In docker compose file set environment as list - scala

Question

I have an application that on play that use aerospike
in application.conf i have a param that i can rewrite from environments
aerospike.hosts = ["192.168.33.10"]
aerospike.hosts = ${?DS_AEROSPIKE_HOSTS}
how i can set list of hosts in my docker compose file?
version: '3.1'
services:
ds-aerospike-db:
image: aerospike/aerospike-server
restart: always
volumes:
- volume:/opt/aerospike/etc
command: ["--config-file","/opt/aerospike/etc/aerospike.conf"]
ports:
- 3000:3000
dashboard:
image: dashboard:0.1
restart: always
ports:
- 9000:9000
environment:
DS_AEROSPIKE_HOSTS: '["192.168.33.10"]'
this format is an error DS_AEROSPIKE_HOSTS: '["192.168.33.10"]'

Answer 1

I believe you can't pass an array to the ENV variable.
But you can pass it as a string, and then, later, parse string at your application.
environment:
- DS_AEROSPIKE_HOSTS='192.168.33.10,192.168.33.11'
the valid docker-compose.yml syntax is stated at docs
https://docs.docker.com/compose/environment-variables/
I'm not familiar with scala, but I believe you can do something like
aerospike.hosts = ${?DS_AEROSPIKE_HOSTS}.split(',')

Answer 2

You have a couple of options:
You can include a docker.conf file in your Docker build and inject the settings you want into that file. Then you can include the docker.conf file from your application.conf. E.g. add this to your application.conf:
include "docker.conf"
You can use an environment varible to pass a string value (as suggested by Stanislav) but then convert it to a sequence. The idiomatic way to do this is to make a ConfigLoader and then use it to convert a String to a Seq[String]. E.g. something like:
implicit val stringSeqLoader: ConfigLoader[Seq[String]] =
ConfigLoader(_.getString).map(_.split(','))