[eclipse-wakaamaGH-585] ci: Integrate gitlint

This is a fairly default configuration, which, among other stuff,
checks for the subject line being 72 or less characters as required by
the Eclipse project handbook.

Non-default rules:
- Enforce at least 20 characters in the commit body
- Disallow the word "fixup" in the title messages. Intended to prevent
  accidents like d31d026.

In case any of those rules get in the way, use the "gitlint-ignore" tag
in the commit message to suppress gitlint findings for this specific
commit. To configure a rule permanently, adapt .gitlint.

The GitHub Action runs only on PRs, not after each push. The idea is to
prevent annoyance when working on code, using WIP or other non-compliant
commit messages.

.github/workflows/compliance.yaml

@@ -0,0 +1,23 @@
+name: Compliance
+
+on: pull_request
+
+jobs:
+  check-gitlint:
+    name: Run gitlint
+    runs-on: ubuntu-20.04
+
+    steps:
+    - name: Checkout code including full history
+      uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+
+    - name: Install gitlint
+      run: |
+        pip3 install gitlint
+
+    - name: Check commits with checkpatch
+      run: |
+        git branch -a
+        tools/ci/run_ci.sh --branch-target origin/${{ github.base_ref }} --run-gitlint

.gitlint

@@ -0,0 +1,12 @@
+[general]
+ignore-fixup-commits=false
+
+[title-must-not-contain-word]
+words=wip,fixup
+
+# Enforce at least 20 characters (default value) in every commit body
+[body-min-length]
+
+# Tags do not count towards the body length
+[ignore-body-lines]
+regex=^Signed-off-by

tools/ci/run_ci.sh

@@ -20,6 +20,8 @@ readonly REPO_ROOT_DIR="${PWD}"
 readonly SCRIPT_NAME="$(basename "$0")"
 
 CMAKE_ARGS="-DCMAKE_BUILD_TYPE=RelWithDebInfo"
+OPT_BRANCH_SOURCE=
+OPT_BRANCH_TARGET=master
 OPT_C_EXTENSIONS=""
 OPT_C_STANDARD=""
 OPT_SANITIZER=""
@@ -30,13 +32,18 @@ OPT_VERBOSE=0
 OPT_WRAPPER_CMD=""
 RUN_BUILD=0
 RUN_CLEAN=0
+RUN_GITLINT=0
 RUN_TESTS=0
 
 HELP_MSG="usage: ${SCRIPT_NAME} <OPTIONS>...
 Runs build and test steps in CI.
 Select steps to execute with --run- options
 
 Options:
+  --branch-source BRANCH    Source branch for MRs
+                            (default: current branch)
+  --branch-target BRANCH    Target branch for MRs
+                            (default: $OPT_BRANCH_TARGET)
   --c-extensions ENABLE     Whether to allow compiler extensions. Defaults to
                             ON.
                             (ENABLE: ON or OFF)
@@ -56,6 +63,7 @@ Options:
   -h, --help                Display this help and exit
 
 Available steps (executed by --all):
+  --run-gitlint            Check git commits with gitlint
   --run-clean              Remove all build artifacts
   --run-build              Build all targets
   --run-tests              Build and execute tests
@@ -72,6 +80,12 @@ function run_clean() {
   rm -rf build-wakaama
 }
 
+function run_gitlint() {
+  commits="${OPT_BRANCH_TARGET}...${OPT_BRANCH_SOURCE}"
+
+  gitlint --commits "${commits}"
+}
+
 function run_build() {
   # Existing directory needed by SonarQube build-wrapper
   mkdir -p build-wakaama
@@ -135,11 +149,14 @@ fi
 
 if ! PARSED_OPTS=$(getopt -o vah \
                           -l all \
+                          -l branch-source: \
+                          -l branch-target: \
                           -l c-extensions: \
                           -l c-standard: \
                           -l help \
                           -l run-build \
                           -l run-clean \
+                          -l run-gitlint \
                           -l run-tests \
                           -l sanitizer: \
                           -l scan-build: \
@@ -155,6 +172,14 @@ eval set -- "${PARSED_OPTS}"
 
 while true; do
   case "$1" in
+    --branch-source)
+      OPT_BRANCH_SOURCE=$2
+      shift 2
+      ;;
+    --branch-target)
+      OPT_BRANCH_TARGET=$2
+      shift 2
+      ;;
     --c-extensions)
       OPT_C_EXTENSIONS=$2
       shift 2
@@ -171,6 +196,10 @@ while true; do
       RUN_BUILD=1
       shift 1
       ;;
+    --run-gitlint)
+      RUN_GITLINT=1
+      shift
+      ;;
     --run-tests)
       RUN_TESTS=1
       shift
@@ -205,6 +234,7 @@ while true; do
       ;;
     -a|--all)
       RUN_CLEAN=1
+      RUN_GITLINT=1
       RUN_BUILD=1
       RUN_TESTS=1
       shift
@@ -262,6 +292,10 @@ fi
 
 # Run Steps
 
+if [[ $RUN_GITLINT == 1 ]]; then
+    run_gitlint
+fi
+
 if [ "${RUN_CLEAN}" -eq 1 ]; then
   run_clean
 fi