Adding tcp logger.

[Akayeshmantha]

Summary

Adding support to tcp logger plugin.

Full changelog

Started working on tcp logger plugin

Referring these 2 repos :- https://github.com/openresty/lua-nginx-module#udpsocksetpeername
https://github.com/fluent/fluent-logger-node

I am more familiar with node.js so I thought it would help me. to understand the flow

Issues resolved

Fix #1220

[Akayeshmantha]

Hi @membphis @moonming

I completed the tcp logger but am getting below error in a unit test (test 5 access).

Failed test 'TEST 5: access - pattern "[error]" should not match any line in error.log but matches line "2020/03/11 09:41:17 [error] 26326\#26326: *21 [lua] tcp-logger.lua:61: failed to connect to TCP server: host[127.0.0.1] port[2001] connection refused, context: ngx.timer, client: 127.0.0.1, server: 0.0.0.0:1984" (req 0)

Any thoughts am actually blocked here

[moonming]

@Akayeshmantha the test case 5 will connect tcp log server 127.0.0.1:5044, which not exist, so it will fail.
you can mock tcp log server like this: https://github.com/apache/incubator-apisix/blob/master/t/APISIX.pm#L107

[Akayeshmantha]

Finally thanks @moonming @membphis . It's ready to review

[moonming]

need add plugin doc and README.md.

[Akayeshmantha]

@moonming added thanks.

[Akayeshmantha]

@moonming added the readme file and the document.

[Akayeshmantha]

@membphis @moonming can we merge this PR. If the read me doc is ok I can add udp plugin readme as well.

[membphis]

merged, many thx