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Installing the Docker environment

This process applies the WhaTap monitoring agent to the Go application running on the Docker container and packages the container image as follows.

Download agent​

Install the whatap-agent package when building your Go application docker image.

x64
RUN wget https://s3.ap-northeast-2.amazonaws.com/repo.whatap.io/alpine/x86_64/whatap-agent.tar.gz
RUN tar -xvzf whatap-agent.tar.gz -C /

Agent CONFIG.​

Create the whatap.conf file in which WhaTap's access key and server IP address have been set in the user application execution path. If you use a specific path, you can set it with the WHATAP_HOME environment variable.

whatap.conf
RUN echo "accesskey={Access Key}" >> whatap.conf 
RUN echo "whatap.server.host={Collection Server IP Address}" >> whatap.conf
Note

Be careful not to expose the access key to images that are in Docker Public status.

Setting the WHATAP_HOME variable​

You can set the whatap.conf path as the WHATAP_HOME variable. Create the WHATAP_HOME path first. Add the WHATAP_HOME setting before the application startup command.

mkdir ./whatap_home
echo "license={Access Key}" >> ./whatap_home/whatap.conf
echo "whatap.server.host={Collection Server IP Address}" >> ./whatap_home/whatap.conf

# run application
WHATAP_HOME=./whatap_home ./app

Configuring the Go library​

Add the github.com/whatap/go-api package to the Go application source code.

go get github.com/whatap/go-api

Configure for initialization and shutdown with the trace.Init() and trace.Shutdown() functions. Set the startup and end for transactions with the trace.Start() and trace.End() functions.

Go
import "github.com/whatap/go-api/trace"

func main(){
    trace.Init(nil)
    //It must be executed before closing the app.    
    defer trace.Shutdown()    

    ctx, _ := trace.Start(context.Background(), "Start Tx")

    ...

    trace.End(ctx, err)
}
Note

For more information about the library configuration, see the following.

Configuring the container environment variables​

After building Docker, set container environment variables in the Kubernetes environment. Add the following items in the yaml file for releasing the application.

env:
- name: NODE_IP
  valueFrom: {fieldRef: {fieldPath: status.hostIP}}
- name: NODE_NAME
  valueFrom: {fieldRef: {fieldPath: spec.nodeName}}
- name: POD_NAME
  valueFrom: {fieldRef: {fieldPath: metadata.name}}

See the following example:

apiVersion: v1
kind: Pod
metadata:
  name: # Pod Name
  labels: # Pod Labels
spec:
  containers:
    env:
    - name: NODE_IP
      valueFrom: {fieldRef: {fieldPath: status.hostIP}}
    - name: NODE_NAME
      valueFrom: {fieldRef: {fieldPath: spec.nodeName}}
    - name: POD_NAME
      valueFrom: {fieldRef: {fieldPath: metadata.name}}
Note

Roles of environment variables

  • NODE_IP: Collects the IP address of the node where the current Pod has been hosted.

  • NODE_NAME: Collects the name of the node where the current Pod is running.

  • POD_NAME: Collects the name of the current Pod.

Running the agent​

Add the whatap-agent startup command before the application startup command.

sh -c "/usr/whatap/agent/whatap-agent start && [application startup command]"

Execute the following command to check whether the WhaTap service has been run normally. When the application server runs, it begins collecting monitoring information.

ps -ef | grep whatap_agent

Checking the agent installation​

To check whether the agent has been installed, go to Dashboard > Application service dashboard.

If you have manually installed the downloaded file but cannot see the agent in Dashboard, check the following.

  • Execute the command, ps -ef | grep whatap_agent in the container, and then check whether the agent options have been applied properly.

  • Check the WHATAP_HOME/logs of the container or the logs directory of the application execution path. The file name of the agent log is displayed as logs/{boot or install}-yyyymmdd.log.