[BUG] Compressed bulk index request failures

[thomas-long-f3]

Describe the bug

When upgrading from 2.16.0 > 2.17.0, all compressed bulk index requests fail.

Related component

Indexing

To Reproduce

Testing using the OpenSearch docker images. Single node mode, with security disabled.

1. Generate a simple request:

echo '{ "index": { "_index": "test" } }
{ "hello": "world" }
' > bulk.json

2. Perform a bulk request uncompressed:

curl http://localhost:9200/_bulk -H 'Content-Type: application/json' --data-binary @bulk.json

Successful response:

{"took":7,"errors":false,"items":[{"index":{"_index":"test","_id":"4pV3D5IBj6h56HIDqJfa","_version":1,"result":"created","_shards":{"total":2,"successful":1,"failed":0},"_seq_no":1,"_primary_term":1,"status":201}}]}

3. Now compress the same file:

gzip bulk.json

4. Send a compressed request:

curl http://localhost:9200/_bulk -H 'Content-Type: application/json' -H 'Content-Encoding: gzip' --data-binary @bulk.json.gz

Request fails:

{"error":{"root_cause":[{"type":"illegal_argument_exception","reason":"The bulk request must be terminated by a newline [\\n]"}],"type":"illegal_argument_exception","reason":"The bulk request must be terminated by a newline [\\n]"},"status":400}

Note the file does contain a newline at the end, and works as expected on previous OS versions.

Expected behavior

A compressed request would be successful, like the uncompressed request.

Additional Details

Plugins
Please list all plugins currently enabled.

Screenshots
If applicable, add screenshots to help explain your problem.

Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.