e2e tests README (#331)

test/e2e/README.md

@@ -0,0 +1,56 @@
+# YTsaurus operator e2e test
+
+## General
+Source of truth of configuration and commands to run e2e tests is in the [e2e Github action](https://github.com/ytsaurus/ytsaurus-k8s-operator/blob/main/.github/workflows/subflow_run_e2e_tests.yaml#L34-L49).
+The flow:
+1) create k8s ([Kind](https://kind.sigs.k8s.io/)) cluster
+2) build the YTsaurus operator helm chart
+3) install helm chart in the Kind cluster
+4) preload test YTsaurus images in kind so pods wouldn't have to download them in tests every time
+5) run e2e tests with `make test-e2e`
+
+## Development
+In the development, kind cluster (with preloaded images) can be created once and reused between e2e runs. To achieve that just use `make install` to install CRD's instead of `make helm-kind-install`.
+
+Also, it is possible to run the YTsaurus operator main process outside of k8s cluster, for example, to be able to use a debugger. To have such a configuration, a developer should set `E2E_HTTP_PROXY_INTERNAL_PORT` env variable (for example `E2E_HTTP_PROXY_INTERNAL_PORT=9000`) 
+and `YTOP_PROXY` env variable with matching port (for example `YTOP_PROXY=127.0.0.1:9000`) before running the e2e tests.   
+This way HTTP proxies of YTsaurus clusters will listen the specified port, and the YTsaurus operator code launched outside of the k8s cluster will use this port to connect to the proxy.
+
+### Note for the MacOS users
+One needs to publish ports in Kind's docker container to make the specified port available outside of Kind on MacOS.
+To achieve that, the next approach can be used:
+1. create Kind cluster with some ports forwarded, for example
+```
+# kind-config.yaml
+
+apiVersion: kind.x-k8s.io/v1alpha4
+kind: Cluster
+nodes:
+  - role: control-plane
+    extraPortMappings:
+      - containerPort: 30000
+        hostPort: 9000
+      - containerPort: 30001
+        hostPort: 9001
+      - containerPort: 30010
+        hostPort: 9010
+      - containerPort: 30011
+        hostPort: 9011
+      - containerPort: 30020
+        hostPort: 9020
+      - containerPort: 30021
+        hostPort: 9021
+```
+```
+# create_kind.sh
+kind create cluster --config=kind-config.yaml
+# also cert manager required for operator to work
+kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.11.0/cert-manager.yaml
+```
+2. Configure env variables
+```
+YTOP_PROXY=127.0.0.1:9000
+E2E_HTTP_PROXY_INTERNAL_PORT=30000
+```
+
+RPC proxy can be configured in a similar way, if needed `E2E_YT_RPC_PROXY=127.0.0.1:9001; E2E_RPC_PROXY_INTERNAL_PORT=30001`.