Add shell script linter

This repo is heavy on shell scripts. Linting could be a nice addition.

Therefore this commit adds:

- linting via shellcheck
- an example .shellcheckrc file for global shellcheck control
- a shellcheck.sh helper script to run it on specific shell files
- a .shellcheck configuration for the helper script

Author: lloeki

.github/workflows/lint.yml

@@ -0,0 +1,16 @@
+name: Lint
+on:
+  push:
+    branches:
+    - '**'
+
+jobs:
+  shellcheck:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Install shellcheck'
+        run: sudo apt-get install -y shellcheck
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: 'Run shellcheck'
+        run: ./utils/scripts/shellcheck.sh

.shellcheck

@@ -0,0 +1,38 @@
+# These files have not been fixed yet
+TODO=(
+  utils/scripts/load-binary.sh
+  utils/scripts/install_mitm_certificate.sh
+  utils/scripts/update_dashboard_CI_visibility.sh
+  utils/scripts/slack/report.sh
+  utils/scripts/docker_base_image.sh
+  utils/scripts/upload_results_CI_visibility.sh
+  utils/build/docker/postgres-init-db.sh
+  utils/build/docker/nodejs/app.sh
+  utils/build/docker/nodejs/install_ddtrace.sh
+  utils/build/docker/set-uds-transport.sh
+  utils/build/docker/python/flask/app.sh
+  utils/build/docker/python/install_ddtrace.sh
+  utils/build/docker/python/django/app.sh
+  utils/build/docker/golang/app.sh
+  utils/build/docker/golang/install_ddtrace.sh
+  utils/build/docker/weblog-cmd.sh
+  utils/build/docker/java/app.sh
+  utils/build/docker/java/install_ddtrace.sh
+  utils/build/docker/java/spring-boot/app.sh
+  utils/build/docker/php/apache-mod/build.sh
+  utils/build/docker/php/apache-mod/entrypoint.sh
+  utils/build/docker/php/php-fpm/build.sh
+  utils/build/docker/php/php-fpm/entrypoint.sh
+  utils/build/docker/php/common/install_ddtrace.sh
+  utils/build/docker/dotnet/app.sh
+  utils/build/docker/dotnet/install_ddtrace.sh
+  utils/build/docker/cpp/install_ddprof.sh
+  utils/build/docker/cpp/nginx/app.sh
+  utils/build/docker/cpp/nginx/install_ddtrace.sh
+  utils/build/docker/ruby/install_ddtrace.sh
+  utils/build/build.sh
+  utils/interfaces/schemas/serve.sh
+  build.sh
+  format.sh
+  run.sh
+)

.shellcheckrc

@@ -0,0 +1,5 @@
+# Add globally disabled checks here, e.g:
+#
+# SC1091: Not following <file>
+# https://github.com/koalaman/shellcheck/wiki/SC1091
+# disable=SC1091

utils/scripts/shellcheck.sh

@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+
+set -e
+set -u
+set -o pipefail
+
+function has() {
+    local needle="${1}"
+    shift
+
+    local e
+    for e; do [[ "${e}" == "${needle}" ]] && return 0; done
+
+    return 1
+}
+
+function walk() {
+    local candidate="${1}"
+    shift
+
+    local names=( "${@}" )
+
+    while [[ -n "${candidate}" ]]; do
+        for file in "${names[@]}"; do
+            if [[ -e "${candidate}/${file}" ]]; then
+                echo "${candidate}"
+                return
+            fi
+        done
+        candidate="${candidate%/*}"
+    done
+    return 1
+}
+
+function lint() {
+    local files=()
+
+    while read -r f; do
+        if has "${f}" "${TODO[@]}"; then
+            continue
+        fi
+
+        files+=("$f")
+    done < <( find utils -name '*.sh'; ls -1 -- *.sh )
+
+    shellcheck "${files[@]}"
+}
+
+function root() {
+    walk "${PWD}" '.shellcheck' '.git'
+}
+
+function load_config() {
+    # defaults
+    TODO=()
+
+    local root
+    root="$(root)"
+
+    local config="${root}/.shellcheck"
+
+    if [[ -f "${config}" ]]; then
+        # shellcheck disable=SC1090
+        source "${config}"
+    fi
+}
+
+function main() {
+    load_config
+    lint
+}
+
+if [[ "${0}" == "${BASH_SOURCE[0]}" ]]; then
+    main "${@}"
+fi