chore: make it possible to install older versions of the heroku cli

.github/workflows/self-test.yml

@@ -0,0 +1,31 @@
+on:
+  pull_request:
+    branches: ['*']
+  push:
+    branches: ['main']
+  schedule:
+  - cron: "18 18 * * 1"
+
+jobs:
+  selfcheck:
+    name: Test Action
+    strategy:
+      matrix:
+        runner: [ubuntu-22.04, ubuntu-24.04, ubuntu-latest]
+        version: [latest, 9.5.1, 10.0.0]
+    runs-on: ${{ matrix.runner }}
+    steps:
+      # To use this repository's private action,
+      # you must check out the repository
+      - name: Checkout
+        uses: actions/checkout@v4
+      - uses: ./
+        with:
+          version: ${{matrix.version}}
+  lint-with-pre-commit:
+    runs-on: ubuntu-24.04
+    name: Lint with pre-commit
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+    - uses: instrumentl/pre-commit-action@v4

.pre-commit-config.yaml

@@ -0,0 +1,16 @@
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v5.0.0
+  hooks:
+  - id: trailing-whitespace
+  - id: end-of-file-fixer
+  - id: check-yaml
+  - id: check-added-large-files
+  - id: fix-byte-order-marker
+  - id: check-json
+  - id: check-merge-conflict
+- repo: https://github.com/Mateusz-Grzelinski/actionlint-py
+  rev: v1.7.4.20
+  hooks:
+  - id: actionlint
+    additional_dependencies: [ pyflakes>=3.0.1, shellcheck-py>=0.9.0.5 ]

action.yml

@@ -1,14 +1,63 @@
 name: 'Set up Heroku'
 description: 'Set up the Heroku CLI'
+inputs:
+  version:
+    description: "Version to install"
+    required: true
+    default: "latest"
 runs:
   using: "composite"
   steps:
-  - name: "Ensure GPG installed"
+  - name: "Ensure dependencies are installed"
     shell: bash
-    run: "if ! command -v gpg; then apt-get install --no-install-recommends gnupg2 ; fi"
+    run: |
+      if ! command -v gpg; then sudo -n apt-get install --no-install-recommends gnupg2 ; fi
+      if ! command -v curl; then sudo -n apt-get install --no-install-recommends curl ; fi
+      if ! command -v jq; then sudo -n apt-get install --no-install-recommends jq ; fi
   - name: "Install Heroku CLI"
     shell: bash
-    run: "curl -f https://cli-assets.heroku.com/install-ubuntu.sh | sh"
+    env:
+      version: ${{ inputs.version }}
+    run: |
+      set -euo pipefail
+
+      wd="$(mktemp -d)"
+      on_exit() {
+        status=$?
+        [[ -n "$wd" ]] && rm -rf "$wd"
+        exit $status
+      }
+
+      trap on_exit EXIT INT TERM
+      raw_machine="$(uname -m)"
+      if [[ "$raw_machine" = "aarch64" ]]; then
+        machine="arm"
+      elif [[ "$raw_machine" = "x86_64" ]]; then
+        machine="x64"
+      else
+        echo >&2 "Unhandled machine type $raw_machine"
+        exit 1
+      fi
+
+      curl -fqs -o "$wd/versions.json" "https://cli-assets.heroku.com/versions/heroku-linux-${machine}-tar-gz.json"
+      if [[ "$version" = "latest" ]]; then
+        url="https://cli-assets.heroku.com/channels/stable/heroku-linux-${machine}.tar.gz"
+      else
+        url="$(jq -cr '.["'"${version}"'"]' < "$wd/versions.json")"
+      fi
+      if [[ -z "$url" ]] || [[ "$url" = "null" ]]; then
+        echo >&2 "Could not find download for ${version} for ${machine}"
+        exit 1
+      fi
+      curl -o "$wd/heroku.tar.gz" -sq "$url"
+
+      sudo -n rm -rf /usr/local/lib/heroku
+      sudo -n mkdir -p /usr/local/lib/heroku
+      sudo -n tar -C /usr/local/lib -xpzf "$wd/heroku.tar.gz"
+      sudo -n rm -f /usr/local/bin/heroku
+      sudo -n ln -s /usr/local/lib/heroku/bin/heroku /usr/local/bin/heroku
+
+      /usr/local/lib/heroku/bin/node -v || sudo -n rm /usr/local/lib/heroku/bin/node
   - name: "Test that it runs correctly"
     run: "heroku version"
     shell: bash