Make Docker images generated by GitHub CI workflows available; minor CI fixes

[mkoeppe]

They are already tagged with meaningful names and just need to be pushed to a registry.

Now we push them to the registry provided by GitHub.
Example: https://github.com/mkoeppe/sage/runs/604103405 created https://github.com/mkoeppe/sage/packages/193111

Depends on #29341
Depends on #29534

CC: @kliem @vbraun @dimpase @embray @saraedum @slel

Component: porting

Keywords: ci, ContinuousIntegration

Author: Matthias Koeppe

Branch/Commit: 163562d

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/29530

[slel]

Changed keywords from none to ci

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,3 +1,7 @@
+They are already tagged with meaningful names and just need to be pushed to a registry.
+
+Also the CI workflows should be run `on: push: tags:` (https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags), not just `on: pull_requests`
+
 https://www.docker.com/blog/first-docker-github-action-is-here/
 
 https://github.com/actions/starter-workflows/blob/master/ci/docker-publish.yml

[dimpase]

comment:3

will it be possible to pull an image for letting cal inspection and debugging? cool.
(currently building a fedora 28 image locally...)

[mkoeppe]

Dependencies: #29341

[mkoeppe]

Changed keywords from ci to ci, ContinuousIntegration

[mkoeppe]

Changed dependencies from #29341 to #29341, #29534

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,6 +1,6 @@
 They are already tagged with meaningful names and just need to be pushed to a registry.
 
-Also the CI workflows should be run `on: push: tags:` (https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags), not just `on: pull_requests`
+Also the CI workflows should be run `on: push: tags:` (https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags), not just `on: pull_requests`; that's #29534.
 
 https://www.docker.com/blog/first-docker-github-action-is-here/
 

[mkoeppe]

comment:7

Replying to @dimpase:

will it be possible to pull an image for ... inspection and debugging?

Yes, that's the idea

[mkoeppe]

Branch: u/mkoeppe/make_docker_images_generated_by_github_ci_workflows_available

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

e506503	Add documentation
d6b64ba	tox-optional.yml: Push the docker images

[sagetrac-git]

Commit: d6b64ba

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,9 +1,4 @@
-They are already tagged with meaningful names and just need to be pushed to a registry.
+They are already tagged with meaningful names and just need to be pushed to a registry. 
 
-Also the CI workflows should be run `on: push: tags:` (https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags), not just `on: pull_requests`; that's #29534.
-
-https://www.docker.com/blog/first-docker-github-action-is-here/
-
-https://github.com/actions/starter-workflows/blob/master/ci/docker-publish.yml
-
-
+Now we push them to the registry provided by [GitHub](../wiki/GitHub).
+Example: https://github.com/mkoeppe/sage/runs/604103405 created https://github.com/mkoeppe/sage/packages/193111

[mkoeppe]

Author: Matthias Koeppe

[sagetrac-git]

Changed commit from d6b64ba to 06a9c39