Table of Contents

Introduction

This article explains a simplified build process for Agent images that is extracted from the SOS build environment.
Users can build their own Docker images for Agents.This article explains options how to create the Agent image.

Build Environment

For the build environment the following directory hierarchy is assumed:

...

Code Block

language	bash
title	Dockerfile for Agent Image
linenumbers	true
collapse	true

FROM openjdk:8-jre-alpine

LABEL maintainer="Software- und Organisations-Service GmbH"# BUILD PRE-IMAGE

FROM alpine:latest AS js7-pre-image

# BUILD SETTINGS

# provide provide build arguments for release information
ARG JS_RELEASE
ARG JS_RELEASE_MAJOR

# default user id has to match later run-time user
ARG JS_USER_ID=${UID:-1001}
ARG JS_HTTP_INTERFACEPORT=${JS_HTTP_INTERFACEPORT:-""4445}

ARG JS_HTTP_PORT=# add/copy tarball
ADD https://download.sos-berlin.com/JobScheduler.${JS_HTTP_PORT:-4445}
ARG JS_HTTPS_INTERFACE=RELEASE_MAJOR}/js7_agent_unix.${JS_HTTPS_INTERFACE:-""}
ARG JS_HTTPS_PORT=RELEASE}.tar.gz /usr/local/src/
# COPY js7_agent_unix.${JS_HTTPS_PORT:-""}
ARG JS_JAVA_OPTIONS=${JS_JAVA_OPTIONS}

# RUN-TIME SETTINGS

# JS7 JobScheduler ports and Java options
ENV RUN_JS_HTTP_INTERFACE=${RUN_JS_HTTP_INTERFACE:-$JS_HTTP_INTERFACE}
ENV RUN_JS_HTTP_PORT=${RUN_JS_HTTP_PORT:-$JS_HTTP_PORT}
ENV RUN_JS_HTTPS_INTERFACE=${RUN_JS_HTTPS_INTERFACE:-$JS_HTTPS_INTERFACE}
ENV RUN_JS_HTTPS_PORT=${RUN_JS_HTTPS_PORT}
ENV RUN_JS_JAVA_OPTIONS=${RUN_JS_JAVA_OPTIONS:-$JS_JAVA_OPTIONS}

# PREPARATION

# install process tools, net tools, bash
RUN apk update && apk add --no-cache \
    procps \
    net-tools \
    bash

# setup working directory
RUN mkdir -p /var/sos-berlin.com/js7
WORKDIR /var/sos-berlin.com/js7

# add/copy installation tarball
ADD https://download.sos-berlin.com/JobScheduler.${JS_RELEASE_MAJOR}/js7_agent_unix.${JS_RELEASE}.tar.gz /usr/local/src/
# COPY js7_agent_unix.${JS_RELEASE}.tar.gz /usr/local/src/

# add start script
COPY start-agent.sh /usr/local/bin/

# INSTALLATION

# extract tarball
# for JDK < 12, /dev/random does not provide sufficient entropy, see https://kb.sos-berlin.com/x/lIM3
# add jobscheduler user account and make it the owner of directories
RUN adduser -u ${JS_USER_ID:-1001} --disabled-password --home /home/jobscheduler --no-create-home --shell /bin/bash jobscheduler jobscheduler && \
    test -e /usr/local/src/js7_agent_unix.${JS_RELEASE}.tar.gz && \
    tar xfvz /usr/local/src/js7_agent_unix.${JS_RELEASE}.tar.gz -C RELEASE}.tar.gz /usr/local/src/

RUN mkdir -p /var/sos-berlin.com/js7 && \
    test -e /usr/local/src/js7_agent_unix.${JS_RELEASE}.tar.gz && \
    tar xfvz /usr/local/src/js7_agent_unix.${JS_RELEASE}.tar.gz -C /var/sos-berlin.com/js7

# add start script
COPY start-agent.sh /var/sos-berlin.com/js7/

# copy default configuration
COPY config/ /var/sos-berlin.com/js7/agent/var_$JS_HTTP_PORT/config/

# BUILD IMAGE

FROM alpine:latest AS js7-image

LABEL maintainer="Software- und Organisations-Service GmbH"

# provide build arguments for release information
ARG JS_RELEASE
ARG JS_RELEASE_MAJOR

# default user id has to match later run-time user
ARG JS_USER_ID=${UID:-1001}
ARG JS_HTTP_INTERFACE=${JS_HTTP_INTERFACE:-""}
ARG JS_HTTP_PORT=${JS_HTTP_PORT:-4445}
ARG JS_HTTPS_INTERFACE=${JS_HTTPS_INTERFACE:-""}
ARG JS_HTTPS_PORT=${JS_HTTPS_PORT:-""}
ARG JS_JAVA_OPTIONS=${JS_JAVA_OPTIONS}

# JS7 JobScheduler ports and Java options
ENV RUN_JS_HTTP_INTERFACE=${RUN_JS_HTTP_INTERFACE:-$JS_HTTP_INTERFACE}
ENV RUN_JS_HTTP_PORT=${RUN_JS_HTTP_PORT:-$JS_HTTP_PORT}
ENV RUN_JS_HTTPS_INTERFACE=${RUN_JS_HTTPS_INTERFACE:-$JS_HTTPS_INTERFACE}
ENV RUN_JS_HTTPS_PORT=${RUN_JS_HTTPS_PORT}
ENV RUN_JS_JAVA_OPTIONS=${RUN_JS_JAVA_OPTIONS:-$JS_JAVA_OPTIONS}

COPY --from=js7-pre-image ["/var/sos-berlin.com/js7",  && \
    rm /usr/local/src/js7_agent_unix.${JS_RELEASE}.tar.gz && \
    chown -R jobscheduler:jobscheduler /var/sos-berlin.com && \
    chmod +x /usr/local/bin/start-agent.sh && "/var/sos-berlin.com/js7"]

# INSTALLATION

# install process tools, net tools, bash, openjdk
# for JDK < 12, /dev/random does not provide sufficient entropy, see https://kb.sos-berlin.com/x/lIM3
# make default user the owner of directories
RUN apk update && apk add --no-cache \
    sed -i 's/securerandom.source=file:\/dev\/random/securerandom.source=file:\/dev\/urandom/g' /usr/lib/jvm/java-1.8-openjdk/jre/lib/security/java.security

# CONFIGURATION

# copy default configuration
# COPY --chown=jobscheduler:jobscheduler config/ /var/sos-berlin.com/js7/agent/var_$JS_HTTP_PORT/config/

# CODA

# run-time user, can be overwritten when running the container
USER jobscheduler

CMD ["sh","-c","/usr/local/bin/start-agent.sh --http-port=$RUN_JS_HTTP_INTERFACE:$RUN_JS_HTTP_PORT --https-port=$RUN_JS_HTTPS_INTERFACE:$RUN_JS_HTTPS_PORT --java-options=\"$RUN_JS_JAVA_OPTIONS\""]

Explanation:

--repository=http://dl-cdn.alpinelinux.org/alpine/edge/community \
    procps \
    net-tools \
    bash \
    openjdk8 && \
    adduser -u ${JS_USER_ID:-1001} --disabled-password --home /home/jobscheduler --no-create-home --shell /bin/bash jobscheduler jobscheduler && \
    chown -R jobscheduler:jobscheduler /var/sos-berlin.com && \
    mv /var/sos-berlin.com/js7/start-agent.sh /usr/local/bin/ && \
    chmod +x /usr/local/bin/start-agent.sh && \
    sed -i 's/securerandom.source=file:\/dev\/random/securerandom.source=file:\/dev\/urandom/g' /usr/lib/jvm/java-1.8-openjdk/jre/lib/security/java.security

# CODA

# run-time user, can be overwritten when running the container
USER jobscheduler

CMD ["sh","-c","/usr/local/bin/start-agent.sh --http-port=$RUN_JS_HTTP_INTERFACE:$RUN_JS_HTTP_PORT --https-port=$RUN_JS_HTTPS_INTERFACE:$RUN_JS_HTTPS_PORT --java-options=\"$RUN_JS_JAVA_OPTIONS\""]

Explanation:

The build script implements two stages to exclude installer files from the resulting image.
Line 3: The base image is the current Alpine image at build-time.
Line 6 - 8: The release identification is injected by build arguments. This information is used to determine the tarball to be downloaded or copied.
Line 11 - 12:
Line 1: The base image is OpenJDK Java 1.8 (Alpine based). You can run Agents with newer Java releases, however, stick to Oracle, OpenJDK or AdoptOpenJDK as the source for your Java base image. Alternatively you can use your own base image and install Java 1.8 or later on top of this.
Line 8 - 9: The release identification is injected by build arguments. This information is used to determine the tarball to be downloaded or copied.
Line 12 - 17: Defaults for the user id running the Agent inside the container as well as HTTP and HTTPS ports are provided. These values can be overwritten by providing the respective build arguments.
Line 22 - 26: Environment variables are provided at run-time, not at build-time. They can be used to specify ports and Java options when running the container.
Line 31 - 34: The image OS is updated and additional packages are installed (ps, netstat, bash).
Line 41 - 42: You can either download the Agent tarball directly from the SOS web site or you store the tarball with the build directory and copy from this location.
Line 14 - 16: The tarball is extracted. For Unix Agents no installer is used.

Line 19: The start- 45: The start-agent.sh script is copied from the build directory to the image. Users can apply their own version of the start script. The start script used by SOS looks like this:

Code Block

language	bash
title	Agent Start Script
linenumbers	true
collapse	true

#!/bin/sh

js_http_port=""
js_https_port=""
js_java_options=""

for option in "$@"
do
  case "$option" in
         --http-port=*)    js_http_port=`echo "$option" | sed 's/--http-port=//'`
                           ;;
         --https-port=*)   js_https_port=`echo "$option" | sed 's/--https-port=//'`
                           ;;
         --java-options=*) js_java_options=`echo "$option" | sed 's/--java-options=//'`
                           ;;
         *)                echo "unknown argument: $option"
                           exit 1
                           ;;
  esac
done


js_args=""

if [ ! "$js_http_port" = "" ] && [ ! "$js_http_port" = ":" ]
then
  js_args="$js_args --http-port=$js_http_port"
fi

if [ ! "$js_https_port" = "" ] && [ ! "$js_https_port" = ":" ]
then
  js_args="$js_args --https-port=$js_https_port"
fi

if [ ! "$js_java_options" = "" ]
then
  js_args="$js_args --java-options=$js_java_options"
fi

echo "starting Agent: /var/sos-berlin.com/js7/agent/bin/agent.sh start $js_args"
/var/sos-berlin.com/js7/agent/bin/agent.sh start $js_args && tail -f /dev/null

Line 22: Optionally a config folder is available in the build directory and is copied to the config sub-folder in the image. The parent folder var_<port> is determined from the HTTP port that the Agent is built for. This can be useful to create an image with individual default settings in configuration files, see JS7 - Agent Configuration Items.
Line 35 - 40: Defaults for the user id running the Agent inside the container as well as HTTP and HTTPS ports are provided. These values can be overwritten by providing the respective build arguments.
Line 43 - 47: Environment variables are provided at run-time, not at build-time. They can be used to specify ports and Java options when running the container.
Line 56 - 60: The image OS is updated and additional packages are installed (ps, netstat, bash).
Line 61: The most recent Java 1.8 package available with Alpine is applied. Agents can be operated with newer Java releases, however, stick to Oracle, OpenJDK or AdoptOpenJDK as the source for your Java LTS release. Alternatively you can use your own base image and install Java 1.8 or later on top of this.
Line 62Line 52: The jobscheduler user account is created and is assigned the user id and group id handed over by the respective build arguments. This translates to the fact that the account running the Agent inside the container and the account that starts the container are assigned the same user id and group id. This allows the account running the container to access any files created by the Agent in mounted volumes with identical permissions.
Line 53 63 - 5565: The tarball is extracted. For Unix Agents no installer is used.Line 56 - 57: The jobscheduler user account is made the owner of installed files and the start script is made executable.
Line 5866: Java releases < Java 12 make use of /dev/random for random number generation. This is a bottleneck as random number generation with this file is blocking. Instead /dev/urandom should be used that implements non-blocking behavior. The change of the random file is applied to the Java security file.
Line 63: Optionally a config folder is available in the build directory and is copied to the config sub-folder in the image. The parent folder var_<port> is determined from the HTTP port that the Agent is built for. This can be useful to create an image with individual default settings in configuration files, see JS7 - Agent Configuration Items.
be used that implements non-blocking behavior. The change of the random file is applied to the Java security file.
Line 73Line 70: The start script is executed and is dynamically parameterized from environment variables that are forwarded when starting the container.

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