Update readme with renovate configuration for digest updates #514

To be able to use a digest value which is automatically updated by `renovate` a custom "regexManager" is required.

Here's an examplary `values.yml` definition which makes use of a digest:

`pullPolicy: IfNotPresent` can be removed here

By default renovate adds the digest after the tag. To comply with the Gitea helm chart definition of the digest parameter, a custom "regexManager" definition is required:

"Apply an explicit gitea digest field match"

`"fileMatch": ["values\\.yaml|values\\.yml"]`

I will do it with `"values\\.ya?ml"` to make `a` optional.

I think this sentence could be removed, the parameter scope should be quite clear.

We should name Renovate with capital R. It's how they spell themselves. And probably link to https://docs.renovatebot.com/configuration-options/#regexmanagers.

They renamed `regexManager` to `customManagers` so following that I've updated configuration https://github.com/renovatebot/renovate/pull/24451

- gitea: - image: - repository: gitea/gitea - tag: 1.20.2 - digest: sha256:6e3b85a36653894d6741d0aefb41dfaac39044e028a42e0a520cc05ebd7bfc3f + image: + repository: gitea/gitea + tag: 1.20.2 + digest: sha256:6e3b85a36653894d6741d0aefb41dfaac39044e028a42e0a520cc05ebd7bfc3f 

The image specification is on top level of `values.yaml` ```diff - gitea: - image: - repository: gitea/gitea - tag: 1.20.2 - digest: sha256:6e3b85a36653894d6741d0aefb41dfaac39044e028a42e0a520cc05ebd7bfc3f + image: + repository: gitea/gitea + tag: 1.20.2 + digest: sha256:6e3b85a36653894d6741d0aefb41dfaac39044e028a42e0a520cc05ebd7bfc3f ```

Same as above: Renovate with capital R.

 { "description": "Apply an explicit gitea digest field match", "fileMatch": ["values\\.ya?ml"], - "matchStrings": ["(?<depName>gitea\\/gitea)\\n.*?tag: (?<currentValue>[^@].*?)\\n.*?digest: (?<currentDigest>sha256:[a-f0-9]+)"], + "matchStrings": ["(?<depName>gitea\\/gitea)\\n(?<indentation>\\s+)tag: (?<currentValue>[^@].*?)\\n\\s+digest: (?<currentDigest>sha256:[a-f0-9]+)"],  "datasourceTemplate": "docker", - "autoReplaceStringTemplate": "{{depName}}\n tag: {{newValue}}\n digest: {{#if newDigest}}{{{newDigest}}}{{else}}{{{currentDigest}}}{{/if}}" + "autoReplaceStringTemplate": "{{depName}}\n{{indentation}}tag: {{newValue}}\n{{indentation}}digest: {{#if newDigest}}{{{newDigest}}}{{else}}{{{currentDigest}}}{{/if}}"  } 

The `matchStrings` pattern matches non-compliant strings (https://regex101.com/r/G43cMf/1). I suggest the following changes to the configuration to: - fix the non-compliant matches (https://regex101.com/r/GIFmH1/1) - have dynamic indentation ([Renovate documentation](https://docs.renovatebot.com/templates/#other-available-fields:~:text=has%20release%20notes-,indentation,-%3A%20The%20indentation%20of)) ```diff { "description": "Apply an explicit gitea digest field match", "fileMatch": ["values\\.ya?ml"], - "matchStrings": ["(?<depName>gitea\\/gitea)\\n.*?tag: (?<currentValue>[^@].*?)\\n.*?digest: (?<currentDigest>sha256:[a-f0-9]+)"], + "matchStrings": ["(?<depName>gitea\\/gitea)\\n(?<indentation>\\s+)tag: (?<currentValue>[^@].*?)\\n\\s+digest: (?<currentDigest>sha256:[a-f0-9]+)"], "datasourceTemplate": "docker", - "autoReplaceStringTemplate": "{{depName}}\n tag: {{newValue}}\n digest: {{#if newDigest}}{{{newDigest}}}{{else}}{{{currentDigest}}}{{/if}}" + "autoReplaceStringTemplate": "{{depName}}\n{{indentation}}tag: {{newValue}}\n{{indentation}}digest: {{#if newDigest}}{{{newDigest}}}{{else}}{{{currentDigest}}}{{/if}}" } ```

Nice solution with the `indentation`.