Protect sensitive data using Secret Manager with Batch

This document describes how to protect sensitive data that you want to specify for a Batch job by using Secret Manager secrets.

Secret Manager secrets protect sensitive data through encryption. In a Batch job, you can specify one or more existing secrets to securely pass the sensitive data they contain, which you can use to do following:

Securely define custom environment variables that contain sensitive data.
Securely specify the login credentials for a Docker Registry to let a job's runnables access its private container images.

Before you begin

If you haven't used Batch before, review Get started with Batch and enable Batch by completing the prerequisites for projects and users.
Create a secret or identify a secret for the sensitive data that you want to securely specify for a job.
To get the permissions that you need to create a job, ask your administrator to grant you the following IAM roles:
- Batch Job Editor (roles/batch.jobsEditor) on the project
- Service Account User (roles/iam.serviceAccountUser) on the job's service account, which by default is the default Compute Engine service account
For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.
To ensure that the job's service account has the necessary permissions to access secrets, ask your administrator to grant the Secret Manager Secret Accessor (roles/secretmanager.secretAccessor) IAM role to the job's service account on the secret.
Important: You must grant this role to the job's service account, not to your user account. Failure to grant the role to the correct principal might result in permission errors.

Securely pass sensitive data to custom environment variables

To securely pass sensitive data from Secret Manager secrets to custom environment variables, you must define each environment variable in the secret variables (secretVariables) subfield for an environment and specify a secret for each value. Whenever you specify a secret in a job, you must format it as a path to a secret version: projects/PROJECT_ID/secrets/SECRET_ID/versions/VERSION.

You can create a job that defines secret variables by using the gcloud CLI, Batch API, Java, Node.js, or Python. The following example explains how to create a job that defines and uses a secret variable for the environment of all runnables (environment subfield of taskSpec).

gcloud

Create a JSON file that specifies the job's configuration details and include the secretVariables subfield for one or more environments.

For example, to create a basic script job that uses a secret variable in the environment for all runnables, create a JSON file with the following contents:
```
{
  "taskGroups": [
    {
      "taskSpec": {
        "runnables": [
          {
            "script": {
              "text": "echo This is the secret: ${SECRET_VARIABLE_NAME}"
            }
          }
        ],
        "environment": {
          "secretVariables": {
            "{SECRET_VARIABLE_NAME}": "projects/PROJECT_ID/secrets/SECRET_NAME/versions/VERSION"
          }
        }
      }
    }
  ],
  "logsPolicy": {
    "destination": "CLOUD_LOGGING"
  }
}
```
Replace the following:
- SECRET_VARIABLE_NAME: the name of the secret variable. By convention, environment variable names are capitalized.
  
  To securely access the sensitive data from the variable's Secret Manager secret, specify this variable name in this job's runnables. The secret variable is accessible to all of the runnables that are in the same environment where you define the secret variable.
- PROJECT_ID: the project ID of your project.
- SECRET_NAME: the name of an existing Secret Manager secret.
- VERSION: the version of the specified secret that contains the data you want to pass to the job. This can be the version number or latest.
To create and run the job, use the gcloud batch jobs submit command:
```
gcloud batch jobs submit JOB_NAME \
  --location LOCATION \
  --config JSON_CONFIGURATION_FILE
```
Replace the following:
- JOB_NAME: the name of the job.
- LOCATION: the location of the job.
- JSON_CONFIGURATION_FILE: the path for a JSON file with the job's configuration details.

API

Make a POST request to the jobs.create method that specifies the secretVariables subfield for one or more environments.

For example, to create a basic script job that uses a secret variable in the environment for all runnables, make the following request:

POST https://batch.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/jobs?job_id=JOB_NAME
{
  "taskGroups": [
    {
      "taskSpec": {
        "runnables": [
          {
            "script": {
              "text": "echo This is the secret: ${SECRET_VARIABLE_NAME}"
            }
          }
        ],
        "environment": {
          "secretVariables": {
            "{SECRET_VARIABLE_NAME}": "projects/PROJECT_ID/secrets/SECRET_NAME/versions/VERSION"
          }