api: fix TLS when redirecting the request

[rleungx]

What problem does this PR solve?

Start 2 PD:
pd1: client-urls: 127.0.0.1:2379, peer-urls: 127.0.0.1:2380
pd2: client-urls: 127.0.0.1:2479, peer-urls: 127.0.0.1:2480

From PD log:
Before:
pd1:

[2019/09/09 13:54:31.332 +08:00] [ERROR] [redirector.go:97] ["request failed"] [error="Get https://127.0.0.1:2379/pd/ping: x509: certificate signed by unknown authority"]
[2019/09/09 13:55:31.332 +08:00] [ERROR] [redirector.go:97] ["request failed"] [error="Get https://127.0.0.1:2379/pd/ping: x509: certificate signed by unknown authority"]

pd2:

[2019/09/09 14:30:00.098 +08:00] [WARN] [config_logging.go:258] ["rejected connection"] [remote-addr=127.0.0.1:53098] [server-name=] [error="remote error: tls: bad certificate"]
[2019/09/09 14:30:01.366 +08:00] [WARN] [config_logging.go:258] ["rejected connection"] [remote-addr=127.0.0.1:53106] [server-name=] [error="remote error: tls: bad certificate"]

After: no such error

From curl:
Before:

curl --cacert /path/to/ca.pem --cert /path/to/pd-server.pem --key /path/to/pd-server-key.pem https://127.0.0.1:2479/pd/ping
redirect failed

After: no such error

What is changed and how it works?

This PR fixes the TLS problem when redirecting the request.

Check List

Tests

• Manual test

Related changes

• Need to cherry-pick to the release branch
• Need to be included in the release notes

[codecov-io]

Codecov Report

Merging #1740 into master will decrease coverage by 0.05%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master    #1740      +/-   ##
==========================================
- Coverage   76.83%   76.77%   -0.06%     
==========================================
  Files         162      162              
  Lines       15832    15844      +12     
==========================================
  Hits        12165    12165              
- Misses       2650     2654       +4     
- Partials     1017     1025       +8

Impacted Files	Coverage Δ
server/api/redirector.go	76.81% <75%> (-0.39%)	⬇️
pkg/etcdutil/etcdutil.go	76.81% <0%> (-11.6%)	⬇️
server/tso/tso.go	78.89% <0%> (-4.59%)	⬇️
server/server.go	81.83% <0%> (-1.92%)	⬇️
server/core/storage.go	76.08% <0%> (-1.45%)	⬇️
server/member/leader.go	74.48% <0%> (-1.03%)	⬇️
server/config/option.go	91.85% <0%> (-0.75%)	⬇️
server/grpc_service.go	57.91% <0%> (+0.43%)	⬆️
server/handler.go	50.13% <0%> (+0.52%)	⬆️
client/client.go	69.89% <0%> (+1.29%)	⬆️
... and 2 more

---

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[Connor1996]

LGTM

[shafreeck]

LGTM

[sre-bot]

/run-all-tests

[sre-bot]

cherry pick to release-3.0 failed

[sre-bot]

cherry pick to release-2.1 failed

[sre-bot]

cherry pick to release-3.1 failed

[onitake]

When will this land in a PD release?
I discovered that version 3.0.4 is not usable for me because I'm running into the certificate validation issue. Will there be a 3.1 or 4.0 soon?

[rleungx]

@onitake This fix will land in 3.0.5 soon.

[onitake]

@rleungx Thanks!