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Configuring OpenID Connect in HashiCorp Vault

Use OpenID Connect within your workflows to authenticate with 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

  • 若要了解 GitHub 如何使用 OpenID Connect (OIDC) 及其体系结构和优势的基本概念,请参阅“关于使用 OpenID Connect 加强安全性”。

  • 在继续之前,必须规划安全策略,以确保仅以可预测的方式分配访问令牌。 要控制云提供商颁发访问令牌的方式,必须至少定义一个条件,以便不受信任的存储库无法为云资源请求访问令牌。 有关详细信息,请参阅“通过云配置 OIDC 信任”。

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:

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

Adding permissions settings

作业或工作流运行需要具有 id-token: writepermissions 设置。 如果 id-tokenpermissions 设置已设置为 readnone,则无法请求 OIDC JWT ID 令牌。

id-token: write 设置允许使用下列方法之一从 GitHub 的 OIDC 提供程序请求 JWT:

  • 在运行器上使用环境变量(ACTIONS_ID_TOKEN_REQUEST_URLACTIONS_ID_TOKEN_REQUEST_TOKEN)。
  • 使用“操作”工具包中的 getIDToken()

如果需要为工作流提取 OIDC 令牌,则可以在工作流级别设置权限。 例如:

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

如果只需要为单个作业提取 OIDC 令牌,则可在该作业中设置此权限。 例如:

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

可能需要在此处指定额外权限,具体取决于你的工作流要求。

Note:

When the permissions key is used, all unspecified permissions are set to no access, with the exception of the metadata scope, which always gets read access. As a result, you may need to add other permissions, such as contents: read. See Automatic token authentication for more information.

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.
YAML
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.

Note:

  • If your Vault server is not accessible from the public network, consider using a self-hosted runner with other available Vault auth methods. For more information, see "About self-hosted runners."
  • <Vault Namespace> must be set for a Vault Enterprise (including HCP Vault) deployment. For more information, see Vault namespace.

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.
YAML
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