Accessing host ip as environment var for production.conf at systemd unite of playframework debian

[mahadi-hossain]

I have a playframework application what I run as debian file generated by sbt-native-packager. In the production.conf file I need to access HOST_IP as environment variable.

But at systemd (when I run sudo systemctl start app.service) app can't access export HOST_IP=$(hostname -I | awk '{print $1}') env variable. I know systemd unit service file can not access environment variable in bashrc or in profile . I know about EnvironmentFile, but that does not support script. I need to create ec2 Amazon Machine Image snap shot that will be used in aws autoscaling. So assigning ip dynamically is necessary.

Is there any way (in build.sbt or other) that I can pass environment variable to my debian app production.conf which is run by systemctl ?

[mkurz]

First, I in production, there is no build.sbt anymore. You are using sbt-native-packer, so the question is which kind of package do you generate? It's very likely Play will get started through a bash script, probably this one here: https://github.com/sbt/sbt-native-packager/blob/d2fd665a5b3dcd2e4f4b15964a98268bfe4b8235/src/main/resources/com/typesafe/sbt/packager/archetypes/scripts/bash-template#L321-L325
As you can see from the lines I referenced you can pass system variables via -Dkey=val arguments, or also use set JAVA_OPTS.
Maybe also have a look in the sbt-native-packer file , I think there might be options you can set to set up the service file so it passes on the variables to your app.

[mahadi-hossain]

Thanks a lot for your kind assistance. Yes I followed that
at build.sbt. This is added at start-script for production .

at build.sbt

bashScriptExtraDefines +=
  """
    |host_ip=$(hostname -I | awk '{print $1}')
    |addJava "-DHOST_IP=$host_ip"
    |""".stripMargin

[mkurz]

So it work? Great 👍

[mahadi-hossain]

It works :)