mirror of https://github.com/linkerd/linkerd2.git
06ef634a9b
Closes #6253 ### What --- When we send a profile request with a pod IP, we get back an endpoint as part of the response. This has two advantages: we avoid building a load balancer and we can treat endpoint failure differently (with more of a fail fast approach). At the moment, when we use a pod DNS as the target of the profile lookup, we don't have an endpoint returned in the response. Through this change, the behaviour will be consistent. Whenever we look up a pod (either through IP or DNS name) we will get an endpoint back. The change also attempts to simplify some of the logic in GetProfile. ### How --- We already have a way to build an endpoint and return it back to the client; I sought to re-use most of the code in an effort to also simplify `GetProfile()`. I extracted most of the code that would have been duplicated into a separate method that is responsible for building the address, looking at annotations for opaque ports and for sending the response back. In addition, to support a pod DNS fqn I've expanded on the `else` branch of the topmost if statement -- if our host is not an IP, we parse the host to get the k8s fqn. If the parsing function returns an instance ID along with the ServiceID, then we know we are dealing directly with a pod -- if we do, we fetch the pod using the core informer and then return an endpoint for it. ### Tests --- I've tested this mostly with the destination client script. For the tests, I used the following pods: ``` ❯ kgp -n emojivoto -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES voting-ff4c54b8d-zbqc4 2/2 Running 0 3m58s 10.42.0.53 k3d-west-server-0 <none> <none> web-0 2/2 Running 0 3m58s 10.42.0.55 k3d-west-server-0 <none> <none> vote-bot-7d89964475-tfq7j 2/2 Running 0 3m58s 10.42.0.54 k3d-west-server-0 <none> <none> emoji-79cc56f589-57tsh 2/2 Running 0 3m58s 10.42.0.52 k3d-west-server-0 <none> <none> # emoji pod has an opaque port set to 8080. # web-svc is a headless service and it backs a statefulset (which is why we have web-0). # without a headless service we can't lookup based on pod DNS. ``` **`Responses before the change`**: ``` # request on IP, this is how things work at the moment. I included this because there shouldn't be # any diff between the response given here and the response we get with the change. # note: this corresponds to the emoji pod which has opaque ports set to 8080. ❯ go run controller/script/destination-client/main.go -method getProfile -path 10.42.0.52:8080 INFO[0000] opaque_protocol:true retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} endpoint:{addr:{ip:{ipv4:170524724} port:8080} weight:10000 metric_labels:{key:"control_plane_ns" value:"linkerd"} metric_labels:{key:"deployment" value:"emoji"} metric_labels:{key:"namespace" value:"emojivoto"} metric_labels:{key:"pod" value:"emoji-79cc56f589-57tsh"} metric_labels:{key:"pod_template_hash" value:"79cc56f589"} metric_labels:{key:"serviceaccount" value:"emoji"} tls_identity:{dns_like_identity:{name:"emoji.emojivoto.serviceaccount.identity.linkerd.cluster.local"}} protocol_hint:{h2:{} opaque_transport:{inbound_port:4143}}} INFO[0000] # request web-0 by IP # there shouldn't be any diff with the response we get after the change ❯ go run controller/script/destination-client/main.go -method getProfile -path 10.42.0.55:8080 INFO[0000] retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} endpoint:{addr:{ip:{ipv4:170524727} port:8080} weight:10000 metric_labels:{key:"control_plane_ns" value:"linkerd"} metric_labels:{key:"namespace" value:"emojivoto"} metric_labels:{key:"pod" value:"web-0"} metric_labels:{key:"serviceaccount" value:"web"} metric_labels:{key:"statefulset" value:"web"} tls_identity:{dns_like_identity:{name:"web.emojivoto.serviceaccount.identity.linkerd.cluster.local"}} protocol_hint:{h2:{}}} INFO[0000] # request web-0 by DNS name -- will not work. ❯ go run controller/script/destination-client/main.go -method getProfile -path web-0.web-svc.emojivoto.svc.cluster.loc al:8080 INFO[0000] fully_qualified_name:"web-0.web-svc.emojivoto.svc.cluster.local" retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} dst_overrides:{authority:"web-svc.emojivoto.svc.cluster.local.:8080" weight:10000} INFO[0000] INFO[0000] fully_qualified_name:"web-0.web-svc.emojivoto.svc.cluster.local" retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} dst_overrides:{authority:"web-svc.emojivoto.svc.cluster.local.:8080" weight:10000} INFO[0000] # ^ # | # --> no endpoint in the response ``` **`Responses after the change`**: ``` # request profile for emoji, we see opaque transport being set on the endpoint. ❯ go run controller/script/destination-client/main.go -method getProfile -path 10.42.0.52:8080 INFO[0000] opaque_protocol:true retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} endpoint:{addr:{ip:{ipv4:170524724} port:8080} weight:10000 metric_labels:{key:"control_plane_ns" value:"linkerd"} metric_labels:{key:"deployment" value:"emoji"} metric_labels:{key:"namespace" value:"emojivoto"} metric_labels:{key:"pod" value:"emoji-79cc56f589-57tsh"} metric_labels:{key:"pod_template_hash" value:"79cc56f589"} metric_labels:{key:"serviceaccount" value:"emoji"} tls_identity:{dns_like_identity:{name:"emoji.emojivoto.serviceaccount.identity.linkerd.cluster.local"}} protocol_hint:{h2:{} opaque_transport:{inbound_port:4143}}} INFO[0000] # request profile for web-0 with IP. ❯ go run controller/script/destination-client/main.go -method getProfile -path 10.42.0.55:8080 INFO[0000] retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} endpoint:{addr:{ip:{ipv4:170524727} port:8080} weight:10000 metric_labels:{key:"control_plane_ns" value:"linkerd"} metric_labels:{key:"namespace" value:"emojivoto"} metric_labels:{key:"pod" value:"web-0"} metric_labels:{key:"serviceaccount" value:"web"} metric_labels:{key:"statefulset" value:"web"} tls_identity:{dns_like_identity:{name:"web.emojivoto.serviceaccount.identity.linkerd.cluster.local"}} protocol_hint:{h2:{}}} INFO[0000] # request profile for web-0 with pod DNS, resp contains endpoint. ❯ go run controller/script/destination-client/main.go -method getProfile -path web-0.web-svc.emojivoto.svc.cluster.local:8080 INFO[0000] retry_budget:{retry_ratio:0.2 min_retries_per_second:10 ttl:{seconds:10}} endpoint:{addr:{ip:{ipv4:170524727} port:8080} weight:10000 metric_labels:{key:"control_plane_ns" value:"linkerd"} metric_labels:{key:"namespace" value:"emojivoto"} metric_labels:{key:"pod" value:"web-0"} metric_labels:{key:"serviceaccount" value:"web"} metric_labels:{key:"statefulset" value:"web"} tls_identity:{dns_like_identity:{name:"web.emojivoto.serviceaccount.identity.linkerd.cluster.local"}} protocol_hint:{h2:{}}} INFO[0000] ``` Signed-off-by: Matei David <matei@buoyant.io> |
||
|---|---|---|
| .. | ||
| destination | ||
| util | ||