#### etcd-test-proxy

Proxy layer that simulates various network conditions.

Test locally

```bash
$ ./build
$ ./bin/etcd

$ make build-etcd-test-proxy -f ./hack/scripts-dev/Makefile

$ ./bin/etcd-test-proxy --help
$ ./bin/etcd-test-proxy --from localhost:23790 --to localhost:2379 --http-port 2378 --verbose

$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:2379 put foo bar
$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:23790 put foo bar
```

Proxy overhead per request is under 500μs

```bash
$ go build -v -o ./bin/benchmark ./tools/benchmark

$ ./bin/benchmark \
  --endpoints localhost:2379 \
  --conns 5 \
  --clients 15 \
  put \
  --key-size 48 \
  --val-size 50000 \
  --total 10000

<<COMMENT
Summary:
  Total:	8.4611 secs.
  Slowest:	0.1324 secs.
  Fastest:	0.0011 secs.
  Average:	0.0121 secs.
  Stddev:	0.0125 secs.
  Requests/sec:	1181.8758

Response time histogram:
  0.0011 [1]	|
  0.0142 [7899]	|∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
  0.0273 [1339]	|∎∎∎∎∎∎
  0.0405 [543]	|∎∎
  0.0536 [67]	|
  0.0667 [49]	|
  0.0798 [9]	|
  0.0930 [15]	|
  0.1061 [42]	|
  0.1192 [21]	|
  0.1324 [15]	|

Latency distribution:
  10% in 0.0049 secs.
  25% in 0.0064 secs.
  50% in 0.0085 secs.
  75% in 0.0126 secs.
  90% in 0.0243 secs.
  95% in 0.0307 secs.
  99% in 0.0686 secs.
  99.9% in 0.1294 secs.
COMMENT

$ ./bin/benchmark \
  --endpoints localhost:23790 \
  --conns 5 \
  --clients 15 \
  put \
  --key-size 48 \
  --val-size 50000 \
  --total 10000

<<COMMENT
Summary:
  Total:	9.1128 secs.
  Slowest:	0.1363 secs.
  Fastest:	0.0015 secs.
  Average:	0.0131 secs.
  Stddev:	0.0113 secs.
  Requests/sec:	1097.3613

Response time histogram:
  0.0015 [1]	|
  0.0150 [7407]	|∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
  0.0285 [2017]	|∎∎∎∎∎∎∎∎∎∎
  0.0419 [440]	|∎∎
  0.0554 [30]	|
  0.0689 [13]	|
  0.0824 [12]	|
  0.0959 [48]	|
  0.1093 [2]	|
  0.1228 [16]	|
  0.1363 [14]	|

Latency distribution:
  10% in 0.0054 secs.
  25% in 0.0071 secs.
  50% in 0.0100 secs.
  75% in 0.0153 secs.
  90% in 0.0241 secs.
  95% in 0.0297 secs.
  99% in 0.0584 secs.
  99.9% in 0.1312 secs.
COMMENT
```

Delay client transmit

```bash
$ curl -L http://localhost:2378/delay-tx -X PUT \
  -d "latency=5s&random-variable=100ms"
# added send latency 5s±100ms (current latency 4.92143955s)

$ curl -L http://localhost:2378/delay-tx
# current send latency 4.92143955s

$ ETCDCTL_API=3 ./bin/etcdctl \
  --endpoints localhost:23790 \
  --command-timeout=3s \
  put foo bar
# Error: context deadline exceeded

$ curl -L http://localhost:2378/delay-tx -X DELETE
# removed latency 4.92143955s

$ curl -L http://localhost:2378/delay-tx
# current send latency 0s

$ ETCDCTL_API=3 ./bin/etcdctl \
  --endpoints localhost:23790 \
  --command-timeout=3s \
  put foo bar
# OK
```

Pause client transmit

```bash
$ curl -L http://localhost:2378/pause-tx -X PUT
# paused forwarding [tcp://localhost:23790 -> tcp://localhost:2379]

$ ETCDCTL_API=3 ./bin/etcdctl \
  --endpoints localhost:23790 \
  put foo bar
# Error: context deadline exceeded

$ curl -L http://localhost:2378/pause-tx -X DELETE
# unpaused forwarding [tcp://localhost:23790 -> tcp://localhost:2379]
```

Drop client packets

```bash
$ curl -L http://localhost:2378/blackhole-tx -X PUT
# blackholed; dropping packets [tcp://localhost:23790 -> tcp://localhost:2379]

$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:23790 put foo bar
# Error: context deadline exceeded

$ curl -L http://localhost:2378/blackhole-tx -X DELETE
# unblackholed; restart forwarding [tcp://localhost:23790 -> tcp://localhost:2379]
```

Trigger leader election

```bash
$ ./build
$ make build-etcd-test-proxy -f ./hack/scripts-dev/Makefile

$ rm -rf /tmp/etcd-test-proxy-data.s*
$ goreman -f ./tools/etcd-test-proxy/Procfile start

$ ETCDCTL_API=3 ./bin/etcdctl \
  --endpoints localhost:13790,localhost:23790,localhost:33790 \
  member list

# isolate s1 when s1 is the current leader
$ curl -L http://localhost:1381/blackhole-tx -X PUT
$ curl -L http://localhost:1381/blackhole-rx -X PUT
# s1 becomes follower after election timeout
```