Alauda Service Mesh

Java Application Containerization Specification

Note: Applicable to ACP v3.14.3, v3.16.2, v3.18 and above.

Only when a Java application uses the JAVA_TOOL_OPTIONS environment variable, the following containerization specifications must be followed to ensure that the application's own configuration of the JAVA_TOOL_OPTIONS environment variable takes effect. Specifically, when deploying in a Container Platform, the application's Deployment should explicitly declare the JAVA_TOOL_OPTIONS environment variable. An example is as follows:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: your-java-app
spec:
  template:
    spec:
      containers:
        - env: # Configuration examples
            - name: JAVA_TOOL_OPTIONS
              value: "-Xmx1024m -Xms512m"
          name: your-java-app

Reason: When a Java application (Deployment) is added to the platform as a service (OpenTelemetry governance), the Java Agent is automatically injected by appending the -javaagent parameter to the pod JAVA_TOOL_OPTIONS environment variable, e.g. -javaagent:/otel-auto-instrumentation-java/javaagent.jar. This may be overridden if JAVA_TOOL_OPTIONS is configured in any other way.

Java Application Containerization Specification (Old)

Note: Applicable to ACP versions other than the new specifications above.

To ensure the platform's governance capabilities can be effectively applied to your Java applications, please follow the following Java application containerization specification during the development and building process:

Base Image Selection

It is recommended to use versions of JDK 8u212 or later as the base image.

Dockerfile Template

Please refer to the Dockerfile template and instructions provided in this document and modify the Dockerfile file used in your Java application project accordingly.

The Dockerfile template is as follows:

FROM eclipse-temurin:8-alpine

VOLUME /tmp

# Set the container's timezone and add the admin account, also create its home directory.
# Note: The instruction to set the timezone may vary depending on the OS of the base image.
# Note: This step requires accessing the internet to download dependencies. If you are in an isolated internal network, consider using a public base image to complete this step.
RUN apk update \
    && apk add --no-cache tzdata \
    && cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime \
    && echo "Asia/Shanghai" > /etc/timezone \
    && adduser -D admin

# The WORKDIR instruction makes it easier to use relative paths in subsequent instructions to simplify the script.
WORKDIR /home/admin/

# For security reasons, use a non-root account to avoid running commands like apt-get.
USER admin

# The COPY --chown option eliminates the need to run chown again.
# Note: Ensure that start.sh has executable permissions.
COPY --chown=admin:admin start.sh \
     target/app.jar \
     /home/admin/

# Start the container by executing the script.
ENTRYPOINT ["./start.sh"]

The content of the start.sh script referenced in the Dockerfile template is as follows. Please save the script file in the same directory as the Dockerfile.

#!/bin/sh

# -e Exit immediately if a command exits with a non-zero status.
# -x Display commands and their arguments as they are executed.
set -ex

# Use the value of the JAVA_OPTS environment variable as the startup parameter for the JAVA service, automatically replacing it with the value of the JAVA_OPTS environment variable in the current environment at runtime.
# Use exec so that the Java program can receive the SIGTERM signal.
exec /usr/bin/java ${JAVA_OPTS} \
     -Djava.security.egd=file:/dev/./urandom \
     -jar /home/admin/app.jar ${RUN_ARGS} "$@"
ON THIS PAGE