The root reason of flakes, was that server was considered as ready to
early.
In particular:
```
../../bin/etcd-2456648: {"level":"info","ts":"2021-01-11T09:56:44.474+0100","caller":"rafthttp/stream.go:274","msg":"established TCP streaming connection with remote peer","stream-writer-type":"stream Message","local-member-id":"ed5f620d34a8e61b","remote-peer-id":"ca50e9357181d758"}
../../bin/etcd-2456648: {"level":"warn","ts":"2021-01-11T09:56:49.040+0100","caller":"etcdserver/server.go:1942","msg":"failed to publish local member to cluster through raft","local-member-id":"ed5f620d34a8e61b","local-member-attributes":"{Name:infra2 ClientURLs:[http://localhost:20030]}","request-path":"/0/members/ed5f620d34a8e61b/attributes","publish-timeout":"7s","error":"etcdserver: request timed out, possibly due to connection lost"}
../../bin/etcd-2456648: {"level":"info","ts":"2021-01-11T09:56:49.049+0100","caller":"etcdserver/server.go:1921","msg":"published local member to cluster through raft","local-member-id":"ed5f620d34a8e61b","local-member-attributes":"{Name:infra2 ClientURLs:[http://localhost:20030]}","request-path":"/0/members/ed5f620d34a8e61b/attributes","cluster-id":"34f27e83b3bc2ff","publish-timeout":"7s"}
```
was taking 5s. If this was happening concurrently with etcdctl, the
etcdctl could timeout.
The fix, requires servers to report 'ready to serve client requests' to consider them up.
Fixed also some whitelisted 'goroutines'.
This CL fixes:
COVERDIR=./coverage PASSES="build_cov" && go test --tags cov -v ./tests/e2e
and is part of the effort to make:
COVERDIR=coverage PASSES="build_cov cov" ./test
fully pass.
The args passed to ./bin/etcd_test and ./bin/etcdctl_test binaries were
mismatched. The protocol of passing the arguments using
environment variables has been replaces with proper passing of flags.
How the measurement of coverage by e2e tests works:
1. COVERDIR=./coverage PASSES="build_cov" are generating
./bin/etcd_test and ./bin/etcdctl_test binaries.
2. These binaries are tests (as coverage can be computed only for
tests) [see ./main_test.go ./etcdctl/main_test.go], but this tests are
running the main logic of the server and uppon termination (or SIGTERM
signal) are writting proper .coverprofile files in the $COVERDIR folder.
The binaries used to take arguments using env variables, but its not
needed any longer. The binaries can consume any command line arguments
that either test (so --test.fooo) or the original binary can consume.
3. The tests/e2e (when compiled with the --tags cov) are starting the
_test binaries instead of the original binaries, such that the coverage
is being collected.
This change makes the etcd package compatible with the existing Go
ecosystem for module versioning.
Used this tool to update package imports:
https://github.com/KSubedi/gomove
