aptfile support

README.md

@@ -32,7 +32,7 @@ There are three kinds of version labels you can use.
 
 ### Inputs
 
-- `packages` - Space delimited list of packages to install.
+- `packages` - Space delimited list of packages to install. If not provided, packages will be read from `Aptfile` at the repository root if it exists. Packages from both the input and `Aptfile` will be merged if both are provided.
 - `version` - Version of cache to load. Each version will have its own cache. Note, all characters except spaces are allowed.
 - `execute_install_scripts` - Execute Debian package pre and post install script upon restore. See [Caveats / Non-file Dependencies](#non-file-dependencies) for more information.
 - `empty_packages_behavior` - Desired behavior when the given `packages` is empty. `'error'` (default), `'warn'` or `'ignore'`.
@@ -121,6 +121,49 @@ install_from_multiple_repos:
         version: 1.0
 ```
 
+### Using Aptfile
+
+You can also use an `Aptfile` at your repository root to specify packages. The action will automatically read and cache packages from the `Aptfile` if it exists. Comments (lines starting with `#`) and inline comments are supported.
+
+**Example Aptfile:**
+```
+# Core development tools
+cmake
+autoconf
+git
+gh
+
+# Build dependencies
+build-essential
+libssl-dev
+python3-dev
+```
+
+**Example workflow using Aptfile:**
+```yaml
+name: Build with Aptfile
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: awalsh128/cache-apt-pkgs-action@latest
+        with:
+          version: v1
+          # packages input can be omitted if using Aptfile only
+      - name: Build
+        run: make
+```
+
+You can also combine packages from both the input and `Aptfile`:
+```yaml
+- uses: awalsh128/cache-apt-pkgs-action@latest
+  with:
+    version: v1
+    packages: protobuf-compiler sd  # Additional packages beyond Aptfile
+```
+
 ## Caveats
 
 ### Non-file Dependencies

action.yml

@@ -7,8 +7,8 @@ branding:
 
 inputs:
   packages:
-    description: 'Space delimited list of packages to install. Version can be specified optionally using APT command syntax of <name>=<version> (e.g. xdot=1.2-2).'
-    required: true
+    description: 'Space delimited list of packages to install. Version can be specified optionally using APT command syntax of <name>=<version> (e.g. xdot=1.2-2). If not provided, packages will be read from Aptfile at repository root if it exists.'
+    required: false
     default: ''
   version:
     description: 'Version of cache to load. Each version will have its own cache. Note, all characters except spaces are allowed.'

lib.sh

@@ -157,6 +157,31 @@ function validate_bool {
   fi
 }
 
+###############################################################################
+# Parses an Aptfile and extracts package names.
+# Arguments:
+#   File path to the Aptfile.
+# Returns:
+#   Space delimited list of package names (comments and empty lines removed).
+###############################################################################
+function parse_aptfile {
+  local aptfile_path="${1}"
+  if test ! -f "${aptfile_path}"; then
+    echo ""
+    return
+  fi
+
+  # Remove lines starting with #, remove inline comments (everything after #),
+  # trim whitespace, remove empty lines, and join with spaces
+  grep -v '^[[:space:]]*#' "${aptfile_path}" \
+    | sed 's/#.*$//' \
+    | sed 's/^[[:space:]]*//;s/[[:space:]]*$//' \
+    | grep -v '^$' \
+    | tr '\n' ' ' \
+    | sed 's/[[:space:]]\+/ /g' \
+    | sed 's/^[[:space:]]*//;s/[[:space:]]*$//'
+}
+
 ###############################################################################
 # Writes the manifest to a specified file.
 # Arguments:

post_cache_action.sh

@@ -29,7 +29,22 @@ test "${debug}" = "true" && set -x
 add_repository="${6}"
 
 # List of the packages to use.
-packages="${@:7}"
+# Try to read from saved file first (includes Aptfile packages), fallback to input
+packages_filepath="${cache_dir}/packages.txt"
+if test -f "${packages_filepath}"; then
+  packages="$(cat "${packages_filepath}")"
+  # Check if packages.txt is empty or contains only whitespace
+  if test -z "${packages}"; then
+    log "packages.txt exists but is empty, falling back to input packages"
+    packages="${@:7}"
+  else
+    log "Using packages from cache directory (includes Aptfile if present)"
+  fi
+else
+  # Fallback to input packages (for backwards compatibility)
+  packages="${@:7}"
+  log "Using packages from input (Aptfile not processed)"
+fi
 
 if test "${cache_hit}" = "true"; then
   ${script_dir}/restore_pkgs.sh "${cache_dir}" "${cache_restore_root}" "${execute_install_scripts}" "${debug}"

pre_cache_action.sh

@@ -30,39 +30,71 @@ add_repository="${5}"
 # List of the packages to use.
 input_packages="${@:6}"
 
-# Trim commas, excess spaces, and sort.
-log "Normalizing package list..."
-packages="$(get_normalized_package_list "${input_packages}")"
-log "done"
+# Check for Aptfile at repository root and merge with input packages
+aptfile_path="${GITHUB_WORKSPACE:-.}/Aptfile"
+aptfile_packages=""
+if test -n "${GITHUB_WORKSPACE}" && test -f "${aptfile_path}"; then
+  log "Found Aptfile at ${aptfile_path}, parsing packages..."
+  aptfile_packages="$(parse_aptfile "${aptfile_path}")"
+  if test -n "${aptfile_packages}"; then
+    log "Parsed $(echo "${aptfile_packages}" | wc -w) package(s) from Aptfile"
+  else
+    log "Aptfile is empty or contains only comments"
+  fi
+elif test -z "${GITHUB_WORKSPACE}"; then
+  log "GITHUB_WORKSPACE not set, skipping Aptfile check"
+else
+  log "No Aptfile found at ${aptfile_path}"
+fi
+
+# Merge input packages with Aptfile packages
+if test -n "${input_packages}" && test -n "${aptfile_packages}"; then
+  combined_packages="${input_packages} ${aptfile_packages}"
+  log "Merging packages from input and Aptfile..."
+elif test -n "${aptfile_packages}"; then
+  combined_packages="${aptfile_packages}"
+  log "Using packages from Aptfile only..."
+elif test -n "${input_packages}"; then
+  combined_packages="${input_packages}"
+  log "Using packages from input only..."
+else
+  combined_packages=""
+fi
 
 # Create cache directory so artifacts can be saved.
 mkdir -p ${cache_dir}
 
-log "Validating action arguments (version='${version}', packages='${packages}')...";
+log "Validating action arguments (version='${version}', packages='${combined_packages}')...";
 if grep -q " " <<< "${version}"; then
   log "aborted" 
   log "Version value '${version}' cannot contain spaces." >&2
   exit 2
 fi
 
-# Is length of string zero?
-if test -z "${packages}"; then
+# Check if packages are empty before calling get_normalized_package_list
+# (which would error if called with empty input)
+if test -z "${combined_packages}"; then
   case "$EMPTY_PACKAGES_BEHAVIOR" in
     ignore)
       exit 0
       ;;
     warn)
-      echo "::warning::Packages argument is empty."
+      echo "::warning::Packages argument is empty. Please provide packages via the 'packages' input or create an Aptfile at the repository root."
       exit 0
       ;;
     *)
       log "aborted"
-      log "Packages argument is empty." >&2
+      log "Packages argument cannot be empty. Please provide packages via the 'packages' input or create an Aptfile at the repository root." >&2
       exit 3
       ;;
   esac
 fi
 
+# Trim commas, excess spaces, and sort.
+log "Normalizing package list..."
+packages="$(get_normalized_package_list "${combined_packages}")"
+log "done"
+
 validate_bool "${execute_install_scripts}" execute_install_scripts 4
 
 # Basic validation for repository parameter
@@ -119,5 +151,14 @@ log "- Value hashed as '${key}'."
 log "done"
 
 key_filepath="${cache_dir}/cache_key.md5"
-echo ${key} > ${key_filepath}
+echo "${key}" > "${key_filepath}"
 log "Hash value written to ${key_filepath}"
+
+# Save normalized packages to file so post_cache_action.sh can use them
+packages_filepath="${cache_dir}/packages.txt"
+echo "${packages}" > "${packages_filepath}"
+if test ! -f "${packages_filepath}"; then
+  log "Failed to write packages.txt" >&2
+  exit 4
+fi
+log "Normalized packages saved to ${packages_filepath}"