# Docker Digest<no value>
// <!-- Required for asciidoctor -->
:toc:
// Set toclevels to be at least your hugo [markup.tableOfContents.endLevel] config key
:toclevels: 4

[cols="1^,1^,1^",options=header]
|===
| source | condition | target | scm
| &#10004; | &#10007; | &#10007; | &#10007;
|===

== Description

**source**

The Docker Digest "source" retrieves the Docker image digest for a specific Docker image tag.

== Parameters

{{< resourceparameters "sources" "dockerdigest" >}}

**Remark**:

It's considered a very bad practice to store credentials in an unencrypted file.
Consider using an environment variable to store the token.

== Authentication

Depending on the Docker Registry, authentication may be required. The way to retrieve the token depends on the registry.

=== GHCR

Github uses personal access token. How to retrieve one, is explained https://docs.github.com/en/free-pro-team@latest/github/authenticating-to-github/creating-a-personal-access-token[here]

=== DockerHub

To retrieve a token, it's easier to run `docker login` and then retrieve the token stored in '~/.docker/config.json'

.~/.docker/config.json
```
        "auths": {
                "https://index.docker.io/v1/": {
                        "auth": "token"
                }
        },
```

== Example

Please note that in this example we are using a go template `updatecli.tpl` with values from `values.yaml`
The main motivation is to use {{ requiredEnv ENV_VARIABLE }} to read the github token from a environment variable.

updatecli.tpl
```
sources:
  lastDockerDigest:
    kind: dockerdigest
    spec:
      image: "jenkins/jenkins"
      tag: "lts-jdk11"
targets:
  imageTag:
    name: "jenkins/jenkins:lts-jdk11 docker digest"
    kind: yaml
    spec:
      file: "config/default/jenkins-release.yaml"
      key: "jenkins.master.imageTag"
    scm:
      github:
        user: "{{ .github.user }}"
        email: "{{ .github.email }}"
        owner: "jenkins-infra"
        repository: "charts"
        token: "{{ requiredEnv .github.token }}"
        username: "{{ .github.username }}"
        branch: "master"
```

.values.yaml
```
github:
  user: "updatebot"
  email: "updatebot@olblak.com"
  username: "jenkins-infra-bot"
  token: "UPDATECLI_GITHUB_TOKEN"
  branch: "master"
  owner: "olblak"
  repository: "charts"
```

What it says:

**Source**
Retrieve the Docker image digest for the image `jenkins/jenkins` with the tag `lts-jdk11` from DockerHub

**Conditions**
No condition specified

**Targets**
Update the yaml key `jenkins.master.imageTag` in the file `config/default/jenkins-release.yaml` located on the Github repository `olblak/charts`