Update maintenance readme.

README-MAINTENANCE.md

@@ -6,30 +6,90 @@ The structure and usage of this repository is influenced by other, official dock
 
 **This is important!**
 
-Never ever change a file/folder inside a directory without a `.` at the beginning (`2018.05-rc`, ...).
+The `update.sh` script automatically deletes all non-`.`-directories (= version directories) at first.
+
+Never ever change a file/folder inside a directory without a `.` a t the beginning (`2018.05-rc`, ...).
 This folder will get updated automatically based on the templates you want to change.
 All changes in such folders will get overwritten during an update.
 
-# Maintenance scripts
+# How to update
 
-# `update.sh`
+This section describes how to update the official Friendica docker images.
+The official docker image is available at https://hub.docker.com/_/friendica.
 
-Creates a directory and the necessary files for each combination of version (2018.05-rc, 3.6, ...) and variant (apache, fpm, fpm-alpine):
+## How to update the Docker Image
+
+1. Review your changes based on the official Docker [Review guidelines](https://github.com/docker-library/official-images#review-guidelines). 
+2. Check for a new stable version (see chapter `generate-stackbrew-library.sh`)
+3. Check if you have to adjust the minimum version (see chapter `update.sh`)
+4. Check if all tests are green (common issue: you forgot to commit all changes because of `update.sh`)
+5. Check if all commits are available at the stable branch (= all required PRs are committed into stable)
+6. Download & install [`bashbrew`](https://github.com/docker-library/bashbrew)
+7. Execute `generate-stackbrew-library.sh`
+8. Copy the output & overwrite the whole official Friendica [docker manifest](https://github.com/docker-library/official-images/blob/master/library/friendica).
+9. Create a new PR at https://github.com/docker-library/official-images/pulls
+
+After the PR is merged, the images aren't immediately available, they've to get build.
+Check the official Docker Continuous Deployment server https://doi-janky.infosiftr.net/job/multiarch/ for the current status of the builds.
+
+## How to update the docker hub description
+
+1. At first, read https://github.com/docker-library/docs#how-do-i-update-an-images-docs
+2. Checkout & change the content of https://github.com/docker-library/docs/tree/master/friendica
+3. Create a new Pull Request at https://github.com/docker-library/docs/pulls 
+
+# Tools & Scripts
+
+## Github Action
+
+GitHub Actions helps to automate tasks for Continuous Integration (= autotest docker images) and Continuous Deployment (= autocreate docker images based on the friendica upstream).
+
+For mor details see [Introduction to github actions](https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/introduction-to-github-actions).
+
+### [`update-sh.yml`](https://github.com/friendica/docker/blob/stable/.github/workflows/update-sh.yml)
+
+This script is a cronjob every 15 minutes and automatically runs `update.sh`.
+In case there are changes because of `update.sh`, it starts `images.yml`.
+
+### [`images.yml`](https://github.com/friendica/docker/blob/stable/.github/workflows/images.yml)
+
+This script automatically creates autotests actions based on the docker image version structure and variants.
+For example if there are two versions (like `2021.03-dev` and `2021.01`), it would create 3 runs (apache, apache-fpm, fpm-alpine) for each version, having 6 runs at all.
+
+Therefore, the script uses the official docker github action tool [`bashbrew`](https://github.com/docker-library/bashbrew.git) to transform the repository version structure into github action commands
+
+This workflow is automatically executed because of a PR, a commit to `stable` or if the cronjob has found new updates.
+
+## Maintenance scripts
+
+### [`update.sh`](https://github.com/friendica/docker/blob/stable/update.sh)
+   
+Creates a directory, and the necessary files for each combination of version (2018.05-rc, 3.6, ...) and variant (apache, fpm, fpm-alpine):
 
 - Creating the right `Dockerfile` (from one of the two *.template files)
 - Copy each config file in `.config/`
 - Recreating the version/variant environment in `.travis.yml` 
 
-If you want to update the Docker-images to a newer version, just change the list in `update.sh` at
+All possible Friendica versions are retrieved from https://files.friendi.ca/.
-```shell
-versions=(
-  2018.05-rc
-)
-```
 
-# `generate-stackbrew-library.sh`
+#### Version patterns
 
-This file automatically creates a "manifest" for the docker-images.
+The update script parses the source https://files.friendi.ca/ automatically based on these patterns:
+- stable: `friendica-full-%YYYY%.%MM%.tar.gz` (e.g. `friendica-full-2021.10.tar.gz`)
+- dev/rc: `friendica-full-%YYYY%.%MM%-dev/rc.tar.gz` (e.g. `friendica-full-2021.10-dev.tar.gz`)
+- hotfix: `friendica-full-%YYYY%.%MM%-%i.tar.gz` (e.g. `friendica-full-2021.10-01.tar.gz`)
+   
+Any other pattern will completely be ignored(!)
+
+#### Minimum version
+
+Please adjust the `min_version` variable.
+It contains the minimum supported version, which will automatically be available as a docker image.
+Any other versions lower than this won't be available from the official docker hub anymore.
+
+### [`generate-stackbrew-library.sh`](https://github.com/friendica/docker/blob/stable/generate-stackbrew-library.sh)
+
+This file creates a "manifest" for the docker-images.
 This "manifest" is used to create a new PR in the official-images [repository](https://github.com/docker-library/official-images/) for deploying the changes to the docker hub.
 Like:
 
@@ -54,3 +114,9 @@ GitCommit: b46fae917321394e1482df59dc4e39daffbe5c59
 Directory: 2018.05-rc/fpm-alpine
 This is the input-file for the official-images in a later step :-)
 ```
+
+#### Release channels
+
+Please adjust the `release_channel` array.
+It maps additional tags onto docker image versions.
+Most important is the `stable` tag.