What is docker
Docker is a container platform delivered by a company named “Docker Inc.” Docker can be used by developers, operators and enterprise users to deliver and use packaged software. Docker has something called a container. Container can be a virtual machine (VM) in lay man’s terms, but still little different from VM. Container contains packaged software delivered in a way that it can be run isolated on a shared operating system. As per official definition – Unlike VMs, container does not bundle a full operating system – only libraries and settings required to make the software work are needed.
In this demo, we will use our spring boot application built throughout from Part I to Part VIII.
I am using Windows Platform Toolbox for docker to build my docker containers.
We will build a container with mysql database deployed and another container where we will deploy spring boot application. This spring boot application container will connect to mysql database container at runtime. The process is little complicated, but once you get your hands on docker container, it becomes very straight forward to understand. Also for this post, I will not explain anything about spring boot application. You should review all the previous posts I have written explaining how to build and deploy spring boot application on an embedded tomcat.
Building a docker container with mysql
Few things to remember
- Make sure your spring boot application is working with mysql database before you build a container.
- If your application contains user administration and password, make sure you have a super administrator whose password you can insert in database with password_hash. This is specifically true for the application we will be deploying in docker container.
For most standard applications (like mysql, java 8, spring-boot), there are number of images available in docker hub. When we will run our docker container for database, docker shell will pull the version of that application from the hub to build a container. We will not be creating any new or blank docker image. To run a docker container with mysql version 5.6, we will use below command.
- Name of our docker container is benefitsmysql.
- We are not using any password. This is not recommended for production code, I am just doing this for demo purposes.
- Database name is benefitsmysql.
- Also this database is running at port 3308 to 3306 of local host machine.
-d to tell Docker to daemonize the container and keep it running.
mysql:5.6 to download MySQL 5.6 Server image from Docker public repo
Once this is started, there are couple of ways you can verify if we are able to connect to this database or not.
Get the ip address of this container host with command
docker-machine ip . Now in mysql administrator workbench, access the mysql server with ip address and port 3308 and see if you can access the database.
Another way on docker shell terminal – use this command
docker exec -it benefitsmysql -l , this will connect you as a root to the shell where mysql is installed. And then you can use
mysql as regular command to access mysql.
To run our Spring boot application successfully, once you access mysql, create following tables:
Building a docker image for Spring Boot Application along with mysql
To dockerize my spring boot application, we will use a maven plugin to build a docker image.
I am passing dockerDirectory where Dockerfile will be stored to build our image. Also another change I have made to my original pom file, is that i have added packaging as jar.
I have also changed in my application.properties to point to mysql database container by updating database url with ipaddress of docker container.
My Dockerfile to build a docker image is as below:
Basically this will build a Benefits.jar using java 8 and will expose port 8443 that I can use to access my application.
Now build a new docker container image by using maven goal as
mvn clean package docker:build
To run the application
docker run -p 8443:8443 --name benefits --link benefitsmysql:mysql -d containerid
This will execute the jar built within that container. Important to note here is
--link as it links other container where we have mysql server deployed. So we are linking two containers and we will call the database from our spring boot application container. The same command can be used little differently to see the detail execution log as below
docker run -p 8443:8443 --name benefits --link benefitsmysql:mysql -it containerid
Executing the application
Once the application starts successfully, we will access our application with url
https://192.168.99.100:8443/home , this will look like below:
Another note – Make sure to update ip addess in all angular js references.
In this post, we showed how we can deploy Spring boot application connected to mysql on a docker container. Code for this post will be available on github repository here
To write my post, I used following references
- Connection refused error
- Spring Boot docker