[DPE-2345][DPE-2451] Add restore action

Extends #135 and
adds restore support.

This PR will override any conflicting index in case of restore. It also updates
list backups action to be shown in table format by default.

It adds 3x extra integration tests:
1) Snapshot / restore in the same cluster
2) Snapshot / remove / readd relation / restore
3) Snapshot / redeploy cluster / restore

actions.yaml

@@ -45,3 +45,21 @@ create-backup:
 
 list-backups:
   description: List available backup_ids in the S3 bucket and path provided by the S3 integrator charm.
+  params:
+    output:
+      type: string
+      default: "table"
+      description: |
+        Format which the data should be returned. Possible values: table, json.
+        The json format will bring more details, such as shard status, indices name, etc.
+
+restore:
+  description: Restore a database backup.
+    S3 credentials are retrieved from a relation with the S3 integrator charm.
+  params:
+    backup-id:
+      type: integer
+      description: |
+        A backup-id to identify the backup to restore. Format: <backup-id, int>
+  required:
+    - backup-id

lib/charms/opensearch/v0/helper_cluster.py

@@ -255,6 +255,24 @@ def shards(
         """Get all shards of all indexes in the cluster."""
         return opensearch.request("GET", "/_cat/shards", host=host, alt_hosts=alt_hosts)
 
+    @staticmethod
+    @retry(
+        stop=stop_after_attempt(3),
+        wait=wait_exponential(multiplier=1, min=2, max=10),
+        reraise=True,
+    )
+    def indices(
+        opensearch: OpenSearchDistribution,
+        host: Optional[str] = None,
+        alt_hosts: Optional[List[str]] = None,
+    ) -> List[Dict[str, str]]:
+        """Get all shards of all indexes in the cluster."""
+        idx = opensearch.request("GET", "/_cat/indices", host=host, alt_hosts=alt_hosts)
+        idx = {}
+        for index in opensearch.request("GET", "/_cat/indices", host=host, alt_hosts=alt_hosts):
+            idx[index["index"]] = {"health": index["health"], "status": index["status"]}
+        return idx
+
     @staticmethod
     def shards_by_state(
         opensearch: OpenSearchDistribution,