Configuring OpenID Connect in HashiCorp Vault

Overview

OpenID Connect (OIDC) allows your GitHub Actions workflows to authenticate with a HashiCorp Vault to retrieve secrets.

This guide gives an overview of how to configure HashiCorp Vault to trust GitHub's OIDC as a federated identity, and demonstrates how to use this configuration in the hashicorp/vault-action action to retrieve secrets from HashiCorp Vault.

Prerequisites

• Para saber os conceitos básicos de como o GitHub usa o OIDC (OpenID Connect), além da arquitetura e dos benefícios, confira "Sobre a proteção de segurança com o OpenID Connect".

• Antes de prosseguir, você deve planejar sua estratégia de segurança para garantir que os tokens de acesso sejam atribuídos apenas de forma previsível. Para controlar como o provedor de nuvem emite os tokens de acesso, você precisa definir, pelo menos, uma condição, para que os repositórios não confiáveis não possam solicitar tokens de acesso aos seus recursos de nuvem. Para obter mais informações, confira "Como configurar a relação de confiança do OIDC com a nuvem".

Adding the identity provider to HashiCorp Vault

To use OIDC with HashiCorp Vault, you will need to add a trust configuration for the GitHub OIDC provider. For more information, see the HashiCorp Vault documentation.

To configure your Vault server to accept JSON Web Tokens (JWT) for authentication:

1. Enable the JWT auth method, and use write to apply the configuration to your Vault. For oidc_discovery_url and bound_issuer parameters, use https://token.actions.githubusercontent.com. These parameters allow the Vault server to verify the received JSON Web Tokens (JWT) during the authentication process.

   Shell

   vault auth enable jwt

   Shell

   vault write auth/jwt/config \
     bound_issuer="https://token.actions.githubusercontent.com" \
     oidc_discovery_url="https://token.actions.githubusercontent.com"

2. Configure a policy that only grants access to the specific paths your workflows will use to retrieve secrets. For more advanced policies, see the HashiCorp Vault Policies documentation.

   Shell

   vault policy write myproject-production - <<EOF
   # Read-only permission on 'secret/data/production/*' path
   
   path "secret/data/production/*" {
     capabilities = [ "read" ]
   }
   EOF

3. Configure roles to group different policies together. If the authentication is successful, these policies are attached to the resulting Vault access token.

   Shell

   vault write auth/jwt/role/myproject-production -<<EOF
   {
     "role_type": "jwt",
     "user_claim": "actor",
     "bound_claims": {
       "repository": "user-or-org-name/repo-name"
     },
     "policies": ["myproject-production"],
     "ttl": "10m"
   }
   EOF

• ttl defines the validity of the resulting access token.
• Ensure that the bound_claims parameter is defined for your security requirements, and has at least one condition. Optionally, you can also set the bound_subject as well as the bound_audiences parameter.
• To check arbitrary claims in the received JWT payload, the bound_claims parameter contains a set of claims and their required values. In the above example, the role will accept any incoming authentication requests from the repo-name repository owned by the user-or-org-name account.
• To see all the available claims supported by GitHub's OIDC provider, see "Configuring the OIDC trust with the cloud".

For more information, see the HashiCorp Vault documentation.

Updating your GitHub Actions workflow

To update your workflows for OIDC, you will need to make two changes to your YAML:

1. Add permissions settings for the token.
2. Use the hashicorp/vault-action action to exchange the OIDC token (JWT) for a cloud access token.

To add OIDC integration to your workflows that allow them to access secrets in Vault, you will need to add the following code changes:

• Grant permission to fetch the token from the GitHub OIDC provider:
  • The workflow needs permissions: settings with the id-token value set to write. This lets you fetch the OIDC token from every job in the workflow.
• Request the JWT from the GitHub OIDC provider, and present it to HashiCorp Vault to receive an access token:
  • You can use the hashicorp/vault-action action to fetch the JWT and receive the access token from Vault, or you could use the Actions toolkit to fetch the tokens for your job.

This example demonstrates how to use OIDC with the official action to request a secret from HashiCorp Vault.

Adding permissions settings

A execução de trabalho ou de fluxo de trabalho exige uma configuração permissions com id-token: write. Você não poderá solicitar o token de ID JWT do OIDC se a configuração permissions de id-token for definida como read ou none.

A configuração id-token: writepermite que o JWT seja solicitado do provedor OIDC do GitHub usando uma destas abordagens:

• Usando variáveis de ambiente no executor (ACTIONS_ID_TOKEN_REQUEST_URL e ACTIONS_ID_TOKEN_REQUEST_TOKEN).
• Usando getIDToken() por meio do kit de ferramentas do Actions.

Se você precisar buscar um token OIDC para um fluxo de trabalho, a permissão poderá ser definida no nível do fluxo de trabalho. Por exemplo:

permissions:
  id-token: write # This is required for requesting the JWT
  contents: read  # This is required for actions/checkout

Se você só precisa obter um token OIDC para um único trabalho, essa permissão poderá ser definida dentro desse trabalho. Por exemplo:

permissions:
  id-token: write # This is required for requesting the JWT

Você pode precisar especificar permissões adicionais aqui, dependendo das necessidades do seu fluxo de trabalho.

Requesting the access token

The hashicorp/vault-action action receives a JWT from the GitHub OIDC provider, and then requests an access token from your HashiCorp Vault instance to retrieve secrets. For more information, see the HashiCorp Vault GitHub Action documentation.

This example demonstrates how to create a job that requests a secret from HashiCorp Vault.

• <Vault URL>: Replace this with the URL of your HashiCorp Vault.
• <Vault Namespace>: Replace this with the Namespace you've set in HashiCorp Vault. For example: admin.
• <Role name>: Replace this with the role you've set in the HashiCorp Vault trust relationship.
• <Secret-Path>: Replace this with the path to the secret you're retrieving from HashiCorp Vault. For example: secret/data/production/ci npmToken.

jobs:
  retrieve-secret:
    runs-on: ubuntu-latest
    permissions:
      id-token: write
      contents: read
    steps:
      - name: Retrieve secret from Vault
        uses: hashicorp/vault-action@v2.4.0
          with:
            method: jwt
            url: <Vault URL>
            namespace: <Vault Namespace - HCP Vault and Vault Enterprise only>
            role: <Role name>
            secrets: <Secret-Path>
                
      - name: Use secret from Vault
        run: |
          # This step has access to the secret retrieved above; see hashicorp/vault-action for more details.

Revoking the access token

By default, the Vault server will automatically revoke access tokens when their TTL is expired, so you don't have to manually revoke the access tokens. However, if you do want to revoke access tokens immediately after your job has completed or failed, you can manually revoke the issued token using the Vault API.

1. Set the exportToken option to true (default: false). This exports the issued Vault access token as an environment variable: VAULT_TOKEN.
2. Add a step to call the Revoke a Token (Self) Vault API to revoke the access token.

jobs:
  retrieve-secret:
    runs-on: ubuntu-latest
    permissions:
      id-token: write
      contents: read
    steps:
      - name: Retrieve secret from Vault
        uses: hashicorp/vault-action@v2.4.0
          with:
            exportToken: true
            method: jwt
            url: <Vault URL>
            role: <Role name>
            secrets: <Secret-Path>

      - name: Use secret from Vault
        run: |
          # This step has access to the secret retrieved above; see hashicorp/vault-action for more details.

      - name: Revoke token
        # This step always runs at the end regardless of the previous steps result
        if: always()
        run: |
          curl -X POST -sv -H "X-Vault-Token: ${{ env.VAULT_TOKEN }}" \
            <Vault URL>/v1/auth/token/revoke-self