Creating a simple Spring Boot application and Docker deployment. 

This documentation illustrates the simple ways of deploying a spring boot application on a docker container.  This application is just a simple one with no DB interaction. We will cover the deployment of Spring boot application with DB in other post 

PreRequisite: 

We need to have the following softwares. 

Operating System :	Window/Linux (CENTOS-7 is used during this course)
Container	Docker (Should be installed)
Application	Spring boot application (CRUD Operation)

Application: 

We have a sample application named billing and is on Spring boot. This is a very simple application and does not have any interaction with any other downstream system. 

This application have the following api’s :

API	Method	Usage
\bill\api\create	PUT	Create a new objects
\bill\api\update	POST	Update the existing objects
\bill\api\get	GET	Fetch all the objects
\bill\api\get\{id}	GET	Fetch the specified objects

We will check these API after the deployment on docker. 

Technical Details:

Spring boot Project: 

We have a sample application on Springboot, which is a simple application with no interaction with downstream systems like DB. The package structure for this project looks like the below. 

Let’s discuss some files which are related to containerisation. 

Dockerfile: This file is used to create an image for the project. This image is used to deploy on the containerised environment, like docker, rocket etc. This file should be present in the root folder of the project. Let’s check the content of it. 

Lets check few more options of instructions in file. Dockerfie is a file that contains the Instruction and argument and must start with FROM instruction. This is not case sensitive, but the convention is for instructions should be in uppercase.

WORKDIR: This instruction is used to switch to the directory specified. Then this directory is used to copy files, run commands in that container. This also help to create a new directory, which is used for building the image, copy code and jar file from local system. Example: WORKDIR /opt/apps

ENV: This is used to set the environment variable of docker image. with the help of this attribute we can override the values exposed as environment variable. Example: ENV variableName=variableValue

ADD: This instruction also help to copy the files into container from host system. It is just like a copy instruction with one more benefit, that it can copy the files from remote locations as well. You can define any URL as source. So it fetch the file from remote and copy it to container.

RUN: This instruction is used to run the command on container. Example: RUN ls -ltr RUN chown user:group dir

ENTRYPOINT: This instruction is used to configure the container that will run as an executable. There could be multiple command can be added as an instruction, or any shell script to execute. Example: ENTRYPOINT [“executable”, “param1”, “param2”, … , “paramN”]

Building Image

Let’s build the image of a billing application.  Command: docker build -t <USER_ID>/<IMAGE_NAME> .  Example: docker build -t pandeych009/itlogiclab-bill-image .

The above command produces the following result. 

There are some other flavours of the build command. 

• If we have to provide a Dockerfile then the following command would work. 
  • docker build – < Dockerfile
  • docker build . -f Dockerfile -t <IMAGE-NAME>

Running application on Container

Let’s start to run the application with the use of docker commands. Let’s check the simple command first.  Command: docker run <image-name>  <options> Example: docker run -p localhost:80:20002 -it pandeych009/itlogiclab-bill-image

We have used few options here and they are used for 

Options	Description	Explanation
		.
-i  –interactive		This operation termin
-t –tty		Allocate a pseudo TTY
-p –publish	0.0.0.0:80:20002	This option exposes the container’s port to the host port.  Application starts at the PORT 20002 at the container.  This port is accessible for the client on 80 port of the host for all the IP’s

With this the container starts successfully. Let’s check the status of it. 

Validate container state: 

To validate the container we need to run the following command.

Command: docker ps

Test Application on container

Fetch Record (GET Operation)

To test the container we need to fire the Curl command in terminal, or we can use postman as well 

API Call : http:\\localhost:80\bill\api\get Command: Use Curl command as curl http:\\localhost:80\bill\api\get

With this command we will get the following output: 

Add Record (PUT Operation)

API Call: http://localhost:80/bill/api/add Command: Use Curl command as mention below.

curl -X PUT -H “Content-Type: application/json” -d ‘{“customerId”:20003,”invoiceNo”:”Invoice_937082346397587239″,”billAmount”:9.3708236E17,”date”:”2022-10-09T07:16:31.635Z”,”orderId”:937082346397607240,”amount”:937082346397607241,”status”:”PENDING”,”billInfoList”:[{“billInfoId”:-319915949760543233,”invoiceNo”:null,”chargeName”:”My_Charge_-319915949760543233″,”chargeCost”:-1.59957982E17},{“billInfoId”:-7339925261522476103,”invoiceNo”:null,”chargeName”:”My_Charge_-7339925261522476103″,”chargeCost”:-3.66996256E18},{“billInfoId”:-4495016224261477917,”invoiceNo”:null,”chargeName”:”My_Charge_-4495016224261477917″,”chargeCost”:-2.24750814E18},{“billInfoId”:2432793819155524555,”invoiceNo”:null,”chargeName”:”My_Charge_2432793819155524555″,”chargeCost”:1.21639686E18},{“billInfoId”:-4476846372823844252,”invoiceNo”:null,”chargeName”:”My_Charge_-4476846372823844252″,”chargeCost”:-2.23842316E18},{“billInfoId”:2797949467354393091,”invoiceNo”:null,”chargeName”:”My_Charge_2797949467354393091″,”chargeCost”:1.39897475E18},{“billInfoId”:-6582284907281397716,”invoiceNo”:null,”chargeName”:”My_Charge_-6582284907281397716″,”chargeCost”:-3.29114232E18},{“billInfoId”:360364351120203589,”invoiceNo”:null,”chargeName”:”My_Charge_360364351120203589″,”chargeCost”:1.80182176E17},{“billInfoId”:1523579306349991233,”invoiceNo”:null,”chargeName”:”My_Charge_1523579306349991233″,”chargeCost”:7.6178962E17},{“billInfoId”:-2167995517030885175,”invoiceNo”:null,”chargeName”:”My_Charge_-2167995517030885175″,”chargeCost”:-1.08399772E18}]}’ http://localhost:80/bill/api/add

Update Record (Post Operation)

API Call: http://localhost:80/bill/api/update Command: Use Curl command as mention below.

curl -X PUT -H “Content-Type: application/json” -d ‘{“customerId”:20003,”invoiceNo”:”Invoice_937082346397587239″,”billAmount”:9.3708236E17,”date”:”2022-10-09T07:16:31.635Z”,”orderId”:937082346397607240,”amount”:937082346397607241,”status”:”PENDING”,”billInfoList”:[{“billInfoId”:-319915949760543233,”invoiceNo”:null,”chargeName”:”My_Charge_-319915949760543233″,”chargeCost”:-1.59957982E17},{“billInfoId”:-7339925261522476103,”invoiceNo”:null,”chargeName”:”My_Charge_-7339925261522476103″,”chargeCost”:-3.66996256E18},{“billInfoId”:-4495016224261477917,”invoiceNo”:null,”chargeName”:”My_Charge_-4495016224261477917″,”chargeCost”:-2.24750814E18},{“billInfoId”:2432793819155524555,”invoiceNo”:null,”chargeName”:”My_Charge_2432793819155524555″,”chargeCost”:1.21639686E18},{“billInfoId”:-4476846372823844252,”invoiceNo”:null,”chargeName”:”My_Charge_-4476846372823844252″,”chargeCost”:-2.23842316E18},{“billInfoId”:2797949467354393091,”invoiceNo”:null,”chargeName”:”My_Charge_2797949467354393091″,”chargeCost”:1.39897475E18},{“billInfoId”:-6582284907281397716,”invoiceNo”:null,”chargeName”:”My_Charge_-6582284907281397716″,”chargeCost”:-3.29114232E18},{“billInfoId”:360364351120203589,”invoiceNo”:null,”chargeName”:”My_Charge_360364351120203589″,”chargeCost”:1.80182176E17},{“billInfoId”:1523579306349991233,”invoiceNo”:null,”chargeName”:”My_Charge_1523579306349991233″,”chargeCost”:7.6178962E17},{“billInfoId”:-2167995517030885175,”invoiceNo”:null,”chargeName”:”My_Charge_-2167995517030885175″,”chargeCost”:-1.08399772E18}]}’ http://localhost:80/bill/api/add

Docker Compose:

Docker compose is a tool, which help to configure the deployment in a single configuration file. Consider an example if we have a complex application that interact with the multiple downstream system. If we deploy the system by running the docker commands makes this deployment tedious and cumbersome. We will see more details of docker compose in our upcoming blog.

Conclusion

Very basic steps for the beginner, how to deploy the application into the local docker environment. We will publish the another knowledge base, where this springboot application will interact with the mysql database and we see how to deploy this.