Encrypted secrets

About encrypted secrets

Secrets are variables that you create in an organization, repository, or repository environment. The secrets that you create are available to use in GitHub Actions workflows. GitHub Actions can only read a secret if you explicitly include the secret in a workflow.

For secrets stored at the organization-level, you can use access policies to control which repositories can use organization secrets. Organization-level secrets let you share secrets between multiple repositories, which reduces the need for creating duplicate secrets. Updating an organization secret in one location also ensures that the change takes effect in all repository workflows that use that secret.

For secrets stored at the environment level, you can enable required reviewers to control access to the secrets. A workflow job cannot access environment secrets until approval is granted by required approvers.

Naming your secrets

The following rules apply to secret names:

• Names can only contain alphanumeric characters ([a-z], [A-Z], [0-9]) or underscores (_). Spaces are not allowed.

• Names must not start with the GITHUB_ prefix.

• Names must not start with a number.

• Names are not case-sensitive.

• Names must be unique at the level they are created at.

  For example, a secret created at the environment level must have a unique name in that environment, a secret created at the repository level must have a unique name in that repository, and a secret created at the organization level must have a unique name at that level.

  If a secret with the same name exists at multiple levels, the secret at the lowest level takes precedence. For example, if an organization-level secret has the same name as a repository-level secret, then the repository-level secret takes precedence. Similarly, if an organization, repository, and environment all have a secret with the same name, the environment-level secret takes precedence.

To help ensure that GitHub redacts your secret in logs, avoid using structured data as the values of secrets. For example, avoid creating secrets that contain JSON or encoded Git blobs.

Accessing your secrets

To make a secret available to an action, you must set the secret as an input or environment variable in the workflow file. Review the action's README file to learn about which inputs and environment variables the action expects. For more information, see "Workflow syntax for GitHub Actions."

You can use and read encrypted secrets in a workflow file if you have access to edit the file. For more information, see "Access permissions on GitHub."

Organization and repository secrets are read when a workflow run is queued, and environment secrets are read when a job referencing the environment starts.

You can also manage secrets using the REST API. For more information, see "Actions."

Limiting credential permissions

When generating credentials, we recommend that you grant the minimum permissions possible. For example, instead of using personal credentials, use deploy keys or a service account. Consider granting read-only permissions if that's all that is needed, and limit access as much as possible.

When generating a personal access token, select the fewest scopes necessary.

Instead of using a personal access token, consider using a GitHub App, which uses fine-grained permissions and short lived tokens. Unlike a personal access token, a GitHub App is not tied to a user, so the workflow will continue to work even if the user who installed the app leaves your organization. For more information, see "Making authenticated API requests with a GitHub App in a GitHub Actions workflow."

Creating encrypted secrets for a repository

To create secrets for a personal account repository, you must be the repository owner. To create secrets for an organization repository, you must have admin access.

gh secret set SECRET_NAME

gh secret set SECRET_NAME < secret.txt

Creating encrypted secrets for an environment

To create secrets for an environment in a personal account repository, you must be the repository owner. To create secrets for an environment in an organization repository, you must have admin access. For more information on environments, see "Using environments for deployment."

gh secret set --env ENV_NAME SECRET_NAME

gh secret list --env ENV_NAME

Creating encrypted secrets for an organization

When creating a secret or variable in an organization, you can use a policy to limit access by repository. For example, you can grant access to all repositories, or limit access to only private repositories or a specified list of repositories.

To create secrets at the organization level, you must have admin access.

gh auth login --scopes "admin:org"

gh secret set --org ORG_NAME SECRET_NAME

gh secret set --org ORG_NAME SECRET_NAME --visibility all

gh secret set --org ORG_NAME SECRET_NAME --repos REPO-NAME-1, REPO-NAME-2"

gh secret list --org ORG_NAME

Reviewing access to organization-level secrets

You can check which access policies are being applied to a secret in your organization.

1. On your GitHub Enterprise Server instance, navigate to the main page of the organization.

2. Under your organization name, click Settings. If you cannot see the "Settings" tab, select the dropdown menu, then click Settings.

   

3. In the left sidebar, click Secrets.

4. The list of secrets includes any configured permissions and policies. For more details about the configured permissions for each secret, click Update.

Using encrypted secrets in a workflow

To provide an action with a secret as an input or environment variable, you can use the secrets context to access secrets you've created in your repository. For more information, see "Contexts" and "Workflow syntax for GitHub Actions."

steps:
  - name: Hello world action
    with: # Set the secret as an input
      super_secret: ${{ secrets.SuperSecret }}
    env: # Or as an environment variable
      super_secret: ${{ secrets.SuperSecret }}

Secrets cannot be directly referenced in if: conditionals. Instead, consider setting secrets as job-level environment variables, then referencing the environment variables to conditionally run steps in the job. For more information, see "Contexts" and jobs.<job_id>.steps[*].if.

If a secret has not been set, the return value of an expression referencing the secret (such as ${{ secrets.SuperSecret }} in the example) will be an empty string.

Avoid passing secrets between processes from the command line, whenever possible. Command-line processes may be visible to other users (using the ps command) or captured by security audit events. To help protect secrets, consider using environment variables, STDIN, or other mechanisms supported by the target process.

If you must pass secrets within a command line, then enclose them within the proper quoting rules. Secrets often contain special characters that may unintentionally affect your shell. To escape these special characters, use quoting with your environment variables. For example:

Example using Bash

steps:
  - shell: bash
    env:
      SUPER_SECRET: ${{ secrets.SuperSecret }}
    run: |
      example-command "$SUPER_SECRET"

Example using PowerShell

steps:
  - shell: pwsh
    env:
      SUPER_SECRET: ${{ secrets.SuperSecret }}
    run: |
      example-command "$env:SUPER_SECRET"

Example using Cmd.exe

steps:
  - shell: cmd
    env:
      SUPER_SECRET: ${{ secrets.SuperSecret }}
    run: |
      example-command "%SUPER_SECRET%"

Limits for secrets

You can store up to 1,000 organization secrets, 100 repository secrets, and 100 environment secrets.

A workflow created in a repository can access the following number of secrets:

• All 100 repository secrets.
• If the repository is assigned access to more than 100 organization secrets, the workflow can only use the first 100 organization secrets (sorted alphabetically by secret name).
• All 100 environment secrets.

Secrets are limited to 48 KB in size. To store larger secrets, see the "Storing large secrets" workaround below.

Storing large secrets

To use secrets that are larger than 48 KB, you can use a workaround to store encrypted secrets in your repository and save the decryption passphrase as a secret on GitHub. For example, you can use gpg to encrypt a file containing your secret locally before checking the encrypted file in to your repository on GitHub. For more information, see the "gpg manpage."

1. Run the following command from your terminal to encrypt the file containing your secret using gpg and the AES256 cipher algorithm. In this example, my_secret.json is the file containing the secret.

   gpg --symmetric --cipher-algo AES256 my_secret.json
   

2. You will be prompted to enter a passphrase. Remember the passphrase, because you'll need to create a new secret on GitHub that uses the passphrase as the value.

3. Create a new secret that contains the passphrase. For example, create a new secret with the name LARGE_SECRET_PASSPHRASE and set the value of the secret to the passphrase you used in the step above.

4. Copy your encrypted file to a path in your repository and commit it. In this example, the encrypted file is my_secret.json.gpg.

   Warning: Make sure to copy the encrypted my_secret.json.gpg file ending with the .gpg file extension, and not the unencrypted my_secret.json file.

   git add my_secret.json.gpg
   git commit -m "Add new encrypted secret JSON file"
   

5. Create a shell script in your repository to decrypt the secret file. In this example, the script is named decrypt_secret.sh.

   #!/bin/sh
   
   # Decrypt the file
   mkdir $HOME/secrets
   # --batch to prevent interactive command
   # --yes to assume "yes" for questions
   gpg --quiet --batch --yes --decrypt --passphrase="$LARGE_SECRET_PASSPHRASE" \
   --output $HOME/secrets/my_secret.json my_secret.json.gpg
   

6. Ensure your shell script is executable before checking it in to your repository.

   chmod +x decrypt_secret.sh
   git add decrypt_secret.sh
   git commit -m "Add new decryption script"
   git push
   

7. In your GitHub Actions workflow, use a step to call the shell script and decrypt the secret. To have a copy of your repository in the environment that your workflow runs in, you'll need to use the actions/checkout action. Reference your shell script using the run command relative to the root of your repository.

   name: Workflows with large secrets
   
   on: push
   
   jobs:
     my-job:
       name: My Job
       runs-on: ubuntu-latest
       steps:
         - uses: actions/checkout@v2
         - name: Decrypt large secret
           run: ./decrypt_secret.sh
           env:
             LARGE_SECRET_PASSPHRASE: ${{ secrets.LARGE_SECRET_PASSPHRASE }}
         # This command is just an example to show your secret being printed
         # Ensure you remove any print statements of your secrets. GitHub does
         # not hide secrets that use this workaround.
         - name: Test printing your secret (Remove this step in production)
           run: cat $HOME/secrets/my_secret.json
   

Storing Base64 binary blobs as secrets

You can use Base64 encoding to store small binary blobs as secrets. You can then reference the secret in your workflow and decode it for use on the runner. For the size limits, see "Encrypted secrets."

1. Use base64 to encode your file into a Base64 string. For example:

   $ base64 -i cert.der -o cert.base64
   

2. Create a secret that contains the Base64 string. For example:

   $ gh secret set CERTIFICATE_BASE64 < cert.base64
   ✓ Set secret CERTIFICATE_BASE64 for octocat/octorepo
   

3. To access the Base64 string from your runner, pipe the secret to base64 --decode. For example:

   name: Retrieve Base64 secret
   on:
     push:
       branches: [ octo-branch ]
   jobs:
     decode-secret:
       runs-on: ubuntu-latest
       steps:
         - uses: actions/checkout@v2
         - name: Retrieve the secret and decode it to a file
           env:
             CERTIFICATE_BASE64: ${{ secrets.CERTIFICATE_BASE64 }}
           run: |
             echo $CERTIFICATE_BASE64 | base64 --decode > cert.der
         - name: Show certificate information
           run: |
             openssl x509 -in cert.der -inform DER -text -noout