IBM Client Developer Advocacy App Modernization Series

Lab - Build and run a WebSphere Liberty app with Docker

Overview

The lab illustrates how to build a simple WebSphere Liberty app with Docker

Step 1: Logon into the Web terminal

1.1 Login into your terminal environment with the URL and credentials provided by your instructor

Step 2: Create unique port number for your instance of Liberty

2.1 Run the following command to set an environment variable for a unique port based on your user identifier from the instructor (e.g. For example if your user id is user020 your port number should be 30020 ie 020 appended to 30)

 export LIBERTYPORT=30NNN

Step 3: Create unique name for your Liberty image

3.1 Run the following command to set an environment variable for a unique image name based on your user identifier from the instructor (e.g. For example if your user id is user020 your image name should be liberty-user020)

 export LIBERTYIMG=liberty-userNNN

Step 4: Clone the sample app repo

4.1 From the client terminal window clone the following Git repo with the app used in this lab

 git clone https://github.com/IBMAppModernization/liberty-hello-world-app.git
 cd liberty-hello-world-app

Step 5: Build a Docker image for the app

5.1 From the client terminal window build the Docker image.

 docker build --no-cache -t $LIBERTYIMG .

Step 6: Run the image for the app

6.1 From the client terminal window run the Docker image.

 docker run  --name $LIBERTYIMG -d  -p $LIBERTYPORT:9080  $LIBERTYIMG

Step 7: Test the running image

7.1 From the client terminal window test the Docker image. Verify that the curl command returns Hello World

 curl 127.0.0.1:$LIBERTYPORT/hello

Step 8: Inspect the running image

8.1 From the client terminal window get a shell inside your running container.

 docker exec -it $LIBERTYIMG bash

8.2 Verify that your command prompt changes to bash-4.2$ indicating that you are in a bash sheel in your running container

8.3 Look at the Liberty server logs

   cat /logs/messages.log

Verify that the log ends with something like the following (indicating that the application's single servlet initialized correctly):

 [12/4/19 12:54:40:566 UTC] 00000038 com.ibm.ws.webcontainer.servlet   I SRVE0242I: [hw-web] [/] [HelloWorldServlet]: Initialization successful.

8.4 Look at your server.xml file

 cat /config/server.xml

Verify that the line is loading your app:

  <webApplication contextRoot="/" location="hw-web.war" />

8.5 Look at the folder that contains all the installed applications

  ls -l /opt/ibm/wlp/usr/servers/defaultServer/apps

Verify that the your app is the only one installed:

  -rw-r--r-- 1 root root 4952 Dec  3 13:42 hw-web.war

8.6 Look at the running processes in the container

 ps -ef

Verify that Liberty, your bash shell and the ps command are the only processes that appear:

  UID        PID  PPID  C STIME TTY          TIME CMD
  default      1     0  2 12:54 ?        00:00:28 /opt/ibm/java/jre/bin/java -java
  default    141     0  0 12:55 pts/0    00:00:00 bash
  default   1038   141  0 13:13 pts/0    00:00:00 ps -ef

8.7 Exit the container shell

 exit

Cleanup

Run the following commands to cleanup (note: you can copy all the commands at once and post them into your command window)

 docker stop $LIBERTYIMG
 docker rm $LIBERTYIMG