Add blog-post about downtream workflow

Signed-off-by: Frantisek Lachman <flachman@redhat.com>

content/posts/downstream-automation.md

@@ -0,0 +1,135 @@
+---
+title: "Downstream automation is here"
+date: 2022-03-02
+weight: 68
+---
+
+# Downstream automation is here
+
+Finally, it's here. Now, you can do the whole Fedora release with the help of Packit.
+Let's take a look at how this works on an example of [OGR](https://github.com/packit/ogr), the Python library we develop:
+
+## Upstream
+
+The process of releasing a new version starts in the upstream repository.
+Here, we can see an upstream release:
+
+![Upstream release](/images/downstream_workflow_upstream_release.png)
+
+## Propose downstream
+
+As the first step on our way to Fedora users, we need to get the new upstream release to the Fedora dist-git.
+This is what we call `propose-downstream` job.
+Here is a snippet from the config file of OGR:
+
+```yaml
+downstream_package_name: python-ogr
+copy_upstream_release_description: true
+
+jobs:
+  - job: propose_downstream
+    trigger: release
+    metadata:
+      dist_git_branches:
+        - fedora-all
+        - epel-8
+```
+
+How does the `propose-downstream` work?
+As a first step, the archive is saved to lookaside cache
+and after that, Packit updates the dist-git content (mainly `sources` file and spec-file)
+via pull-requests for the specified branches. (Direct push is possible by setting a
+[`create_pr` option](https://packit.dev/docs/configuration/#create_pr) to `false`.)
+
+As you can see in the config above, if you use `copy_upstream_release_description: true`,
+the changelog entry will use the GitHub release description field.
+(Just make sure the formatting is compatible with spec-file.
+E.g. use `-` instead of `*` for lists not to create multiple changelog entries.)
+
+And how it is triggered?
+Packit gets the information about the newly created release from GitHub (via webhook),
+load the config from the release commit and if there is a `propose-downstream` job
+defined, the workflow begins.
+
+Here are the pull-requests created by Packit:
+
+![List of downstream pull-requests created by Packit](/images/downstream_workflow_distgit_prs.png)
+
+And here are the details of the one created for `f35` branch:
+
+![Downstream pull-request created by Packit](/images/downstream_workflow_distgit_pr_detail.png)
+![Downstream pull-request created by Packit: changes in specfile](/images/downstream_workflow_distgit_pr_specfile.png)
+
+Now, it's on downstream CI systems and maintainer to check the changes and merge
+the pull-request.
+
+## Koji
+
+If Packit sees a new commit in the configured branch, it submits a new build in Koji
+like maintainers usually do. (The commits without any spec-file change are skipped.)
+
+![List of Koji builds triggered by Packit](/images/downstream_workflow_koji_builds.png)
+
+Here is a job definition for the package we use as an example:
+
+```yaml
+jobs:
+  - job: koji_build
+    trigger: commit
+    metadata:
+      dist_git_branches:
+        - fedora-all
+        - epel-8
+```
+
+There is no UI provided by Packit for the job,
+but it is visible across Fedora systems (like you can see in the following image)
+like a manually created Koji build and you can utilise
+[Fedora Notifications](https://apps.fedoraproject.org/notifications/about)
+to get informed about the builds.
+
+![Build status in merged downstream pull-request](/images/downstream_workflow_distgit_pr_build_status.png)
+
+## Bodhi
+
+Once Packit is informed (via fedora-messaging bus) about the successful Koji build,
+it creates a new update in Bodhi for you.
+
+![List of Bodhi updates created by Packit](/images/downstream_workflow_bodhi_updates.png)
+
+Here is a job definition:
+
+```yaml
+jobs:
+  - job: bodhi_update
+    trigger: commit
+    metadata:
+      dist_git_branches:
+        - fedora-stable # rawhide updates are created automatically
+        - epel-8
+```
+
+The packit config is loaded from the commit the build is triggered from.
+
+Here is an example of the resulting Bodhi update:
+
+![Bodhi update created by Packit](/images/downstream_workflow_bodhi_update_detail.png)
+
+And that's all. The rest is on the users and maintainers to give the update enough Karma
+so it reach the users.
+
+## Conclusion
+
+Does it look simple? Yes, it is. We try to automate
+as much as possible but still leave the space for human intervention where it is needed --
+pull-request review and verification of the Bodhi update.
+Of course, in case of some errors, a human can (and should)
+replace the work of a bot.
+Other manual, mundane and waiting tasks are replaced by Packit.
+
+Please, try it yourself and let us know what do you think.
+Those jobs are really new and some issues might occur.
+But we will try to fix those and if you have any suggestions
+for improvement, please, [create an issue]() so we can
+see if the request is doable and we can try to implement it.
+And of course, code contribution is more than welcome as well.