docker-build-push/docs/advanced/secrets.md

# Secrets

In the following example we will expose and use the [GITHUB_TOKEN secret](https://docs.github.com/en/actions/security-guides/automatic-token-authentication#about-the-github_token-secret)
as provided by GitHub in your workflow.

First let's create our `Dockerfile` to use our secret:

```dockerfile
# syntax=docker/dockerfile:1
FROM alpine
RUN --mount=type=secret,id=github_token \
  cat /run/secrets/github_token
```

As you can see we have named our secret `github_token`. Here is the workflow
you can use to expose this secret using the [`secrets` input](../../README.md#inputs):

```yaml
name: ci

on:
  push:
    branches:
      - 'main'

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v3
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v2
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v2
      -
        name: Build
        uses: docker/build-push-action@v3
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          tags: user/app:latest
          secrets: |
            "github_token=${{ secrets.GITHUB_TOKEN }}"
```

> **Note**
>
> You can also expose a secret file to the build with the [`secret-files`](../../README.md#inputs) input:
> ```yaml
> secret-files: |
>   "MY_SECRET=./secret.txt"
> ```

If you're using [GitHub secrets](https://docs.github.com/en/actions/security-guides/encrypted-secrets)
and need to handle multi-line value, you will need to place the key-value pair
between quotes:

```yaml
secrets: |
  "MYSECRET=${{ secrets.GPG_KEY }}"
  GIT_AUTH_TOKEN=abcdefghi,jklmno=0123456789
  "MYSECRET=aaaaaaaa
  bbbbbbb
  ccccccccc"
  FOO=bar
  "EMPTYLINE=aaaa
  
  bbbb
  ccc"
  "JSON_SECRET={""key1"":""value1"",""key2"":""value2""}"
```

| Key                | Value                               |
|--------------------|-------------------------------------|
| `MYSECRET`         | `***********************`           |
| `GIT_AUTH_TOKEN`   | `abcdefghi,jklmno=0123456789`       |
| `MYSECRET`         | `aaaaaaaa\nbbbbbbb\nccccccccc`      |
| `FOO`              | `bar`                               |
| `EMPTYLINE`        | `aaaa\n\nbbbb\nccc`                 |
| `JSON_SECRET`      | `{"key1":"value1","key2":"value2"}` |

> **Note**
>
> All quote signs need to be doubled for escaping.