will be included. An environment variable named ENV will also be created whose value is the value of 'key.json' in 'othersecret'. At most one of these may be specified

Answer 5

Here is a snippet of Java code to get all secrets of your Cloud Run project. It requires the com.google.cloud/google-cloud-secretmanager artifact.

Map<String, String> secrets = new HashMap<>();          
String projectId;
String url = "http://metadata.google.internal/computeMetadata/v1/project/project-id";
HttpURLConnection conn = (HttpURLConnection)(new URL(url).openConnection());
conn.setRequestProperty("Metadata-Flavor", "Google");
try {
   InputStream in = conn.getInputStream();
   projectId = new String(in.readAllBytes(), StandardCharsets.UTF_8);
} finally {
   conn.disconnect();
}               
Set<String> names = new HashSet<>();
try (SecretManagerServiceClient client = SecretManagerServiceClient.create()) {
   ProjectName projectName = ProjectName.of(projectId);
   ListSecretsPagedResponse pagedResponse = client.listSecrets(projectName);
    
   pagedResponse
      .iterateAll()
      .forEach(secret -> { names.add(secret.getName()); });
   for (String secretName : names) {
      String name = secretName.substring(secretName.lastIndexOf("/") + 1);
      SecretVersionName nameParam = SecretVersionName.of(projectId, name, "latest");
      String secretValue = client.accessSecretVersion(nameParam).getPayload().getData().toStringUtf8();
      secrets.put(secretName, secretValue);
   }
}

Answer 6

Cloud Run support for referencing Secret Manager Secrets is now at general availability (GA).

https://cloud.google.com/run/docs/release-notes#November_09_2021