ci: Test upgrades from the minimum of each major version, not the max.

.github/workflows/production-suite.yml

@@ -213,16 +213,16 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          # Docker images are built from 'tools/ci/Dockerfile'; the comments at
+          # Docker images are built from 'tools/ci/Dockerfile.prod'; the comments at
           # the top explain how to build and upload these images.
-          - docker_image: zulip/ci:focal-3.4
-            name: 3.4 Version Upgrade
+          - docker_image: zulip/ci:focal-3.2
+            name: 3.2 Version Upgrade
             os: focal
-          - docker_image: zulip/ci:bullseye-4.11
-            name: 4.11 Version Upgrade
+          - docker_image: zulip/ci:bullseye-4.2
+            name: 4.2 Version Upgrade
             os: bullseye
-          - docker_image: zulip/ci:bullseye-5.3
-            name: 5.3 Version Upgrade
+          - docker_image: zulip/ci:bullseye-5.0
+            name: 5.0 Version Upgrade
             os: bullseye
 
     name: ${{ matrix.name  }}

docs/subsystems/release-checklist.md

@@ -78,15 +78,6 @@ preparing a new release.
 - The DigitalOcean one-click image will report in an internal channel
   once it is built, and how to test it. Verify it, then publish it
   publish it to DigitalOcean marketplace.
-- Update the CI targets:
-  - _Major releases only:_ In all of the following steps, _also_
-    bump up the series that are being tested.
-  - Update the version in `tools/ci/build-docker-images`
-  - Run `tools/ci/build-docker-images`
-  - Push at least the latest of those, e.g. using `docker push zulip/ci:bullseye-4.11`; update the others at your discretion.
-  - Update the `docker_image` in the `production_upgrade` step of
-    `.github/workflows/production-suite.yml`.
-  - Commit those two changes in a PR.
 - _Major releases only:_
   - Create a release branch (e.g. `4.x`).
   - On the release branch, update `ZULIP_VERSION` in `version.py` to
@@ -101,6 +92,10 @@ preparing a new release.
   - Update Transifex to add the new `4.x` style release branch
     resources and archive the previous release branch's resources with
     the "Translations can't translate this resource" setting.
+  - Add a new CI production upgrade target:
+    - Build a docker image: `cd tools/ci && docker build . -f Dockerfile.prod --build-arg=BASE_IMAGE=zulip/ci:bullseye --build-arg=VERSION=5.0 --tag=zulip/ci:bullseye-5.0 && docker push zulip/ci:bullseye-5.0`
+    - Add a new line to the `production_upgrade` matrix in
+      `.github/workflows/production-suite.yml`.
 - _Minor releases only (e.g. 3.2):_
   - On the release branch, update `ZULIP_VERSION` to the present
     release with a `+git` suffix, e.g. `3.2+git`.

tools/ci/Dockerfile.prod

@@ -1,7 +1,10 @@
-# To build these production upgrade test images, say an Ubuntu 20.04 Focal system
-# preinstalled with Zulip 3.4:
-#   docker build . -f Dockerfile.prod --build-arg=BASE_IMAGE=zulip/ci:focal --build-arg=VERSION=3.4 --tag=zulip/ci:focal-3.4
-#   docker push zulip/ci:focal-3.4
+# To build these production upgrade test images, say an Debian 11 Bullseye system
+# preinstalled with Zulip 5.0:
+#   docker build . -f Dockerfile.prod \
+#     --build-arg=BASE_IMAGE=zulip/ci:bullseye \
+#     --build-arg=VERSION=5.0 \
+#     --tag=zulip/ci:focal-5.0
+#   docker push zulip/ci:focal-5.0
 
 ARG BASE_IMAGE
 FROM $BASE_IMAGE

tools/ci/build-docker-images

@@ -4,6 +4,3 @@ cd "$(dirname "${BASH_SOURCE[0]}")"
 docker build . --build-arg=BASE_IMAGE=ubuntu:20.04 --pull --tag=zulip/ci:focal
 docker build . --build-arg=BASE_IMAGE=ubuntu:22.04 --pull --tag=zulip/ci:jammy
 docker build . --build-arg=BASE_IMAGE=debian:11 --pull --tag=zulip/ci:bullseye
-docker build . -f Dockerfile.prod --build-arg=BASE_IMAGE=zulip/ci:focal --build-arg=VERSION=3.4 --tag=zulip/ci:focal-3.4
-docker build . -f Dockerfile.prod --build-arg=BASE_IMAGE=zulip/ci:bullseye --build-arg=VERSION=4.11 --tag=zulip/ci:bullseye-4.11
-docker build . -f Dockerfile.prod --build-arg=BASE_IMAGE=zulip/ci:bullseye --build-arg=VERSION=5.3 --tag=zulip/ci:bullseye-5.3