mirror mount-buildkite-agent implementation from docker-buildkite-plugin

README.md

@@ -359,6 +359,12 @@ Whether to match the user ID and group ID for the container user to the user ID
 
 Using this option ensures that any files created on shared mounts from within the container will be accessible to the host user. It is otherwise common to accidentally create root-owned files that Buildkite will be unable to remove, since containers by default run as the root user.
 
+### `mount-buildkite-agent` (optional, run-only, boolean)
+
+Whether to automatically mount the `buildkite-agent` binary and associated environment variables from the host agent machine into the container.
+
+Default: `false`
+
 ### `pull-retries` (optional)
 
 A number of times to retry failed docker pull. Defaults to 0.

commands/run.sh

@@ -155,6 +155,28 @@ if [[ -n "$(plugin_read_config ENTRYPOINT)" ]] ; then
   run_params+=("--entrypoint \"$(plugin_read_config ENTRYPOINT)\"")
 fi
 
+# Optionally handle the mount-buildkite-agent option
+if [[ "$(plugin_read_config MOUNT_BUILDKITE_AGENT "false")" == "true" ]]; then
+  if [[ -z "${BUILDKITE_AGENT_BINARY_PATH:-}" ]] ; then
+    if ! command -v buildkite-agent >/dev/null 2>&1 ; then
+      echo -n "+++ 🚨 Failed to find buildkite-agent in PATH to mount into container, "
+      echo "you can disable this behaviour with 'mount-buildkite-agent:false'"
+    else
+      BUILDKITE_AGENT_BINARY_PATH=$(command -v buildkite-agent)
+    fi
+  fi
+fi
+
+# Mount buildkite-agent if we have a path for it
+if [[ -n "${BUILDKITE_AGENT_BINARY_PATH:-}" ]] ; then
+  run_params+=(
+    "-e" "BUILDKITE_JOB_ID"
+    "-e" "BUILDKITE_BUILD_ID"
+    "-e" "BUILDKITE_AGENT_ACCESS_TOKEN"
+    "-v" "$BUILDKITE_AGENT_BINARY_PATH:/usr/bin/buildkite-agent"
+  )
+fi
+
 run_params+=("$run_service")
 
 build_params=(--pull)
@@ -298,7 +320,8 @@ set -e
 
 if [[ $exitcode -ne 0 ]] ; then
   echo "^^^ +++"
-  echo "+++ :warning: Failed to run command, exited with $exitcode"
+  echo "+++ :warning: Failed to run command, exited with $exitcode, run params:"
+  echo "${run_params[@]}"
 fi
 
 if [[ -n "${BUILDKITE_AGENT_ACCESS_TOKEN:-}" ]] ; then

plugin.yml

@@ -72,6 +72,8 @@ configuration:
       type: string
     propagate-uid-gid:
       type: boolean
+    mount-buildkite-agent:
+      type: boolean
   oneOf:
     - required:
       - run
@@ -97,3 +99,4 @@ configuration:
     workdir: [ run ]
     user: [ run ]
     propagate-uid-gid: [ run ]
+    mount-buildkite-agent: [ run ]