Docker args in Docker compose does not pass into Dockerfile - docker

Question

I am using the latest Docker Toolbox under Windows 10 to build the native image for Quarkus applciations.
$ docker -v
Docker version 19.03.1, build 74b1e89e8a
The docker-compose.yaml file:
version: '3.7' # specify docker-compose version
services:
blogdb:
image: postgres
ports:
- "5432:5432"
restart: always
environment:
POSTGRES_PASSWORD: password
POSTGRES_DB: blogdb
POSTGRES_USER: user
volumes:
- ./data:/var/lib/postgresql
post-service:
image: hantsy/quarkus-post-service
build:
context: ./backend
dockerfile: src/main/docker/Dockerfile.multistage
args:
- QUARKUS_DATASOURCE_URL
environment:
QUARKUS_DATASOURCE_URL: jdbc:postgresql://blogdb:5432/blogdb
ports:
- "8080:8080" #specify ports forewarding
depends_on:
- blogdb
And the Dockerfile:
## Stage 1 : build with maven builder image with native capabilities
FROM quay.io/quarkus/centos-quarkus-maven:19.1.1 AS build
ARG QUARKUS_DATASOURCE_URL
RUN echo "QUARKUS_DATASOURCE_URL>>>: $QUARKUS_DATASOURCE_URL"
ENV QUARKUS_DATASOURCE_URL $QUARKUS_DATASOURCE_URL
WORKDIR /usr/src/app
COPY pom.xml .
RUN mvn -U dependency:go-offline dependency:resolve-plugins -Pnative
COPY src/ /usr/src/app/src/
USER root
RUN chown -R quarkus /usr/src/app
USER quarkus
RUN mvn clean package -Pnative -Dquarkus.datasource.url=$QUARKUS_DATASOURCE_URL
## -DskipTests -Dmaven.test.skip=true
## Stage 2 : create the docker final image
FROM registry.access.redhat.com/ubi8/ubi-minimal
WORKDIR /work/
COPY --from=build /usr/src/app/target/*-runner /work/application
RUN chmod 775 /work
EXPOSE 8080
CMD ["./application", "-Dquarkus.http.host=0.0.0.0"]
The echo always prints blank for the arg: QUARKUS_DATASOURCE_URL.
I have tried to change the args to QUARKUS_DATASOURCE_URL=${QUARKUS_DATASOURCE_URL}, it still prints blank.
It can not read the environment defined in docker-compose.yaml file as Docker docs described said.
If set value as a string directly, it workw, eg. QUARKUS_DATASOURCE_URL="test".

Answer 1

According to this, you need to follow window PowerShell syntax.
It seems that you must use $env:arg or %arg% when using PowerShell or cmd, but you must use $arg when using docker commands.
FROM microsoft/nanoserver
ARG QUARKUS_DATASOURCE_URL=some_default_value
RUN echo %QUARKUS_DATASOURCE_URL%
ENV QUARKUS_DATASOURCE_URL %QUARKUS_DATASOURCE_URL%
Can't get Docker to expand ARG define at head of file
It seems that you must use $env:arg or %arg% when using powershell or
cmd, but you must use $arg when using docker commands.