chore: refactor install script into a separate file

.github/workflows/lint.yml

@@ -73,7 +73,7 @@ jobs:
       - name: Verify shell scripts
         run: |
           echo "::add-matcher::.github/matcher-shellcheck.json"
-          shellcheck -f gcc -S warning hadolint.sh lib/*.sh test/*.sh
+          shellcheck -f gcc -S warning hadolint.sh install.sh lib/*.sh test/*.sh
   shfmt:
     name: Shfmt
     runs-on: ubuntu-22.04
@@ -84,4 +84,4 @@ jobs:
           version: "3.7.0"
         run: curl -Ls -o shfmt "https://github.com/mvdan/sh/releases/download/v${{ env.version }}/shfmt_v${{ env.version }}_linux_amd64" && chmod +x shfmt && sudo mv shfmt /usr/local/bin
       - name: Lint shell scripts
-        run: shfmt -i 2 -d hadolint.sh lib/*.sh test/*.sh
+        run: shfmt -i 2 -d hadolint.sh install.sh lib/*.sh test/*.sh

action.yml

@@ -45,37 +45,10 @@ runs:
   steps:
     - name: Download hadolint and make it available in path
       shell: bash
-      run: |
-        download_hadolint=false
-        # Check if hadolint exists
-        if [ ! -x "${{ github.action_path }}/bin/hadolint" ]; then
-          echo "::debug::Hadolint binary not found"
-          download_hadolint=true
-        else
-          echo "::debug::Hadolint binary exists"
-          version=$(${{ github.action_path }}/bin/hadolint --version 2>&1)
-          # Check if hadolint version can be retrieved
-          if [ $? -ne 0 ]; then
-            echo "::debug::Hadolint version cannot be retrieved"
-            download_hadolint=true
-          else
-            # Extract version number
-            version=$(echo "$version" | awk '{print $NF}')
-            if [ "$version" != "${{ inputs.version }}" ]; then
-              echo "::debug::Hadolint version does not match input version ($version != ${{ inputs.version }})"
-              download_hadolint=true
-            fi
-          fi
-        fi
-        # Download hadolint if necessary
-        if [ "$download_hadolint" = true ]; then
-          echo "::debug::Downloading Hadolint ${{ inputs.version }}"
-          mkdir -p ${{ github.action_path }}/bin
-          curl -L -s -o ${{ github.action_path }}/bin/hadolint \
-            "https://github.com/hadolint/hadolint/releases/download/v${{ inputs.version }}/hadolint-Linux-x86_64"
-          chmod +x ${{ github.action_path }}/bin/hadolint
-        fi
-        echo "${{ github.action_path }}/bin" >> "${GITHUB_PATH}"
+      env:
+        version: ${{ inputs.version }}
+      run: ${{ github.action_path }}/install.sh
+
     - name: Invoke hadolint.sh
       id: run
       shell: bash

install.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+CI=${GITHUB_ACTIONS:-}
+
+[[ -n "${DEBUG}" ]] && set -x
+set -euo pipefail
+shopt -s nullglob globstar
+
+[[ -z ${CI} ]] && echo "Will only run in Github Actions" && exit 1
+
+VERSION=${version:-}
+
+DOWNLOAD="false"
+# Check if hadolint exists
+if [ -x "$(command -v hadolint)" ]; then
+  INSTALLED_VERSION=$(hadolint --version | cut -d " " -f 4 2>&1)
+  echo "::debug::Found existing Hadolint version: ${INSTALLED_VERSION}"
+  if [ "${INSTALLED_VERSION}" != "${VERSION}" ]; then
+    echo "::debug::Hadolint version (${INSTALLED_VERSION}) does not match requested version (${VERSION})"
+    DOWNLOAD="true"
+  fi
+fi
+
+# Download hadolint if necessary
+if [ "${DOWNLOAD}" == "true" ]; then
+  echo "::debug::Downloading Hadolint ${VERSION}"
+  # https://github.com/actions/runner-images/issues/3727
+  # /usr/local/bin exists and is writable by any user
+  curl -L --fail -w "1" -o ./hadolint \
+    "https://github.com/hadolint/hadolint/releases/download/v${VERSION}/hadolint-Linux-x86_64" ||
+    echo "::error::Hadolint (version: ${VERSION}) could not be found. Exiting." && exit 1
+  chmod +x /usr/local/bin/hadolint
+fi