Kill dockerd immediately on container exit

When dockerd is running inside the container, skip exec so the
entrypoint shell stays alive to run an EXIT trap that SIGKILL's
dockerd. This avoids a ~60s wait for dockerd's graceful shutdown
when the agent process exits.

Author: heapoutofspace

assets/entrypoint.sh

@@ -10,6 +10,7 @@ if [ "${ASYLUM_DOCKER:-}" = "1" ]; then
     elif command -v dockerd >/dev/null 2>&1; then
         echo "Starting Docker daemon..."
         sudo dockerd --storage-driver=vfs --log-level=warn >/tmp/dockerd.log 2>&1 &
+        DOCKERD_PID=$!
         for i in $(seq 1 30); do
             if docker info >/dev/null 2>&1; then
                 echo "Docker daemon ready"
@@ -140,4 +141,11 @@ if [ -t 0 ] && [ -t 1 ]; then
     echo ""
 fi
 
-exec "$@"
+# If dockerd is running, skip exec so the trap can kill it on exit.
+# Otherwise, exec replaces this shell (saves a process).
+if [ -n "${DOCKERD_PID:-}" ]; then
+    trap 'sudo kill -9 $DOCKERD_PID 2>/dev/null' EXIT
+    "$@"
+else
+    exec "$@"
+fi