docs: autogenerate tested k8s versions and centralize config

.devcontainer/pre-build.sh

@@ -1,13 +1,14 @@
 #!/usr/bin/env sh
 set -eux
 
-# install kubernetes
+# install kubernetes using the minimum tested version
+K8S_VERSION=$(./hack/k8s-versions.sh | head -n1)
 wget -q -O - https://raw.githubusercontent.com/k3d-io/k3d/main/install.sh | bash
-k3d cluster get k3s-default || k3d cluster create --image rancher/k3s:v1.29.10-k3s1 --wait
+k3d cluster get k3s-default || k3d cluster create --image "rancher/k3s:${K8S_VERSION}-k3s1" --wait
 k3d kubeconfig merge --kubeconfig-merge-default
 
 # install kubectl
-curl -LO https://dl.k8s.io/release/v1.29.10/bin/linux/$(go env GOARCH)/kubectl
+curl -LO "https://dl.k8s.io/release/${K8S_VERSION}/bin/linux/$(go env GOARCH)/kubectl"
 chmod +x ./kubectl
 sudo mv ./kubectl /usr/local/bin/kubectl
 kubectl cluster-info

.github/workflows/ci-build.yaml

@@ -318,6 +318,7 @@ jobs:
       - name: Install and start K3S
         run: |
           if ! echo "${{ matrix.install_k3s_version }}" | egrep '^v[0-9]+\.[0-9]+\.[0-9]+\+k3s1$'; then
+            # WARNING: The following line is grepped by hack/k8s-versions.sh, so don't change the format, just the version.
             export INSTALL_K3S_VERSION=v1.32.1+k3s1
           else
             export INSTALL_K3S_VERSION=${{ matrix.install_k3s_version }}

.spelling

@@ -187,6 +187,7 @@ liveness
 localhost
 maxFailures
 maxSuccess
+md
 memoization
 memoized
 memoizing

Makefile

@@ -718,7 +718,7 @@ endif
 .PHONY: docs-spellcheck
 docs-spellcheck: /usr/local/bin/mdspell docs/metrics.md
 	# check docs for spelling mistakes
-	mdspell --ignore-numbers --ignore-acronyms --en-us --no-suggestions --report $(shell find docs -name '*.md' -not -name upgrading.md -not -name README.md -not -name fields.md -not -name upgrading.md -not -name executor_swagger.md -not -path '*/cli/*')
+	mdspell --ignore-numbers --ignore-acronyms --en-us --no-suggestions --report $(shell find docs -name '*.md' -not -name upgrading.md -not -name README.md -not -name fields.md -not -name upgrading.md -not -name executor_swagger.md -not -path '*/cli/*' -not -name tested-kubernetes-versions.md)
 	# alphabetize spelling file -- ignore first line (comment), then sort the rest case-sensitive and remove duplicates
 	$(shell cat .spelling | awk 'NR<2{ print $0; next } { print $0 | "LC_COLLATE=C sort" }' | uniq | tee .spelling > /dev/null)
 
@@ -743,7 +743,7 @@ endif
 .PHONY: docs-lint
 docs-lint: /usr/local/bin/markdownlint docs/metrics.md
 	# lint docs
-	markdownlint docs --fix --ignore docs/fields.md --ignore docs/executor_swagger.md --ignore docs/cli --ignore docs/walk-through/the-structure-of-workflow-specs.md
+	markdownlint docs --fix --ignore docs/fields.md --ignore docs/executor_swagger.md --ignore docs/cli --ignore docs/walk-through/the-structure-of-workflow-specs.md --ignore docs/tested-kubernetes-versions.md
 
 /usr/local/bin/mkdocs:
 # update this in Nix when upgrading it here
@@ -762,6 +762,7 @@ docs: /usr/local/bin/mkdocs \
 	# check environment-variables.md contains all variables mentioned in the code
 	./hack/docs/check-env-doc.sh
 	# build the docs
+	./hack/docs/supported-versions.sh > docs/tested-kubernetes-versions.md
 	TZ=UTC mkdocs build --strict
 	# tell the user the fastest way to edit docs
 	@echo "ℹ️ If you want to preview your docs, open site/index.html. If you want to edit them with hot-reload, run 'make docs-serve' to start mkdocs on port 8000"

docs/releases.md

@@ -38,25 +38,14 @@ Otherwise, we typically release every two weeks:
 * Patch fixes for the current stable version.
 * The next RC, if we are currently in a release cycle.
 
-## Kubernetes Compatibility Matrix
+## Tested Versions
 
-| Argo Workflows \ Kubernetes | 1.29 | 1.30 | 1.31 | 1.32 |
-|-----------------------------|------|------|------|------|
-| **main**                    | `✓`  | `✓`  | `✓`  | `✓`  |
-| **3.6**                     | `✓`  | `✓`  | `✓`  | `?`  |
-| **3.5**                     | `✓`  | `✓`  | `?`  | `?`  |
-| **3.4**                     | `?`  | `?`  | `?`  | `?`  |
-
-* `✓` Fully supported versions.
-* `?` Due to breaking changes might not work. Also, we haven't thoroughly tested against this version.
-* `✕` Unsupported versions.
+--8<-- "docs/tested-kubernetes-versions.md"
 
 ### Notes on Compatibility
 
-Argo versions may be compatible with newer and older Kubernetes versions (indicated by `?`), but only three minor versions are tested unless otherwise noted.
+Argo versions may be compatible with newer and older Kubernetes versions, but only two minor versions are tested.
 
 Note that Kubernetes [is backward compatible with clients](https://github.com/kubernetes/client-go/tree/aa7909e7d7c0661792ba21b9e882f3cd6ad0ce53?tab=readme-ov-file#compatibility-client-go---kubernetes-clusters), so newer k8s versions are generally supported.
 The caveats with newer k8s versions are possible changes to experimental APIs and unused new features.
 Argo uses stable Kubernetes APIs such as Pods and ConfigMaps; see the Controller and Server RBAC of your [installation](installation.md) for a full list.
-
-The `main` branch is currently [tested on Kubernetes 1.29](https://github.com/argoproj/argo-workflows/blob/main/.github/workflows/ci-build.yaml#L228) and [1.32](https://github.com/argoproj/argo-workflows/blob/main/.github/workflows/ci-build.yaml#L263).

docs/tested-kubernetes-versions.md

@@ -0,0 +1 @@
+This page is populated for released Argo Workflows versions. Use the version selector to view this table for a specific version.

hack/docs/supported-versions.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+set -eu
+
+# Loosely based on https://github.com/argoproj/argo-cd/blob/5b79c34c72300e6e2e6336051ce6992f6d54011c/hack/update-supported-versions.sh
+
+# Extract major/minor versions from branch name, e.g. "release-3.5" will become:
+# release-
+# 3
+# 5
+mapfile -t branch_parts < <(git rev-parse --abbrev-ref ${1:-HEAD} | grep -Eo '.*release-|[0-9]')
+
+if [[ -z "${branch_parts[@]}" ]]; then
+  echo 'This page is populated for released Argo Workflows versions. Use the version selector to view this table for a specific version.'
+  exit
+fi
+
+echo "The following table shows the versions of Kubernetes that are tested with each version of Argo Workflows."
+echo
+echo "| Argo Workflows version | Kubernetes versions |"
+echo "|------------------------|---------------------|"
+
+for n in 0 1 2; do
+  new_version="${branch_parts[1]}.$((branch_parts[2] - n))"
+  new_branch="${branch_parts[0]}${new_version}"
+  k8s_versions=$(./hack/k8s-versions.sh "$new_branch" | paste -s | sed 's/\t/, /')
+  echo "|$new_version|$k8s_versions|"
+done

hack/k8s-versions.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -euo pipefail
+
+# For the given revision, extract the Kubernetes versions tested in the
+# corresponding e2e-tests CI workflow definition.
+# This would be cleaner if we extracted the version data to a separate file,
+# but this script is used to generate the "Tested versions" table, so it needs
+# to be compatible with old release branches.
+git grep -Eh 'INSTALL_K3S_VERSION=|install_k3s_version:' "${1:-HEAD}" -- .github/workflows/ci-build.yaml | grep -o 'v[0-9\.]\+' | sort -u

mkdocs.yml

@@ -55,6 +55,7 @@ validation:
 exclude_docs: |
   /proposals/
   /requirements.txt
+  /tested-kubernetes-versions.md
 
 nav:
   - Home: README.md