fix: Have download:false respect binary_folder

Author: JanSF

README.md

@@ -449,19 +449,19 @@ steps:
           wait: true
 ```
 
-### `download_folder` (optional)
+### `binary_folder` (optional)
 
 Default: `BUILDKITE_PLUGINS_PATH`
 
-This is the filesystem folder where the Go binary will be download to.
+This is the filesystem folder where the Go binary will be kept.
 
 ## Example
 ```yaml
 steps:
   - label: "Triggering pipelines"
     plugins:
       - monorepo-diff#v1.8.0:
-          download_folder: "/var/buildkite-agent"
+          binary_folder: "/var/buildkite-agent"
           watch:
             - path: "bar-service/"
               config:

hooks/command

@@ -17,7 +17,7 @@ err() {
   exit 1
 }
 
-executable_dir="${BUILDKITE_PLUGIN_MONOREPO_DIFF_DOWNLOAD_FOLDER:-${BUILDKITE_PLUGINS_PATH}}"
+executable_dir="${BUILDKITE_PLUGIN_MONOREPO_DIFF_BINARY_FOLDER:-${BUILDKITE_PLUGINS_PATH}}"
 
 # Default to current directory if not set
 if [[ -z "${executable_dir}" ||  ${BUILDKITE_PLUGIN_MONOREPO_DIFF_BUILDKITE_PLUGIN_TEST_MODE:-false} == "true" ]]; then
@@ -34,7 +34,7 @@ if [[ ! -w "${executable_dir}" ]]; then
   err "Directory not writable: ${executable_dir}"
 fi
 
-executable="${executable_dir}/monorepo-diff-buildkite-plugin"
+executable="${executable_dir%/}/monorepo-diff-buildkite-plugin"
 executable_version_file="${executable}.version"
 
 check_cmd() {
@@ -204,8 +204,17 @@ download_binary_and_run() {
 run_preinstalled_binary() {
   local _executable="monorepo-diff-buildkite-plugin"
 
-  if ! check_cmd "$_executable"; then
-    err "Binary '$_executable' not found in PATH. Please install it or set download: true"
+  # Check if BINARY_FOLDER is defined and use that path
+  if [[ -n "${BUILDKITE_PLUGIN_MONOREPO_DIFF_BINARY_FOLDER:-}" ]]; then
+    _executable="${BUILDKITE_PLUGIN_MONOREPO_DIFF_BINARY_FOLDER%/}/${_executable}"
+    if ! check_cmd "$_executable"; then
+      err "Binary not found or not executable in BINARY_FOLDER: $_executable"
+    fi
+  else
+    # Fall back to PATH lookup
+    if ! check_cmd "$_executable"; then
+      err "Binary '$_executable' not found in PATH. Please install it or set download: true"
+    fi
   fi
 
   ${_executable} "$@"

plugin.yml

@@ -15,7 +15,7 @@ configuration:
       type: boolean
     env:
       type: array
-    download_folder:
+    binary_folder:
       type: string
     notify:
       type: [array]

tests/command.bats

@@ -9,6 +9,7 @@ setup() {
   export BUILDKITE_PLUGIN_MONOREPO_DIFF_BUILDKITE_PLUGIN_TEST_MODE=true
   # Set a minimal plugin config (only used by Go binary, not the bash hook's download logic)
   export BUILDKITE_PLUGINS='[{"monorepo-diff": {}}]'
+  export BUILDKITE_PLUGINS_PATH='/etc/buildkite-agent/plugins'
 
   # Create a mock binary in the current directory for download mode tests
   cat > "$PWD/monorepo-diff-buildkite-plugin" << 'MOCKBIN'
@@ -104,8 +105,8 @@ teardown() {
   export BUILDKITE_PLUGINS='[{"github.com/buildkite-plugins/monorepo-diff-buildkite-plugin#v1.0.0": {}}]'
 
   # Remove mock binary so it actually needs to download
-  rm -f "$PWD/monorepo-diff-buildkite-plugin"
-  rm -f "$PWD/monorepo-diff-buildkite-plugin.version"
+  rm -f "$BUILDKITE_PLUGINS_PATH/monorepo-diff-buildkite-plugin"
+  rm -f "$BUILDKITE_PLUGINS_PATH/monorepo-diff-buildkite-plugin.version"
 
   # Stub curl: fail twice on download, then succeed and create executable
   stub curl \
@@ -129,9 +130,10 @@ teardown() {
   export BUILDKITE_PLUGIN_MONOREPO_DIFF_BUILDKITE_PLUGIN_TEST_MODE=false
   # Use pinned version to skip get_latest_version API call
   export BUILDKITE_PLUGINS='[{"github.com/buildkite-plugins/monorepo-diff-buildkite-plugin#v1.0.0": {}}]'
-  
+
   # Remove mock binary so it actually needs to download
-  rm -f "$PWD/monorepo-diff-buildkite-plugin"
+  rm -f "$BUILDKITE_PLUGINS_PATH/monorepo-diff-buildkite-plugin"
+  rm -f "$BUILDKITE_PLUGINS_PATH/monorepo-diff-buildkite-plugin.version"
 
   # Stub curl to always fail on download
   stub curl \