failed to retrieve password hash for reserved user [elastic] org.elasticsearch.action.UnavailableShardsException: at least one primary shard for the index [.security-7] is unavailable
You'll get this issue when in your cluster, the nodes are unable to contain the system index ( like ".index, .security, .kibana etc." ) for resolving this issue-
Add the node role as "data_content"
the YML setting will be- node roles: [data_content, other node roles whichever you want separated by comma]
For Dedicated Master Node setting will be: node roles: [data_content, master]
Incase you want to refer the the elastic doc- Node | Elasticsearch Guide [8.11] | Elastic
Hope this will resolve the issue.