Add a shared OTP/Elixir toolchain preparation job

.github/dependabot.yml

@@ -1,7 +1,9 @@
 version: 2
 updates:
   - package-ecosystem: "github-actions"
-    directory: "/"
+    directories:
+      - "/"
+      - "/actions/*"
     schedule:
       interval: "weekly"
     cooldown:

.github/workflows/test-actions.yaml

@@ -0,0 +1,37 @@
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+---
+name: Test actions
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - actions/**
+      - .github/workflows/test-actions.yaml
+  pull_request:
+    paths:
+      - actions/**
+      - .github/workflows/test-actions.yaml
+
+permissions:
+  contents: read
+
+env:
+  BATS_VERSION: "1.14.0" # https://github.com/bats-core/bats-core/releases
+
+jobs:
+  test:
+    name: Lint and test action scripts
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Setup BATS
+        uses: bats-core/bats-action@77d6fb60505b4d0d1d73e48bd035b55074bbfb43 # v4.0.0
+        with:
+          bats-version: ${{ env.BATS_VERSION }}
+      - name: Run shellcheck
+        run: shellcheck actions/*/*.sh
+      - name: Run bats tests
+        run: bats actions/*/tests/*.bats

.tool-versions

@@ -0,0 +1,2 @@
+bats 1.14.0
+shellcheck 0.10.0

actions/elixir-toolchain/action.yaml

@@ -0,0 +1,50 @@
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+---
+name: Compute OTP/Elixir toolchain
+description: >-
+  Read Erlang/OTP and Elixir from `.tool-versions` in the working directory,
+  and build the toolchain list for an Elixir job matrix.
+
+inputs:
+  elixir-bc:
+    description: Elixir version of the backward compatibility toolchain. Required when `bc-enabled` is "true".
+    required: false
+    default: ""
+  erlang-bc:
+    description: Erlang/OTP version of the backward compatibility toolchain. Required when `bc-enabled` is "true".
+    required: false
+    default: ""
+  bc-enabled:
+    description: Set to "true" to add the backward compatibility toolchain.
+    required: false
+    default: "false"
+
+outputs:
+  ELIXIR_DEV:
+    description: Elixir version from `.tool-versions`.
+    value: ${{ steps.compute.outputs.ELIXIR_DEV }}
+  ERLANG_DEV:
+    description: Erlang/OTP version from `.tool-versions`.
+    value: ${{ steps.compute.outputs.ERLANG_DEV }}
+  TOOLCHAINS:
+    description: JSON array of `{elixir, otp}` objects, the backward compatibility toolchain first when enabled.
+    value: ${{ steps.compute.outputs.TOOLCHAINS }}
+
+runs:
+  using: composite
+  steps:
+    - name: Read .tool-versions
+      id: parse
+      uses: endorama/asdf-parse-tool-versions@115a5df5884438dfd08a3a21e9c9efdf06dd907e # v1.7.0
+    - name: Compute toolchain
+      id: compute
+      shell: bash
+      env:
+        ELIXIR_VERSION: ${{ fromJson(steps.parse.outputs.tools).elixir }}
+        ERLANG_VERSION: ${{ fromJson(steps.parse.outputs.tools).erlang }}
+        ELIXIR_BC: ${{ inputs.elixir-bc }}
+        ERLANG_BC: ${{ inputs.erlang-bc }}
+        BC_ENABLED: ${{ inputs.bc-enabled }}
+      run: '"${{ github.action_path }}/compute-toolchain.sh"'

actions/elixir-toolchain/compute-toolchain.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+set -euo pipefail
+
+if [[ -z "${ELIXIR_VERSION:-}" || -z "${ERLANG_VERSION:-}" ]]; then
+  echo "::error::.tool-versions must define both elixir and erlang"
+  exit 1
+fi
+if [[ "${BC_ENABLED:-}" == "true" && ( -z "${ELIXIR_BC:-}" || -z "${ERLANG_BC:-}" ) ]]; then
+  echo "::error::bc-enabled requires elixir-bc and erlang-bc"
+  exit 1
+fi
+TOOLCHAINS=$(jq -cn \
+  --arg elixir_bc "${ELIXIR_BC:-}" --arg otp_bc "${ERLANG_BC:-}" \
+  --arg elixir_dev "$ELIXIR_VERSION" --arg otp_dev "$ERLANG_VERSION" \
+  --arg bc_enabled "${BC_ENABLED:-}" '
+  [
+    {elixir: $elixir_bc,  otp: $otp_bc},
+    {elixir: $elixir_dev, otp: $otp_dev}
+  ]
+  | if $bc_enabled == "true" then . else .[1:] end')
+{
+  echo "ELIXIR_DEV=$ELIXIR_VERSION"
+  echo "ERLANG_DEV=$ERLANG_VERSION"
+  echo "TOOLCHAINS=$TOOLCHAINS"
+} >> "$GITHUB_OUTPUT"

actions/elixir-toolchain/tests/compute-toolchain.bats

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+#!/usr/bin/env bats
+
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+setup() {
+  SCRIPT="$(cd "$(dirname "$BATS_TEST_FILENAME")/.." && pwd)/compute-toolchain.sh"
+  export GITHUB_OUTPUT="$BATS_TEST_TMPDIR/github_output"
+  : > "$GITHUB_OUTPUT"
+  unset ELIXIR_BC ERLANG_BC BC_ENABLED
+  export ELIXIR_VERSION=1.19.5-otp-27
+  export ERLANG_VERSION=27.3.4.11
+}
+
+DEV='{"elixir":"1.19.5-otp-27","otp":"27.3.4.11"}'
+BC='{"elixir":"1.15.7-otp-26","otp":"26.2.1"}'
+
+set_bc() {
+  export ELIXIR_BC=1.15.7-otp-26
+  export ERLANG_BC=26.2.1
+}
+
+@test "script is executable" {
+  [ -x "$SCRIPT" ]
+}
+
+@test "no BC variables set: dev toolchain only" {
+  run "$SCRIPT"
+  [ "$status" -eq 0 ]
+  [ "$(cat "$GITHUB_OUTPUT")" = "ELIXIR_DEV=1.19.5-otp-27
+ERLANG_DEV=27.3.4.11
+TOOLCHAINS=[$DEV]" ]
+}
+
+@test "BC enabled: BC toolchain first, then dev" {
+  set_bc
+  export BC_ENABLED=true
+  run "$SCRIPT"
+  [ "$status" -eq 0 ]
+  grep -qxF "TOOLCHAINS=[$BC,$DEV]" "$GITHUB_OUTPUT"
+}
+
+@test "BC versions set, BC disabled: dev toolchain only" {
+  set_bc
+  export BC_ENABLED=false
+  run "$SCRIPT"
+  [ "$status" -eq 0 ]
+  grep -qxF "TOOLCHAINS=[$DEV]" "$GITHUB_OUTPUT"
+}
+
+@test "BC enabled without elixir-bc: fails" {
+  set_bc
+  unset ELIXIR_BC
+  export BC_ENABLED=true
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+  [ "$output" = "::error::bc-enabled requires elixir-bc and erlang-bc" ]
+  [ ! -s "$GITHUB_OUTPUT" ]
+}
+
+@test "BC enabled without erlang-bc: fails" {
+  set_bc
+  export ERLANG_BC=""
+  export BC_ENABLED=true
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+  [ "$output" = "::error::bc-enabled requires elixir-bc and erlang-bc" ]
+}
+
+@test "no elixir in .tool-versions: fails" {
+  unset ELIXIR_VERSION
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+  [ "$output" = "::error::.tool-versions must define both elixir and erlang" ]
+}
+
+@test "no erlang in .tool-versions: fails" {
+  export ERLANG_VERSION=""
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+  [ "$output" = "::error::.tool-versions must define both elixir and erlang" ]
+}

actions/setup-elixir/action.yaml

@@ -0,0 +1,73 @@
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+---
+name: Set up Elixir and restore dependencies
+description: >-
+  Install Erlang/OTP and Elixir, then restore the Elixir dependency cache.
+  With build-deps, also build the dependencies on a cache miss. The jobs that
+  build the dependencies and the jobs that use them share this cache key
+  format. MIX_ENV must be set in the job environment.
+
+inputs:
+  otp-version:
+    description: Erlang/OTP version. It is also part of the cache key.
+    required: true
+  elixir-version:
+    description: Elixir version. It is also part of the cache key.
+    required: true
+  cache-key-suffix:
+    description: Extra cache key segment, added after the Elixir version. Empty adds nothing.
+    required: false
+    default: ""
+  setup-beam:
+    description: Set to "false" to restore the cache without installing Erlang/OTP and Elixir.
+    required: false
+    default: "true"
+  build-deps:
+    description: >-
+      Set to "true" to fetch and compile the dependencies, and to build the
+      Dialyzer PLT when MIX_ENV is not prod, on a cache miss. The cache saves
+      the result at the end of the job.
+    required: false
+    default: "false"
+
+outputs:
+  cache-hit:
+    description: '"true" when the cache key matched exactly.'
+    value: ${{ steps.cache.outputs.cache-hit }}
+
+runs:
+  using: composite
+  steps:
+    - name: Check MIX_ENV
+      shell: bash
+      run: '"${{ github.action_path }}/check-mix-env.sh"'
+    - name: Set up Erlang/OTP and Elixir
+      if: inputs.setup-beam == 'true'
+      uses: erlef/setup-beam@54075bcc5e249e4758d363f27d099f55d843f124 # v1.24.1
+      with:
+        otp-version: ${{ inputs.otp-version }}
+        elixir-version: ${{ inputs.elixir-version }}
+    - name: Restore Elixir dependencies
+      id: cache
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: |
+          deps
+          _build/${{ env.MIX_ENV }}
+          priv/plts
+        key: erlang-${{ inputs.otp-version }}-elixir-${{ inputs.elixir-version }}${{ inputs.cache-key-suffix != '' && format('-{0}', inputs.cache-key-suffix) || '' }}-${{ hashFiles('mix.lock') }}-${{ env.MIX_ENV }}
+    - name: Install dependencies
+      if: inputs.build-deps == 'true' && steps.cache.outputs.cache-hit != 'true'
+      shell: bash
+      run: |
+        mkdir -p priv/plts
+        mix local.rebar --force
+        mix local.hex --force
+        mix deps.get
+        mix deps.compile --warnings-as-errors
+    - name: Build Dialyzer PLT
+      if: inputs.build-deps == 'true' && steps.cache.outputs.cache-hit != 'true' && env.MIX_ENV != 'prod'
+      shell: bash
+      run: mix dialyzer --plt

actions/setup-elixir/check-mix-env.sh

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+#!/usr/bin/env bash
+
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+set -euo pipefail
+
+if [[ -z "${MIX_ENV:-}" ]]; then
+  echo "::error::MIX_ENV must be set in the job environment"
+  exit 1
+fi

actions/setup-elixir/tests/check-mix-env.bats

@@ -0,0 +1,32 @@
+#!/usr/bin/env bats
+
+# SPDX-FileCopyrightText: SUSE LLC
+# SPDX-License-Identifier: Apache-2.0
+
+setup() {
+  SCRIPT="$(cd "$(dirname "$BATS_TEST_FILENAME")/.." && pwd)/check-mix-env.sh"
+  unset MIX_ENV
+}
+
+@test "script is executable" {
+  [ -x "$SCRIPT" ]
+}
+
+@test "MIX_ENV set: succeeds" {
+  export MIX_ENV=test
+  run "$SCRIPT"
+  [ "$status" -eq 0 ]
+  [ -z "$output" ]
+}
+
+@test "MIX_ENV unset: fails" {
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+  [ "$output" = "::error::MIX_ENV must be set in the job environment" ]
+}
+
+@test "MIX_ENV empty: fails" {
+  export MIX_ENV=""
+  run "$SCRIPT"
+  [ "$status" -eq 1 ]
+}