🏩 👩‍🔧 🧢 Creación de imágenes de Docker optimizadas para una aplicación Spring Boot ☺️ 🎅🏾 👩🏻‍🎤

Los contenedores se han convertido en el medio preferido para empaquetar una aplicación con todas sus dependencias de software y sistema operativo, y luego entregarlas a diferentes entornos.

Este artículo explora las diferentes formas de contener su aplicación Spring Boot:

construir una imagen de Docker usando un Dockerfile,
construir una imagen OCI desde la fuente usando Cloud-Native Buildpack,
y optimizar la imagen en tiempo de ejecución dividiendo los archivos JAR en diferentes niveles utilizando herramientas en capas.

Código de muestra

Este artículo va acompañado de un código de trabajo de muestra en GitHub .

Terminología de contenedores

Comenzaremos con la terminología de contenedores utilizada en el artículo:

Imagen de contenedor : un archivo de un formato específico. Convertimos nuestra aplicación en una imagen de contenedor ejecutando la herramienta de compilación.
Contenedor : instancia ejecutable de una imagen de contenedor.
Motor de contenedor : un proceso demonio responsable de iniciar un contenedor.
Host de contenedor : la máquina host que ejecuta el motor de contenedor.
(Container registry): , .
OCI: Open Container Initiative (OCI) - , Linux Foundation. OCI , , , .

, . , .

2.3 Spring Boot OCI.

Docker - , Docker , Docker.

Docker Spring Boot , Docker.

JAR , Docker, JAR JRE .

Spring Spring Initializr web, lombok actuator. rest , API GET.

Docker

, Dockerfile:

FROM adoptopenjdk:11-jre-hotspot
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/application.jar"]

Docker , adoptopenjdk, JAR, , 8080 .

Maven Gradle. Maven:

mvn clean package

JAR- . JAR Docker Docker.

JAR Docker, docker build , Docker, :

docker build  -t usersignup:v1 .

docker images

usersignup , adoptopenjdk, Docker.

REPOSITORY          TAG                 SIZE
usersignup          v1                  249MB
adoptopenjdk        11-jre-hotspot      229MB

. dive, :

dive usersignup:v1

Dive:

, . .

Buildpack

(Buildpacks) - , « » (PAAS) . Heroku 2011 Cloud Foundry, Google App Engine, Gitlab, Knative .

Buildpack , (builder) , builder.

. Cloud-Native Buildpacks , OCI, , Docker.

Spring Boot

Spring Boot OCI Buildpack. bootBuildImage (Gradle) spring-boot:build-image (Maven) Docker.

, Docker, image tag:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
    <image>
      <name>docker.io/pratikdas/${project.artifactId}:v1</name>
    </image>
  </configuration>
</plugin>

Maven build-image . Docker.

mvn spring-boot:build-image

[INFO] --- spring-boot-maven-plugin:2.3.3.RELEASE:build-image (default-cli) @ usersignup ---
[INFO] Building image 'docker.io/pratikdas/usersignup:v1'
[INFO] 
[INFO]  > Pulling builder image 'gcr.io/paketo-buildpacks/builder:base-platform-api-0.3' 0%
.
.
.. [creator]     Adding label 'org.springframework.boot.version'
.. [creator]     *** Images (c311fe74ec73):
.. [creator]           docker.io/pratikdas/usersignup:v1
[INFO] 
[INFO] Successfully built image 'docker.io/pratikdas/usersignup:v1'

, paketo Cloud-Native buildpack OCI. , , Docker, :

docker images

REPOSITORY                             SIZE
paketobuildpacks/run                  84.3MB
gcr.io/paketo-buildpacks/builder      652MB
pratikdas/usersignup                  257MB

Jib

Jib - Google, .

jib-maven-plugin pom.xml:

      <plugin>
        <groupId>com.google.cloud.tools</groupId>
        <artifactId>jib-maven-plugin</artifactId>
        <version>2.5.2</version>
      </plugin>

Jib Maven, . , Docker:

mvn compile jib:build -Dimage=<docker registry name>/usersignup:v1

Maven :

[INFO] Containerizing application to pratikdas/usersignup:v1...
.
.
[INFO] Container entrypoint set to [java, -cp, /app/resources:/app/classes:/app/libs/*, io.pratik.users.UsersignupApplication]
[INFO] 
[INFO] Built and pushed image as pratikdas/usersignup:v1
[INFO] Executing tasks:
[INFO] [==============================] 100.0% complete

, .

: , . . CI.
: .

Docker , Dockerfile. . Docker , .

Spring Boot « JAR» . JAR, , JAR. , . Spring Framework.

Spring Framework.

, JAR-, -.

, :

, Spring Boot.

Spring Boot Buildpack

Spring Boot 2.3 JAR- . , Spring Boot Maven:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
    <layers>
      <enabled>true</enabled>
    </layers>
  </configuration> 
</plugin>

Buildpack, Docker .

build-image Maven :

mvn spring-boot:build-image

Dive, , , ( ) , JAR:

Spring Boot Docker

Maven Gradle JAR Docker Docker.

Docker, .

JAR Maven :

META-INF/
.
BOOT-INF/lib/
.
BOOT-INF/lib/spring-boot-jarmode-layertools-2.3.3.RELEASE.jar
BOOT-INF/classpath.idx
BOOT-INF/layers.idx

JAR spring-boot-jarmode-layertools layersfle.idx. JAR- , .

JAR, -Djarmode=layertools spring-boot-jarmode-layertoolsJAR :

java -Djarmode=layertools -jar target/usersignup-0.0.1-SNAPSHOT.jar

, :

Usage:
  java -Djarmode=layertools -jar usersignup-0.0.1-SNAPSHOT.jar

Available commands:
  list     List layers from the jar that can be extracted
  extract  Extracts layers from the jar for image creation
  help     Help about any command

list, extract help help . list:

java -Djarmode=layertools -jar target/usersignup-0.0.1-SNAPSHOT.jar list

dependencies
spring-boot-loader
snapshot-dependencies
application

, .


`dependencies`	, SNAPSHOT
`spring-boot-loader`	JAR
`snapshot-dependencies`	, SNAPSHOT
`application`

layers.idx , Docker. , . , - .

,

, , . , .

Docker :

# the first stage of our build will extract the layers
FROM adoptopenjdk:14-jre-hotspot as builder
WORKDIR application
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN java -Djarmode=layertools -jar application.jar extract

# the second stage of our build will copy the extracted layers
FROM adoptopenjdk:14-jre-hotspot
WORKDIR application
COPY --from=builder application/dependencies/ ./
COPY --from=builder application/spring-boot-loader/ ./
COPY --from=builder application/snapshot-dependencies/ ./
COPY --from=builder application/application/ ./
ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]

- Dockerfile2.

Docker :

docker build -f Dockerfile2 -t usersignup:v1 .

Sending build context to Docker daemon  20.41MB
Step 1/12 : FROM adoptopenjdk:14-jre-hotspot as builder
14-jre-hotspot: Pulling from library/adoptopenjdk
.
.
Successfully built a9ebf6970841
Successfully tagged userssignup:v1

, Docker , .

, Dive, , Docker. Dive:

dive userssignup:v1

, , , 11 , .

, , , yml layers.idx:

- "dependencies":
  - "BOOT-INF/lib/"
- "spring-boot-loader":
  - "org/"
- "snapshot-dependencies":
- "custom-dependencies":
  - "io/myorg/"
- "application":
  - "BOOT-INF/classes/"
  - "BOOT-INF/classpath.idx"
  - "BOOT-INF/layers.idx"
  - "META-INF/"

layers.idx , io.myorg , .

Cloud-Native Buildpacks . Docker : JAR, , Docker.

, , , , .

, Github .

, .

docker system prune -a

Docker:

docker build -f <Docker file name> -t <tag> .

( Dockerfile):

mvn spring-boot:build-image

. JAR- , spring-boot-maven-plugin:

java -Djarmode=layertools -jar application.jar list