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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 - 15: 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 20 - 22: 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 27 - 30: The image OS is updated and additional packages are installed (ps, netstat, bash).
Line 37 - 38: 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 41: 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 [ ! "$js_http_port" = "" ]
then
  js_args="$js_args --http-port=$js_http_port"
fi

if [ ! "$js_https_port" = "" ]
then
  js_args="$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 48: 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 49 - 51: The tarball is extracted. For Unix Agents no installer is used.
Line 52 - 53: The jobscheduler user account is made the owner of installed files and the start script is made executable.
Line 54: 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 59: 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 67: The HTTP port and optionally the HTTPS port are exposed to the Docker host. Both ports can be forwarded by environment variables when running the container, overwriting the build-time values. This is relevant only if users want to use ports inside the container that are different from the default values. In most situations the default ports should be fine and are mapped to outside ports on the Docker host when starting the container.
Line 69: The start script is executed and is dynamically parameterized from environment variables that are forwarded when starting the container.

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