Containers & K8S

# Distroless Java Images # https://console.cloud.google.com/gcr/images/distroless/GLOBAL # https://github.com/GoogleContainerTools/distroless#what-images-are-available $ docker pull gcr.io/distroless/java-base-debian12:latest $ docker pull gcr.io/distroless/java21-debian12:latest # Distroless Static & Base $ docker pull gcr.io/distroless/static-debian12:latest $ docker pull gcr.io/distroless/base-debian12:latest # GraalVM native-image base $ docker pull cgr.dev/chainguard/graalvm-native:latest $ docker pull cgr.dev/chainguard/static:latest-glibc $ docker pull cgr.dev/chainguard/jdk:latest # Openjdk # https://github.com/docker-library/openjdk $ docker pull openjdk:25-slim # Eclipse Temurin # https://github.com/adoptium/containers#supported-images $ docker pull eclipse-temurin:24-jdk $ docker pull eclipse-temurin:24-alpine # Oracle OpenJDK $ docker pull container-registry.oracle.com/java/openjdk:latest # Oracle Java (NFTC) # https://github.com/oracle/docker-images/tree/main/OracleJava $ docker pull container-registry.oracle.com/java/jdk:latest # Azul Zulu # https://github.com/zulu-openjdk/zulu-openjdk $ docker pull azul/zulu-openjdk-debian:24-jre $ docker pull azul/zulu-openjdk-alpine:24-jre $ docker pull azul/prime-debian:latest # Amazon Corretto # https://github.com/corretto/corretto-docker $ docker pull amazoncorretto:23 $ docker pull amazoncorretto:23-alpine # Microsoft OpenJDK # https://learn.microsoft.com/en-us/java/openjdk/containers $ docker pull mcr.microsoft.com/openjdk/jdk:21-ubuntu $ docker pull mcr.microsoft.com/openjdk/jdk:21-distroless # Liberica # https://github.com/bell-sw/Liberica/tree/master/docker/repos/liberica-openjre-debian $ docker pull bellsoft/liberica-openjdk-debian:latest $ docker pull bellsoft/liberica-openjdk-alpine-musl:latest $ docker pull bellsoft/liberica-openjdk-alpine:latest (libc) # GraalVM CE & EE # https://github.com/graalvm/container $ docker pull ghcr.io/graalvm/graalvm-community:latest $ docker pull ghcr.io/graalvm/native-image-community:muslib $ docker pull container-registry.oracle.com/graalvm/native-image:latest # GraalVM CE Dev Builds (No docker images available) https://github.com/graalvm/graalvm-ce-dev-builds/releases/ # Jetbrains Runtime (No docker images available) https://github.com/JetBrains/JetBrainsRuntime/releases # Azul Zulu OpenJDK & Mission Control (Homebrew on MacOS) # https://github.com/mdogan/homebrew-zulu $ brew tap mdogan/zulu $ brew install <name>

# On M1 mac $ docker run \ --platform linux/amd64 \ --pull always \ -it \ --rm \ -p 8080:80 \ --name openjdk-playground \ ghcr.io/sureshg/containers:openjdk-latest # Default busybox image should work. $ brew install cdebug $ cdebug exec \ --privileged \ -it \ --rm \ --platform linux/amd64 \ docker://openjdk-playground # Extract a file from the Docker environment and store it locally $ docker run \ --rm \ --entrypoint cat \ busybox:latest \ '/bin/ls' > ls # OR copy files from a container $ docker cp <CONTAINER>:/app/app/jar . # OR $ id=$(docker create ghcr.io/sureshg/containers:openjdk-latest) $ docker cp $id:/app/app.jar - > app.tar $ docker rm -v $id

$ cat << EOF >App.java import static java.lang.System.out; public class App { void main() { var version = "• Java %s running on %s %s".formatted( System.getProperty("java.version"), System.getProperty("os.name"), System.getProperty("os.arch")); out.println(version); long unit = 1024 * 1024L; long heapSize = Runtime.getRuntime().totalMemory(); long heapFreeSize = Runtime.getRuntime().freeMemory(); long heapUsedSize = heapSize-heapFreeSize; long heapMaxSize = Runtime.getRuntime().maxMemory(); out.println("• [CPU] Active Processors: " + Runtime.getRuntime().availableProcessors()); out.println("• [Mem] Current Heap Size (Committed) : " + heapSize/unit + " MiB"); out.println("• [Mem] Current Free memeory in Heap : " + heapFreeSize/unit + " MiB"); out.println("• [Mem] Currently used memory : " + heapUsedSize/unit + " MiB"); out.println("• [Mem] Max Heap Size (-Xmx) : " + heapMaxSize/unit + " MiB"); } } EOF $ docker run \ -it \ --rm \ --cpus=2 \ --memory=512m \ --pull always \ --mount type=bind,source=$(pwd),destination=/app,readonly \ --mount type=bind,source=/,destination=/host,readonly \ --name openjdk \ openjdk:25-slim \ java \ --source 25 --enable-preview \ -XX:+UnlockExperimentalVMOptions \ -XX:+UnlockDiagnosticVMOptions \ -XX:+PrintFlagsFinal \ -XX:MaxRAMPercentage=0.8 \ -XX:-MaxFDLimit \ -Xlog:gc \ /app/App.java \ | grep -e "Use.*GC" -e "Active" -e "Using" -e "Max.*Limit" -e "Container" -e "•"

# OpenJDK reverts to Serial GC when it detects < 2 CPUs or < 2GB RAM $ docker run -it --rm --cpus=1 --memory=1G openjdk:25-slim java -Xlog:gc --version #[0.007s][info][gc] Using Serial

$ docker run \ -it --rm \ --cpus="0.5" \ --memory="512m" \ --memory-swap="640m" \ --pids-limit 512 \ --cap-drop=ALL \ --cap-add=DAC_OVERRIDE \ --security-opt=no-new-privileges \ --ulimit nproc=20:20 \ --ulimit fsize=1000000 \ --user nobody \ --network none \ --read-only \ --tmpfs /tmp \ --name sandboxed \ --workdir /app \ --mount type=bind,source=$PWD,destination=/app,readonly \ --mount type=bind,source=/var/run/docker.sock,destination=/var/run/docker.sock,readonly \ --mount type=bind,source=/usr/bin/docker,destination=/usr/bin/docker,readonly \ --mount type=bind,source=/proc/,target=/host/proc/,ro=true \ --mount type=bind,source=/sys/fs/cgroup/,target=/host/sys/fs/cgroup,ro=true \ openjdk:25-slim java --enable-preview src/App.java # --security-opt seccomp=my_sandbox # --cap-add=chown \ # --cap-add=setgid \ # --cap-add=setuid \ # --cap-add=sys_chroot \ # --cap-add=audit_write \ # --cap-add=kill \ # --cap-add=sys_tty_config \ # --cap-add=DAC_OVERRIDE - Needed to allow overwriting the file # Create nobody user # RUN useradd --shell /bin/sh --create-home --uid 65534 nobody

# Check if running on docker container $ docker run \ -it \ --rm \ --pull always \ openjdk:25-slim \ sh -c "cat /proc/self/cgroup | grep -i '/docker'" # Check if running on Kubernets $ docker run \ -it \ --rm \ --pull always \ openjdk:25-slim \ sh -c "printenv | grep SERVICE"

$ docker run -it --rm --memory=256m --cpus=1 --mount type=bind,source=/,destination=/host --name alpine alpine /# chroot /host # docker version

FROM alpine ENTRYPOINT while :; do nc -k -l -p $PORT -e sh -c 'echo -e "HTTP/1.1 200 OK\n\n hello, world"'; done # https://github.com/jamesward/hello-netcat # docker build -t hello-netcat . # docker run -p 8080:80 -e PORT=80 -it hello-netcat

# forward request and error logs to docker log collector RUN ln -sf /dev/stdout /var/log/nginx/access.log \ && ln -sf /dev/stderr /var/log/nginx/error.log # OR output directly to /proc/self/fd/1 (STDOUT) /proc/self/fd/2 (STDERR) # https://docs.docker.com/config/containers/logging/configure/

#!/bin/bash ## Entrypoint script for my-app. This script is to show how to write ## an entrypoint script that actually passes down signals from Docker. ## Load our DB Password into a runtime only Environment Variable if [ -f /run/secrets/password ] then echo "Loading DB password from secrets file" DB_PASS=$(cat /run/secrets/password) export DB_PASS fi ## Run the Application exec my-app

ENTRYPOINT ["../../myapp-entrypoint.sh"]

FROM debian:stable-slim ENV HTTP_PROXY="http://proxy.test.com:8080" ENV HTTPS_PROXY="http://proxy.test.com:8080" ENV NO_PROXY="*.test1.com,*.test2.com,127.0.0.1,localhost"