1.why

kubernetes是使用go語言編寫的竹祷，對于很多同學(xué)來說介蛉，可能對這種語言機制不甚熟悉。掌握調(diào)試方法溶褪，一方面能夠精準(zhǔn)定位問題，另一方面對學(xué)習(xí)相關(guān)語言也有反向促進機制践险。摩刀不誤砍柴功猿妈。只要有源碼吹菱，任何問題都是可以解決的，剩下的只是時間問題彭则。

2.準(zhǔn)備工作

1. 安裝delve
   delve是目前最方便用于調(diào)試golang的工具鳍刷，安裝delve有兩種方法:

• 使用go命令:

go get -u github.com/derekparker/delve/cmd/dlv

• 使用源碼

https://github.com/derekparker/delve
make install

2.編譯kubernetes組件

• 通過make help查看如何編譯帶調(diào)試信息的kubernetes組件

[newcent@localhost kubernetes-1.9.2]$ make help
--------------------------------------------------------------------------------
all
# Build code.
#
# Args:
#   WHAT: Directory names to build.  If any of these directories has a 'main'
#     package, the build will produce executable files under _output/go/bin.
#     If not specified, "everything" will be built.
#   GOFLAGS: Extra flags to pass to 'go' when building.
#   GOLDFLAGS: Extra linking flags passed to 'go' when building.
#   GOGCFLAGS: Additional go compile flags passed to 'go' when building.
#
# Example:
#   make
#   make all
#   make all WHAT=cmd/kubelet GOFLAGS=-v
#   make all GOGCFLAGS="-N -l"
#     Note: Use the -N -l options to disable compiler optimizations an inlining.
#           Using these build options allows you to subsequently use source
#           debugging tools like delve.
---------------------------------------------------------------------------------
......

• 使用make all GOGCFLAGS="-N -l"編譯kubernetes組件

3.調(diào)試kubelet

• 將編譯kubelet拷貝到相應(yīng)的node上
• 在node上通過dlv啟動kubelet

 dlv exec ./kubelet --headless -l 192.168.122.12:1234 -- --logtostderr=true --v=0 --allow-privileged=false --address=0.0.0.0 --hostname-override=node1 --pod-infra-container-image=gcr.io/google_ctainers/pause-amd64:3.0 --kubeconfig=/etc/kubernetes/kubelet.kubeconfig --cgroup-driver=systemd

--headless -l 192.168.122.12:1234指定啟動一個調(diào)試server端，因為編譯kubernetes組件往往不會在node上編譯俯抖，node上也沒有相應(yīng)的源碼输瓜，通過這一機制，可以在編譯節(jié)點上啟動dlv client芬萍，調(diào)試相關(guān)代碼尤揣。

• 在編譯節(jié)點上連接server端

[newcent@localhost kubernetes-1.9.2]$ dlv connect 192.168.122.12:1234
Type 'help' for list of commands.
(dlv) b main.main
Breakpoint 1 set at 0x394496b for main.main() ./_output/local/go/src/k8s.io/kubernetes/cmd/kubelet/kubelet.go:44
(dlv) c
> main.main() ./_output/local/go/src/k8s.io/kubernetes/cmd/kubelet/kubelet.go:44 (hits goroutine(1):1 total:1) (PC: 0x394496b)
Warning: debugging optimized function
Warning: listing may not match stale executable
    39: func die(err error) {
    40:     fmt.Fprintf(os.Stderr, "error: %v\n", err)
    41:     os.Exit(1)
    42: }
    43: 
=>  44: func main() {
    45:     // construct KubeletFlags object and register command line flags mapping
    46:     kubeletFlags := options.NewKubeletFlags()
    47:     kubeletFlags.AddFlags(pflag.CommandLine)
    48: 
    49:     fmt.Printf("args: %s\n", os.Args[0])
(dlv) 

4.delve使用方法(附)