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Skaffolding develoment in golang

THis is a sample project in golang that demonstarate building for source debugging and multisage container build. The sample code implements a http where client can send command to list pods in a namespace. The app accedd the k8s API server, and we'll attach a debugger to set breakpoits and debug live code.

Prerequisit on local machine

  • golang 1.18
  • docker
  • kind
  • kubectl
# For MAC, the prereq is installed with kind [homebrew](https://brew.sh)
brew install go
brew install kind
brew install kubectl

General

List available make comands

make help

help             Display this help.
clean-docker     Clean dangeling docker images
build-image      Build Container Image
push-image       Push Container Image
run              Run container in docker
exec             exec to container started by Docker
create-cluster   Create Kind Cluster
destroy-cluster  Destroy Kind Cluster
load-image       Load Docker image in Kind
deploy           Deploy pod to kinf
undeploy         Undeploy pod
debug-pod        Debug pod in kind with dlv
send-curl        Send Curl command to pod

Start Kind Cluster

make create-cluster

Inspect Dockerfile, Build and Push Docker image

Note the build produces two images. One with code and debug tools and one for release

$ make build-image

$ docker images
localhost:5000/sample-k8s-client         0.0.1     10fe72045f59   11 minutes ago      40.9MB
localhost:5000/sample-k8s-client-debug   0.0.1     3c8ed9984aa5   11 minutes ago      1.42GB

Deploy Pod, and ensure it's running

make deploy
kubectl get pod

Attach dlv debugger

The sample service is running as main process in the pod with pid 1.
The dlv is included in the debug image and we can start dlv and attach to the main program with

kubectl exec -it my-pod dlv attach 1
alt.
make debug-pod

This attached dlv to the service and anters a debug mode.

Set breakpoint in the the function that access to the k8s API

# set breakpoint
b client.ListPods

# list code
l client.ListPods

# resume execution
c

Trigger the API with curl to hit breakpoint

The pod has a scrip /debug.sh that sends a curl request to list pods in kube-system namespace

kubectl exec -it my-pod /debug.sh

alt.
make send-curl

dlv commands