Update API: Setting ctx.op to random string results in noop

[spinscale]

Elasticsearch version (bin/elasticsearch --version): 7.1.1

Description of the problem including expected versus actual behavior:

When using a script in the Update API, setting ctx.op to any string will result in a noop. IMO this should throw an exception, if it's anything else than the suggested ones.

This leniency is actually documented with a TODO, but I do not know the history behind that (that todo is from early 2017). Also a warn message is logged.

Steps to reproduce:

DELETE test

PUT test/_doc/1
{
  "key" : "value"
}

POST test/_update/1
{
  "script": {
    "source": "ctx._source.foo = 'bar'; ctx.op ='anything'",
    "lang": "painless"
  }
}

# document unchanged
GET test/_doc/1

[elasticmachine]

Pinging @elastic/es-distributed

[panwarab]

can I take this up? @spinscale @dnhatn

[dnhatn]

@abhiroj Yes

[panwarab]

cool! how should I get started to reproduce it @dnhatn can you point me to the Class

[henningandersen]

@abhiroj I think resolving this takes following steps:

1.reproduce it using the example above against an elasticsearch node.
2. write a test that provokes the same, either as an ESIntegTestCase that does such an update against a test node and/or a ESTestCase that runs against UpdateHelper more directly.
3. remove the leniency and figuring out what kind of error reporting to do.
4. run the full suite of tests
5. repeat step 1 and check that things look good when running against a real node too.
6. open a PR with your changes.

[zacharymorn]

It’s still present in the latest code base

# Request 
 curl -XPOST  'http://localhost:9200/test/_update/1' -H 'Content-Type: application/json' -u elastic-admin:elastic-password -d '
{
  "script": {
    "source": "ctx._source.foo = '\''bar'\''; ctx.op = '\''anything'\''",
    "lang": "painless"
  }
}'

# Response (“noop” for the result field)
{"_index":"test","_id":"1","_version":1,"result":"noop","_shards":{"total":0,"successful":0,"failed":0},"_seq_no":0,"_primary_term":1}

@abhiroj , are you currently working on this? If not I can take this up.

[zacharymorn]

@spinscale I've create a WIP PR for this, please let me know if this aligns with what you are considering.

[zacharymorn]

@spinscale Any update on this?