Elasticsearch: get current running snapshot operation - elasticsearch

Question

Assume, need to automate the snapshot restoring of 2 or more snapshots to elastic cluster.
It is necessary to detect, that snapshot operation is completed before next api call: _snaphot/<repository>/<snapshot>/_restore.
If I call while snapshot is restoring, cluster responses 503.
I tried to use thread pool api with running snapshot operation:
curl -XGET 'http://127.0.0.1:9200/_cat/thread_pool?h=snapshot.active
But, it returns 0 anyway.
What is proper way to do get info about current running restore operation?
UPDATE:
An example how have it managed to work with ansible:
- name: shell | restore latest snapshot
uri:
url: "http://127.0.0.1:9200/_snapshot/{{ es_snapshot_repository }}/snapshot_name/_restore"
method: "POST"
body: '{"index_settings":{"index.number_of_replicas": 0}}'
body_format: json
- name: shell | get state of active recovering operations | log indices
uri:
url: "http://127.0.0.1:9200/_recovery?active_only"
method: "GET"
register: response
until: "response.json == {}"
retries: 6
delay: 10

Answer 1

You can monitor status of indices being restored using Indices Recovery API.
The easiest way of doing this is looking at the stage property:
init: Recovery has not started
index: Reading index meta-data and copying bytes from source to destination
start: Starting the engine;
opening the index for use translog: Replaying transaction log
finalize: Cleanup done: Complete
done: Complete
Parameter active_only returns info about shards that are not in done state:
http://127.0.0.1:9200/_recovery?active_only