add SIGKILL note, add lock filename to log (#2447)

Author: gazarenkov

docker/install-dynamic-plugins.py

@@ -219,7 +219,7 @@ def remove_lock(lock_file_path):
 
 # Wait for the lock file to be released
 def wait_for_lock_release(lock_file_path):
-   print("======= Waiting for lock release...", flush=True)
+   print(f"======= Waiting for lock release (file: {lock_file_path})...", flush=True)
    while True:
      if not os.path.exists(lock_file_path):
        break

docs/dynamic-plugins/installing-plugins.md

@@ -124,11 +124,18 @@ When using the Operator ....
 
 The directory where dynamic plugins are located is mounted as a volume to the _install-dynamic-plugins_ init container and the _backstage-backend_ container. The _install-dynamic-plugins_ init container is responsible for downloading and extracting the plugins into this directory. Depending on the deployment method, the directory is mounted as an ephemeral or persistent volume. In the latter case, the volume can be shared between several Pods, and the plugins installation script is also responsible for downloading and extracting the plugins only once, avoiding conflicts.
 
-**Important Note:** If _install-dynamic-plugins_ init container was killed with SIGKILL signal (for example in a case of OOM) the script is not able to remove the lock file and the next time the Pod starts, it will be waiting for the lock release. You can see the following message in the logs for all the Pods:
+**Important Note:** If _install-dynamic-plugins_ init container was killed with SIGKILL signal, which may happen due to the following reasons:
+* pod eviction (to free up node resources),
+* pod deletion (if not terminated with SIGTERM within graceful period),
+* node shutdown,
+* container runtime issues,
+* exceeding resource limits (OOM for example)
+
+the script is not able to remove the lock file and the next time the Pod starts, it will be waiting for the lock release. You can see the following message in the logs for all the Pods:
 
 ```console
 oc logs -n <namespace-name> -f backstage-<backstage-name>-<pod-suffix> -c install-dynamic-plugins
-======= Waiting for lock release...
+======= Waiting for lock release (file: /dynamic-plugins-root/install-dynamic-plugins.lock)...
 ```
 In such a case, you can delete the lock file manually from any of the Pods: