Containerization is the process of packaging software code, its required dependencies, configurations, and other detail to be easily deployed in the same or another computing environment. containerization is the encapsulation of an application and its required environment. To package up apps so they could be run on production systems. To do this we need some kind of virtualization layer that would allow anything to be run. Heroku was one of the first to tackle this and they used a Linux virtualization system called "lxc" - short for Linux Containers. A bit later a Heroku competitor named dotCloud was trying to tackle similar problems and went a different route which ultimately led to Docker, a standard way to create and run containers across platforms including Windows, Mac, Linux, Kubernetes.
- Dockerfile
- Buildpacks
- JIB
- Simple - As developer need not maintain Dockerfile and all ways to handle it. Dev could focus majorly on the application functionality and the Gradle/Maven Jib plugin will do the rest. Actually, we don't even have to have docker installed to create and publish the docker images ourselves.
- Fast - As JIB takes advantage of caching image layers. Deploy your changes fast. Jib separates your application into multiple layers, splitting dependencies from classes. Now you don't have to wait for Docker to rebuild your entire Java application - just deploy the layers that changed.
- Reproducible - Rebuilding your container image with the same contents always generates the same image. Never trigger an unnecessary update again.
Note: It requires gradle version 5.1. If your version is less than 5.1, please run gradle wrapper --gradle-version=5.1 first.
$ cd demo/
$ ./gradlew jib
> Task :jib
Containerizing application to ritreshgirdhar/jib-demo:1.0.0...
Base image 'adoptopenjdk:8-jre' does not use a specific image digest - build may not be reproducible
Using credentials from Docker config (/Users/ritgirdh/.docker/config.json) for ritreshgirdhar/jib-demo:1.0.0
The base image requires auth. Trying again for adoptopenjdk:8-jre...
Using credentials from Docker config (/Users/ritgirdh/.docker/config.json) for adoptopenjdk:8-jre
Using base image with digest: sha256:5b55ef54f25717b7680db93625a6969d52d5608a0d7984f007ad291b82d531e8
Container entrypoint set to [java, -cp, /app/resources:/app/classes:/app/libs/*, com.example.demo.DemoApplication]
Built and pushed image as ritreshgirdhar/jib-demo:1.0.0
Executing tasks:
[============================ ] 91.7% complete
> launching layer pushers
BUILD SUCCESSFUL in 11s
$ dive ritreshgirdhar/jib-demo:1.0.0
Image Source: docker://ritreshgirdhar/jib-demo:1.0.0
Fetching image... (this can take a while for large images)
Analyzing image...
Building cache...
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
You will not find docker image. As, JIB directly push the image to the registry. It doesn't require docker to be installed on the developer machine unlike native containerization approach. Isn't it cool!
$ docker pull ritreshgirdhar/jib-demo:1.0.0
1.0.0: Pulling from ritreshgirdhar/jib-demo
345e3491a907: Pull complete
57671312ef6f: Pull complete
5e9250ddb7d0: Pull complete
592ec2d7c137: Pull complete
be75864d3169: Pull complete
5bd29a5522bd: Pull complete
db04461d3510: Pull complete
305a053a7af7: Pull complete
Digest: sha256:331a5a98492365fa98079ff1d2b615ddd4cb578a9b290ca5ac09f6bfd3ffff80
Status: Downloaded newer image for ritreshgirdhar/jib-demo:1.0.0
docker.io/ritreshgirdhar/jib-demo:1.0.0
$ docker run -p8080:8080 ritreshgirdhar/jib-demo:1.0.0
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.5.0)
2021-05-30 09:07:19.586 INFO 1 --- [ main] com.example.demo.DemoApplication : Starting DemoApplication using Java 1.8.0_292 on 100c84485a32 with PID 1 (/app/classes started by root in /)
2021-05-30 09:07:19.592 INFO 1 --- [ main] com.example.demo.DemoApplication : No active profile set, falling back to default profiles: default
2021-05-30 09:07:21.637 INFO 1 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2021-05-30 09:07:21.665 INFO 1 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2021-05-30 09:07:21.665 INFO 1 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.46]
2021-05-30 09:07:21.795 INFO 1 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2021-05-30 09:07:21.796 INFO 1 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2093 ms
2021-05-30 09:07:22.348 INFO 1 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-05-30 09:07:22.364 INFO 1 --- [ main] com.example.demo.DemoApplication : Started DemoApplication in 3.475 seconds (JVM running for 4.111)
2021-05-30 09:07:22.367 INFO 1 --- [ main] o.s.b.a.ApplicationAvailabilityBean : Application availability state LivenessState changed to CORRECT
2021-05-30 09:07:22.370 INFO 1 --- [ main] o.s.b.a.ApplicationAvailabilityBean : Application availability state ReadinessState changed to ACCEPTING_TRAFFIC
$ curl -i http://localhost:8080/
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 37
Date: Sun, 30 May 2021 09:14:20 GMT
Welcome to Jib containerization demo
$ curl -i http://localhost:8080/hostname
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 22
Date: Sun, 30 May 2021 09:13:40 GMT
Welcome tof993e5810002
Happy learning !