## "Configure AWS Credentials" Action For GitHub Actions

Configure AWS credential and region environment variables for use in other GitHub Actions.  The environment variables will be detected by both the AWS SDKs and the AWS CLI to determine the credentials and region to use for AWS API calls.

**Table of Contents**

<!-- toc -->

- [Usage](#usage)
- [Credentials](#credentials)
- [Assuming a Role](#assuming-a-role)
    + [Session tagging](#session-tagging)
    + [Sample IAM Role Permissions](#sample-iam-role-cloudformation-template)
- [Self-Hosted Runners](#self-hosted-runners)
- [License Summary](#license-summary)
- [Security Disclosures](#security-disclosures)

<!-- tocstop -->

## Usage

Add the following step to your workflow:

```yaml
    - name: Configure AWS Credentials
      uses: aws-actions/configure-aws-credentials@v1
      with:
        role-to-assume: arn:aws:iam::123456789100:role/my-github-actions-role
        aws-region: us-east-2
```

For example, you can use this action with the AWS CLI available in [GitHub's hosted virtual environments](https://help.github.com/en/actions/reference/software-installed-on-github-hosted-runners).
You can also run this action multiple times to use different AWS accounts, regions, or IAM roles in the same GitHub Actions workflow job.

```yaml
jobs:
  deploy:
    name: Upload to Amazon S3
    runs-on: ubuntu-latest
    # These permissions are needed to interact with GitHub's OIDC Token endpoint.
    permissions:
      id-token: write
      contents: read
    steps:
    - name: Checkout
      uses: actions/checkout@v2

    - name: Configure AWS credentials from Test account
      uses: aws-actions/configure-aws-credentials@v1
      with:
        role-to-assume: arn:aws:iam::111111111111:role/my-github-actions-role-test
        aws-region: us-east-1

    - name: Copy files to the test website with the AWS CLI
      run: |
        aws s3 sync . s3://my-s3-test-website-bucket

    - name: Configure AWS credentials from Production account
      uses: aws-actions/configure-aws-credentials@v1
      with:
        role-to-assume: arn:aws:iam::222222222222:role/my-github-actions-role-prod
        aws-region: us-west-2

    - name: Copy files to the production website with the AWS CLI
      run: |
        aws s3 sync . s3://my-s3-prod-website-bucket
```

See [action.yml](action.yml) for the full documentation for this action's inputs and outputs.

## Credentials

We recommend following [Amazon IAM best practices](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html) for the AWS credentials used in GitHub Actions workflows, including:
* Do not store credentials in your repository's code.
* [Grant least privilege](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#grant-least-privilege) to the credentials used in GitHub Actions workflows.  Grant only the permissions required to perform the actions in your GitHub Actions workflows.
* [Monitor the activity](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#keep-a-log) of the credentials used in GitHub Actions workflows.

## Assuming a Role
We recommend using GitHub's OIDC provider to get short-lived credentials needed for your actions. 
Specifying `role-to-assume` without providing an `aws-access-key-id` or a `web-identity-token-file` will signal to the action that you wish to use the OIDC provider.
The default session duration is 1 hour when using the OIDC provider to directly assume an IAM Role.
The default session duration is 6 hours when using an IAM User to assume an IAM Role (by providing an `aws-access-key-id`, `aws-secret-access-key`, and a `role-to-assume`) .
If you would like to adjust this you can pass a duration to `role-duration-seconds`, but the duration cannot exceed the maximum that was defined when the IAM Role was created.
The default session name is GitHubActions, and you can modify it by specifying the desired name in `role-session-name`.

The following table describes which identity is used based on which values are supplied to the Action:

| **Identity Used**                                                | `aws-access-key-id` | `role-to-assume` | `web-identity-token-file` |
|------------------------------------------------------------------|---------------------|------------------|---------------------------|
| [✅ Recommended] Assume Role directly using GitHub OIDC provider |                     | ✔                |                           |
| IAM User                                                         | ✔                   |                  |                           |
| Assume Role using IAM User credentials                           | ✔                   | ✔                |                           |
| Assume Role using WebIdentity Token File credentials             |                     | ✔                | ✔                         |

### Examples

```yaml
    - name: Configure AWS Credentials
      uses: aws-actions/configure-aws-credentials@v1
      with:
        aws-region: us-east-2
        role-to-assume: arn:aws:iam::123456789100:role/my-github-actions-role
        role-session-name: MySessionName
```
In this example, the Action will load the OIDC token from the GitHub-provided environment variable and use it to assume the role `arn:aws:iam::123456789100:role/my-github-actions-role` with the session name `MySessionName`.

```yaml
    - name: Configure AWS Credentials
      uses: aws-actions/configure-aws-credentials@v1
      with:
        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
        aws-region: us-east-2
        role-to-assume: ${{ secrets.AWS_ROLE_TO_ASSUME }}
        role-external-id: ${{ secrets.AWS_ROLE_EXTERNAL_ID }}
        role-duration-seconds: 1200
        role-session-name: MySessionName
```
In this example, the secret `AWS_ROLE_TO_ASSUME` contains a string like `arn:aws:iam::123456789100:role/my-github-actions-role`.  To assume a role in the same account as the static credentials, you can simply specify the role name, like `role-to-assume: my-github-actions-role`.

### Sample IAM Role CloudFormation Template
```yaml
Parameters:
  GitHubOrg:
    Type: String
  RepositoryName:
    Type: String
  OIDCProviderArn:
    Description: Arn for the GitHub OIDC Provider.
    Default: ""
    Type: String

Conditions:
  CreateOIDCProvider: !Equals 
    - !Ref OIDCProviderArn
    - ""

Resources:
  Role:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Action: sts:AssumeRoleWithWebIdentity
            Principal:
              Federated: !If 
                - CreateOIDCProvider
                - !Ref GithubOidc
                - !Ref OIDCProviderArn
            Condition:
              StringLike:
                token.actions.githubusercontent.com:sub: !Sub repo:${GitHubOrg}/${RepositoryName}:*

  GithubOidc:
    Type: AWS::IAM::OIDCProvider
    Condition: CreateOIDCProvider
    Properties:
      Url: https://token.actions.githubusercontent.com
      ClientIdList: 
        - sts.amazonaws.com
      ThumbprintList:
        - a031c46782e6e6c662c2c87c76da9aa62ccabd8e

Outputs:
  Role:
    Value: !GetAtt Role.Arn 
```

The GitHub OIDC Provider only needs to be created once per account (i.e. multiple IAM Roles that can be assumed by the GitHub's OIDC can share a single OIDC Provider)

### Session tagging
The session will have the name "GitHubActions" and be tagged with the following tags:
(`GITHUB_` environment variable definitions can be [found here](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/using-environment-variables#default-environment-variables))

| Key | Value|
| --- | --- |
| GitHub | "Actions" |
| Repository | GITHUB_REPOSITORY |
| Workflow | GITHUB_WORKFLOW |
| Action | GITHUB_ACTION |
| Actor | GITHUB_ACTOR |
| Branch | GITHUB_REF |
| Commit | GITHUB_SHA |

_Note: all tag values must conform to [the requirements](https://docs.aws.amazon.com/STS/latest/APIReference/API_Tag.html). Particularly, `GITHUB_WORKFLOW` will be truncated if it's too long. If `GITHUB_ACTOR` or `GITHUB_WORKFLOW` contain invalid characters, the characters will be replaced with an '*'._

The action will use session tagging by default during role assumption. 
Note that for WebIdentity role assumption, the session tags have to be included in the encoded WebIdentity token.
This means that Tags can only be supplied by the OIDC provider and not set during the AssumeRoleWithWebIdentity API call within the Action.
You can skip this session tagging by providing `role-skip-session-tagging` as true in the action's inputs:

```yaml
      uses: aws-actions/configure-aws-credentials@v1
      with:
        role-skip-session-tagging: true
```

## Self-Hosted Runners

If you run your GitHub Actions in a [self-hosted runner](https://help.github.com/en/actions/hosting-your-own-runners/about-self-hosted-runners) that already has access to AWS credentials, such as an EC2 instance, then you do not need to provide IAM user access key credentials to this action.

If no access key credentials are given in the action inputs, this action will use credentials from the runner environment using the [default methods for the AWS SDK for Javascript](https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/setting-credentials-node.html).

You can use this action to simply configure the region and account ID in the environment, and then use the runner's credentials for all AWS API calls made by your Actions workflow:
```yaml
uses: aws-actions/configure-aws-credentials@v1
with:
  aws-region: us-east-2
```
In this case, your runner's credentials must have permissions to call any AWS APIs called by your Actions workflow.

Or, you can use this action to assume a role, and then use the role credentials for all AWS API calls made by your Actions workflow:
```yaml
uses: aws-actions/configure-aws-credentials@v1
with:
  aws-region: us-east-2
  role-to-assume: my-github-actions-role
```
In this case, your runner's credentials must have permissions to assume the role.

You can also assume a role using a web identity token file, such as if using [Amazon EKS IRSA](https://docs.aws.amazon.com/eks/latest/userguide/iam-roles-for-service-accounts-technical-overview.html).
Pods running in EKS worker nodes that do not run as root can use this file to assume a role with a web identity.

You can configure your workflow as follows in order to use this file:
```yaml
uses: aws-actions/configure-aws-credentials@v1
with:
  aws-region: us-east-2
  role-to-assume: my-github-actions-role
  web-identity-token-file: /var/run/secrets/eks.amazonaws.com/serviceaccount/token
```

### Use with the AWS CLI

This workflow does _not_ install the [AWS CLI](https://aws.amazon.com/cli/) into your environment. Self-hosted runners that intend to run this action prior to executing `aws` commands need to have the AWS CLI [installed](https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-install.html) if it's not already present. 
Most [GitHub hosted runner environments](https://github.com/actions/virtual-environments) should include the AWS CLI by default.
 
## License Summary

This code is made available under the MIT license.

## Security Disclosures

If you would like to report a potential security issue in this project, please do not create a GitHub issue.  Instead, please follow the instructions [here](https://aws.amazon.com/security/vulnerability-reporting/) or [email AWS security directly](mailto:aws-security@amazon.com).