open-consul/agent/rpcclient
R.B. Boyer 642b75b60b
health: ensure /v1/health/service/:service endpoint returns the most recent results when a filter is used with streaming (#12640)
The primary bug here is in the streaming subsystem that makes the overall v1/health/service/:service request behave incorrectly when servicing a blocking request with a filter provided.

There is a secondary non-streaming bug being fixed here that is much less obvious related to when to update the `reply` variable in a `blockingQuery` evaluation. It is unlikely that it is triggerable in practical environments and I could not actually get the bug to manifest, but I fixed it anyway while investigating the original issue.

Simple reproduction (streaming):

1. Register a service with a tag.

        curl -sL --request PUT 'http://localhost:8500/v1/agent/service/register' \
            --header 'Content-Type: application/json' \
            --data-raw '{ "ID": "ID1", "Name": "test", "Tags":[ "a" ], "EnableTagOverride": true }'

2. Do an initial filter query that matches on the tag.

        curl -sLi --get 'http://localhost:8500/v1/health/service/test' --data-urlencode 'filter=a in Service.Tags'

3. Note you get one result. Use the `X-Consul-Index` header to establish
   a blocking query in another terminal, this should not return yet.

        curl -sLi --get 'http://localhost:8500/v1/health/service/test?index=$INDEX' --data-urlencode 'filter=a in Service.Tags'

4. Re-register that service with a different tag.

        curl -sL --request PUT 'http://localhost:8500/v1/agent/service/register' \
            --header 'Content-Type: application/json' \
            --data-raw '{ "ID": "ID1", "Name": "test", "Tags":[ "b" ], "EnableTagOverride": true }'

5. Your blocking query from (3) should return with a header
   `X-Consul-Query-Backend: streaming` and empty results if it works
   correctly `[]`.

Attempts to reproduce with non-streaming failed (where you add `&near=_agent` to the read queries and ensure `X-Consul-Query-Backend: blocking-query` shows up in the results).
2022-04-27 10:39:45 -05:00
..
health health: ensure /v1/health/service/:service endpoint returns the most recent results when a filter is used with streaming (#12640) 2022-04-27 10:39:45 -05:00