rollover `max_docs` uses doc count from both primary and replica/s

[jpcarey]

Elasticsearch version: 5.3.0

The rollover max_docs value uses the doc count from both primary and replica/s. It should be based upon the primary only, since the replica count can be changed.

(start two nodes, to allow the default 1 replica to allocate)

PUT /logs-000001 
{
  "aliases": {
    "logs_write": {}
  }
}
PUT logs_write/test/1
{
  "blah": "foo"
}
POST /logs_write/_rollover?dry_run
{
  "conditions": {
    "max_docs":  2
  }
}
# response
{
  "old_index": "logs-000001",
  "new_index": "logs-000002",
  "rolled_over": false,
  "dry_run": true,
  "acknowledged": false,
  "shards_acknowledged": false,
  "conditions": {
    "[max_docs: 2]": true
  }
}

change the replica count to 0:

PUT /logs-000001/_settings
{
  "index": {
    "number_of_replicas": 0
  }
}
# response
{
  "old_index": "logs-000001",
  "new_index": "logs-000002",
  "rolled_over": false,
  "dry_run": true,
  "acknowledged": false,
  "shards_acknowledged": false,
  "conditions": {
    "[max_docs: 2]": false
  }
}

[eticzon]

Hi @jpcarey, @clintongormley! I'd like to adopt this issue, if that's OK. It's my first time contributing to the project so if you guys are OK with me picking this up, I'll sign the CLA. Thanks!

[clintongormley]

@eticzon great

Thanks for showing interest in contributing to Elasticsearch.

Here's a guide to how to go about it: https://github.com/elastic/elasticsearch/blob/master/CONTRIBUTING.md

[julemik]

Appreciate it Eticzon. I too am experiencing the issue. Doubled my max_docs for temporary solution.

[fred84]

@eticzon would you mind if I will handle this issue?

@jpcarey @clintongormley I fixed rollover condition (fred84@0dc2ec3) with integration test successfully passing, but I'm currently struggling with passing full "gradle check"