quick-debug

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What Problem To Solve

As the k8s becomes more and more popular, most projects are deployed in k8s, and so is the development environment.

But debugging is a little more troublesome, at least you need to replace the docker image (at this time you also need to commit your code, CICD build image, automatic or manual deployment, which needs much more time).

Timely feedback debugging (similar to front-end local debugging or local development environment) is more friendly to developers and will save a lot of time.

Application Scenario

• The development environment cannot be built locally, or the local development environment is not real enough
• Quickly debug the program by printing log
• Experiment with unfamiliar lib and check its running results
• Quickly understand the operation of a program
• Develop, debug and self-test at the same time

Principle

The principle is relatively simple. The image of the development environment needs to contain the quick-debug executable file, and the actual service is started by quick-debug.

After the program is compiled locally (for example, add some debug logs), upload it to the corresponding pod through the exposed node port, restart the service, and achieve the purpose of fast debugging.

Tool Command

quick-debug --help

Usage: quick-debug [Options] exec-args [real exec args]

Examples:
  quick-debug --exec-port 60006 --exec-path /your/exec/file/path exec-args --arg1 val1 --arg2 val2

Options:
  -disable-exec-log-file
    	disable exec log to file (when disable, you can't using TailLog API)
  -exec-path string
    	exec file path (absolute path)
  -exec-port int
    	exec file server port (Cannot be duplicated with real exec service) (default 60006)

quick-debug-client --help

NAME:
   quick-debug - quick debug program running in the k8s pod

USAGE:
   quick-debug-client [global options] command [command options] [arguments...]

COMMANDS:
   upload   uploads a file
   taillog  tail log program
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --help, -h  show help (default: false)

Effect

Before Use

Code modification, git submission, CICD generation image (or manual build image), automatic or manual replacement of remote k8s container image, use kubectl or container platform to view logs.

After Use

You can directly modify the code on the local development machine, compile, run the program on the remote k8s, and view the log on the local machine.

Steps For Usage

Take https://github.com/chinaran/go-httpbin as an example, you can refer to example

Note: Your local network needs to be able to access the development k8s cluster, this tool can only be used in the development environment.

0. Install quick-debug and quick-debug-client

git clone https://github.com/chinaran/quick-debug.git $GOPATH/src/github.com/chinaran/quick-debug/
cd $GOPATH/src/github.com/chinaran/quick-debug/
make install

1. Docker image contains /usr/local/bin/quick-debug

The following methods can be used:

• After local compilation, copy to the image when building
• Take ghcr.io/chinaran/quick-debug:0.2-alpine3.13 as the base image
• Similar to docker build example, copy quick-debug to the image

2. Deployment update command and args

        command:
          - quick-debug
          - --exec-path=/bin/go-httpbin # your exec path in docker
          - exec-args
        args: # orginal args
          - -port
          - "80"
          - -response-delay
          - 10ms

The final execution command of go-httpbin pod: quick-debug --exec-path=/bin/go-httpbin exec-args -port 80 -response-delay 10ms

The original command before go-httpbin pod modification: /bin/go-httpbin -port 80 -response-delay 10ms

3. Deploy NodePort Service (default port 60006)

Among them, nodePort is best fixed (random ones are fine)

kubectl apply -f - <
   
apiVersion: v1
kind: Service
metadata:
  name: {your-name}-nodeport
  namespace: {your-namespace}
spec:
  ports:
  - name: quick-deubg
    nodePort: {32101}
    port: 60006
    protocol: TCP
    targetPort: 60006
  selector:
    {your-selector-key}: {your-selector-value}
  type: NodePort
EOF

4. Compile the executable program locally, use quick-debug-client to upload the program and view its running log

# Compile the executable file
CGO_ENABLED=0 GOOS=linux go build -o /tmp/go-httpbin ./cmd/go-httpbin
# upx compression
upx -1 /tmp/go-httpbin
# Upload to remote k8s pod
quick-debug-client upload --addr {your-node-ip}:{your-node-port} --file {your-program-path}
# View remote k8s pod running logs locally
quick-debug-client taillog --addr {your-node-ip}:{your-node-port}

Golang can use shell fucntion to quickly execute corresponding commands (binaries generated in other languages ​​can also refer to this script)