rest error simulator

Simulates errors on REST API (data plane)
Available Simulations
- http response code
- response time
Rate of errors can be controlled over a REST API (control plane)

Introduce response code errors

example request: curl http://localhost:8080/control/error?errorratio=2 -X POST

errorratio	percentage	responsecode
1	100	200
2	98	200
3	97	200
4	96	200
5	95	200
6	94	200
7	93	200
8	92	200
9	91	200
10	90	200
11	89	200
12	88	200
13	87	200
14	86	200
15	83	200
16	83	200
17	80	200
18	80	200
25	75	200
33	66	200
50	50	200
100	0	200

Introduce response code errors

example request: curl http://localhost:8080/control/latency?latencyinms=1000

run server

set envs (not mandatory)
- export RES_RESPONSECODESUCCESS=200
- export RES_RESPONSECODEFAILURE=500
- export RES_RESPONSECODESUCCESSFAILURERATIO=50
make build-server
bin/rest-error-simulator-server
get the data curl localhost:8080/best-tools
set the control curl localhost:8080/control/error?errorratio=50
get the metrics curl localhost:8080/metrics

run client

set envs (not mandatory)
- export RES_REQUESTFREQUENCYINSEC=1
- export RES_ENDPOINT=http://rest-error-simulator.com
make build-client
bin/rest-error-simulator-client
set the control curl localhost:8080/control?frequency=3