Skip to content

Commit

Permalink
Merge branch '3.3.x'
Browse files Browse the repository at this point in the history
Closes gh-42114
  • Loading branch information
mhalbritter committed Sep 4, 2024
2 parents b05336d + 8d44fd5 commit 45cecf5
Show file tree
Hide file tree
Showing 3 changed files with 54 additions and 26 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,12 @@ This will cause the buildpack to do a training run of the application, save the

The Paketo Buildpack for Spring Boot https://github.com/paketo-buildpacks/spring-boot?tab=readme-ov-file#configuration[documentation] has information on other configuration options that can be enabled with builder environment variables, like `CDS_TRAINING_JAVA_TOOL_OPTIONS` that allows to override the default `JAVA_TOOL_OPTIONS`, only for the CDS training run.

[[howto.class-data-sharing.dockerfiles]]
== Packaging an Application Using CDS and Dockerfiles

If you don't want to use Cloud Native Buildpacks, it is also possible to use CDS with a `Dockerfile`.
For more information about that, please see the xref:reference:packaging/container-images/dockerfiles.adoc#packaging.container-images.dockerfiles.cds[Dockerfiles reference documentation].

[[howto.class-data-sharing.training-run-configuration]]
== Preventing Remote Services Interaction During the Training Run

Expand Down
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
[[packaging.container-images.dockerfiles]]
= Dockerfiles

While it is possible to convert a Spring Boot uber jar into a Docker image with just a few lines in the Dockerfile, using the xref:packaging/container-images/efficient-images.adoc#packaging.container-images.efficient-images.layering[layering feature] will result in an optimized image.
While it is possible to convert a Spring Boot uber jar into a Docker image with just a few lines in the `Dockerfile`, using the xref:packaging/container-images/efficient-images.adoc#packaging.container-images.efficient-images.layering[layering feature] will result in an optimized image.
When you create a jar containing the layers index file, the `spring-boot-jarmode-tools` jar will be added as a dependency to your jar.
With this jar on the classpath, you can launch your application in a special mode which allows the bootstrap code to run something entirely different from your application, for example, something that extracts the layers.

Expand All @@ -28,32 +28,12 @@ Available commands:
help Help about any command
----

The `extract` command can be used to easily split the application into layers to be added to the Dockerfile.
Here is an example of a Dockerfile using `jarmode`.
The `extract` command can be used to easily split the application into layers to be added to the `Dockerfile`.
Here is an example of a `Dockerfile` using `jarmode`.

[source,dockerfile]
----
# Perform the extraction in a separate builder container
FROM bellsoft/liberica-openjre-debian:17-cds AS builder
WORKDIR /builder
# This points to the built jar file in the target folder
# Adjust this to 'build/libs/*.jar' if you're using Gradle
ARG JAR_FILE=target/*.jar
# Copy the jar file to the working directory and rename it to application.jar
COPY ${JAR_FILE} application.jar
# Extract the jar file using an efficient layout
RUN java -Djarmode=tools -jar application.jar extract --layers --destination extracted
# This is the runtime container
FROM bellsoft/liberica-openjre-debian:17-cds
WORKDIR /application
# Copy the extracted jar contents from the builder container into the working directory in the runtime container
# Every copy step creates a new docker layer
# This allows docker to only pull the changes it really needs
COPY --from=builder /builder/extracted/dependencies/ ./
COPY --from=builder /builder/extracted/spring-boot-loader/ ./
COPY --from=builder /builder/extracted/snapshot-dependencies/ ./
COPY --from=builder /builder/extracted/application/ ./
include::reference:partial$dockerfile[]
# Start the application jar - this is not the uber jar used by the builder
# This jar only contains application code and references to the extracted jar files
# This layout is efficient to start up and CDS friendly
Expand All @@ -67,10 +47,31 @@ Assuming the above `Dockerfile` is in the current directory, your Docker image c
$ docker build --build-arg JAR_FILE=path/to/myapp.jar .
----

This is a multi-stage Dockerfile.
This is a multi-stage `Dockerfile`.
The builder stage extracts the directories that are needed later.
Each of the `COPY` commands relates to the layers extracted by the jarmode.

Of course, a Dockerfile can be written without using the `jarmode`.
Of course, a `Dockerfile` can be written without using the `jarmode`.
You can use some combination of `unzip` and `mv` to move things to the right layer but `jarmode` simplifies that.
Additionally, the layout created by the `jarmode` is CDS friendly out of the box.



[[packaging.container-images.dockerfiles.cds]]
== CDS

If you want to additionally enable xref:reference:packaging/class-data-sharing.adoc[CDS], you can use this `Dockerfile`:
[source,dockerfile]
----
include::reference:partial$dockerfile[]
# Execute the CDS training run
RUN java -XX:ArchiveClassesAtExit=application.jsa -Dspring.context.exit=onRefresh -jar application.jar
# Start the application jar with CDS enabled - this is not the uber jar used by the builder
# This jar only contains application code and references to the extracted jar files
# This layout is efficient to start up and CDS friendly
ENTRYPOINT ["java", "-XX:SharedArchiveFile=application.jsa", "-jar", "application.jar"]
----

This is mostly the same as the above `Dockerfile`.
As the last steps, it creates the CDS archive by doing a training run and passes the CDS parameter to `java -jar`.

Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
# Perform the extraction in a separate builder container
FROM bellsoft/liberica-openjre-debian:17-cds AS builder
WORKDIR /builder
# This points to the built jar file in the target folder
# Adjust this to 'build/libs/*.jar' if you're using Gradle
ARG JAR_FILE=target/*.jar
# Copy the jar file to the working directory and rename it to application.jar
COPY ${JAR_FILE} application.jar
# Extract the jar file using an efficient layout
RUN java -Djarmode=tools -jar application.jar extract --layers --destination extracted

# This is the runtime container
FROM bellsoft/liberica-openjre-debian:17-cds
WORKDIR /application
# Copy the extracted jar contents from the builder container into the working directory in the runtime container
# Every copy step creates a new docker layer
# This allows docker to only pull the changes it really needs
COPY --from=builder /builder/extracted/dependencies/ ./
COPY --from=builder /builder/extracted/spring-boot-loader/ ./
COPY --from=builder /builder/extracted/snapshot-dependencies/ ./
COPY --from=builder /builder/extracted/application/ ./

0 comments on commit 45cecf5

Please sign in to comment.