Feature reload cmd

[Jun10ng]

Issues associated with this PR

支持Mosn reload命令(#1680)

mosn reload
or
mosn reload -c config_path

[Jun10ng]

@doujiang24
@nejisama

[codecov]

Codecov Report

Base: 60.56% // Head: 60.52% // Decreases project coverage by -0.04% ⚠️

Coverage data is based on head (bafdd8e) compared to base (7609947).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2030      +/-   ##
==========================================
- Coverage   60.56%   60.52%   -0.05%     
==========================================
  Files         422      422              
  Lines       36629    36688      +59     
==========================================
+ Hits        22184    22205      +21     
- Misses      12263    12302      +39     
+ Partials     2182     2181       -1     

Impacted Files	Coverage Δ
pkg/mosn/mosn.go	35.56% <ø> (ø)
pkg/stagemanager/stage_manager.go	38.22% <0.00%> (-6.58%)	⬇️
pkg/router/types.go	48.19% <0.00%> (-2.45%)	⬇️
pkg/protocol/api.go	76.00% <0.00%> (ø)
pkg/config/v2/route.go	74.41% <0.00%> (ø)
pkg/router/base_rule.go	78.84% <0.00%> (+0.13%)	⬆️
pkg/module/http2/server.go	81.85% <0.00%> (+0.29%)	⬆️
pkg/module/http2/transport.go	78.91% <0.00%> (+0.43%)	⬆️
pkg/metrics/shm/zone.go	69.23% <0.00%> (+2.56%)	⬆️
pkg/proxy/retrystate.go	76.27% <0.00%> (+2.68%)	⬆️
... and 1 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[nejisama]

目前的reload是靠向旧进程发送HUP信号触发热升级流程执行reload，但是MOSN是可以通过配置关闭热升级的，有没有测试过这种情况下，reload是什么结果？

[nejisama]

补充对应的文档到MOSN官网，需要说明各种细节。
比如mosn reload -c config.json 并不是用config.json去reload，还是用原来start的配置进行reload的等

[Jun10ng]

目前的reload是靠向旧进程发送HUP信号触发热升级流程执行reload，但是MOSN是可以通过配置关闭热升级的，有没有测试过这种情况下，reload是什么结果？

如果打开热升级执行 reload的话，新进程会向老mosn进程向发热升级信号，老进程会报错
"[server] SIGHUP received: current state expected running while got 13"，最终导致无法执行reload，这个问题我在最新的commit内修复了，执行reload的时候不发送热升级信号。

[Jun10ng]

补充对应的文档到MOSN官网，需要说明各种细节。 比如mosn reload -c config.json 并不是用config.json去reload，还是用原来start的配置进行reload的等

好的，等PR合进好，我再提个PR到mosn.io

[Jun10ng]

Error: -01 07:41:19,967 [ERROR] [config] network filter create failed, type:tcp_proxy, error: unsupported network filter type: tcp_proxy
Error: -01 07:41:19,967 [ERROR] [config] network filter factories len is 0, listener: &{ListenerConfig:{Name:0.0.0.0_80 Type: AddrConfig: BindToPort:false Network: UseOriginalDst:false 

这个CI 失败看起来不是我提交的代码影响的。

[doujiang24]

istio/istio152/main/control.go:21:2: imported and not used: "fmt"

https://github.com/mosn/mosn/runs/8153277565?check_suite_focus=true#step:5:222
@Jun10ng 看起来是这个错误呢