[FORBIDDEN/12/index read-only / allow delete (api)] - read only elasticsearch indices

If your elasticsearch is responding with 403 and this message:

  "type": "cluster_block_exception",
  "reason": "blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"

Then you probably recovered from a full hard drive. The thing is, elasticsearch is switching to read-only if it cannot index more documents because your hard drive is full. With this it ensures availability for read-only queries. Elasticsearch will not switch back automatically but you can disable it by sending

curl -XPUT -H "Content-Type: application/json" http://localhost:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'

Happy indexing!