[BUG] Bulk API ignores the specified ingest pipeline in the bulk item

[gaobinlong]

Describe the bug

When diving deep on this issue, I found a new issue in bulk API, when there's a specified ingest pipeline in the update action with upsert, the pipeline will not be executed, which should be a bug.

Related component

Indexing

To Reproduce

1. Create an ingest pipeline

PUT _ingest/pipeline/test_pipeline
{
  "processors": [
    {
      "set": {
        "field": "z",
        "value": 100
      }
    }]
}

2. Bulk update with upsert, the document with ID 1 doesn't exist

POST /_bulk
{"update":{"_index":"test1","_id":"1", "pipeline":"test_pipeline"}}
{"upsert":{"x":3,"y":5},"script":{"source":"ctx._source.x += 1"}}

3. Get the document :
   Get test1/_doc/1
   the result is:

{
  "_index": "test1",
  "_id": "1",
  "_version": 1,
  "_seq_no": 0,
  "_primary_term": 1,
  "found": true,
  "_source": {
    "x": 3,
    "y": 5
  }
}

, we can see that the document doesn't contain the field z which is set by the ingest pipeline. But if we set the ingest pipeline in the create action, it works well:

POST /_bulk
{"create":{"_index":"test1","_id":"1", "pipeline":"test_pipeline"}}
{"x":3,"y":5}

, the result is:

{
  "_index": "test1",
  "_id": "1",
  "_version": 1,
  "_seq_no": 0,
  "_primary_term": 1,
  "found": true,
  "_source": {
    "x": 3,
    "y": 5,
    "z": 100
  }
}

Expected behavior

Bulk API should resolve the ingest pipeline specified in the update action with upsert.

Additional Details

Host/Environment (please complete the following information):

• OS: [MacOS]
• Version [3.0.0]

[gaobinlong]

Closed by #12883.