Identifier does not return on first successful match

According to linkerd docs: https://linkerd.io/config/1.0.0/linkerd/index.html#http-1-1-identifiers

If a list of identifiers is provided, each identifier is tried in turn until one successfully assigns a logical name to the request.

If I have a list of identifier as:

routers:
- protocol: http
  identifier:
    kind: io.l5d.header.token
    header: Custom-Header
  identifier:
    kind: io.l5d.path
    segments: 1
    consume: true

I would expect linkerd to return if the Custom-Header is included in the request and a match is made (not try path identifier). Currently I am seeing linkerd still try to route the service to the constructed path when the header is included.

$ http GET linkerd:4140/api/v1/hello Custom-Header:hello-world
HTTP/1.1 502 Bad Gateway
Content-Encoding: gzip
Content-Length: 106
Content-Type: text/plain
l5d-err: No+hosts+are+available+for+%2Fsvc%2Fapi%2C+Dtab.base%3D%5B%5D%2C+Dtab.local%3D%5B%5D.+Remote+Info%3A+Not+Available

No hosts are available for /svc/api, Dtab.base=[], Dtab.local=[]. Remote Info: Not Available

The service works correctly when I try to use the path identifier with and without the header.

If I reverse the order of the identifiers in the config I get a different error when using only path identifier with no Custom-Header:

Unknown Destination: Request("GET /hello-world/api/v1/hello", from /x.x.x.x:xxxx) / Custom-Header is absent.

Is this expected behavior?

[adleong]

Yes, that will use the header if it is present and fall back to the path otherwise.

[adleong]

You have the identifier property set twice in your linkerd config which will cause the first identifier to be overriden/replaced by the second one. Instead, you should provide a list of identifiers:

routers:
- protocol: http
  identifier:
  - kind: io.l5d.header.token
    header: Custom-Header
  - kind: io.l5d.path
    segments: 1
    consume: true

The difference is pretty subtle. I’ve filed https://github.com/linkerd/linkerd/issues/1262 to make it so that duplicate properties will raise an error.