host_rewrite causes canary deployment to fail

[concaf]

I have some test canary configuration like -

      apiVersion: ambassador/v1
      kind:  Mapping
      name:  qotm_mapping_1
      prefix: /qotm/
      service: qotm
      ---
      apiVersion: ambassador/v1
      kind:  Mapping
      name:  qotm_mapping_2
      prefix: /qotm/
      service: httpbin.org:80
      host_rewrite: httpbin.org
      weight: 50

One of the mappings is ignored completely and diag reports the error -

qotm.default.1: cannot accept new mapping qotm_mapping_2 with mismatched host_rewrite: httpbin.org != -unset-

As soon as I remove host_rewrite from the config, the canary starts working fine.

I can reproduce this every time right now, but I have a faint memory that this was intermittent while testing (might help while debugging)

[rbudiharso]

+1 on this, makes the canary not working

[kflynn]

So the fundamental issue here is that the host_rewrite element in the Envoy config is an attribute of a Route rather than of a Cluster. That means that we need to sort out how to get Envoy to split traffic across Routes, which we don't currently do.

The docs imply that this is doable, so there's a bit of a research project to sort out how to do it.

[kflynn]

(Estimating at 3 because I think it's relatively quick to find out whether the traffic-splitting thing is possible or not, but I'm less sure about exactly how much work lies beyond that.)

[rbudiharso]

I manage to solve this by specifying host_rewrite on both blocks and the canary starts to work.