How to make environment variables available at container build-time & runtime in docker?-CodePudding

I am working on a nextjs docker project trying to pass my environment variables to be accessed at container build time and run time. I basically referred to Nextjs's template Dockerfile and passed my required env vars both as build args and environment in my docker-compose.yml as such

version: "3.7"
services:
  app:
    container_name: frontend
    build: 
      context: .
      args:
        - API_URL=http://path-to-my-external-api-url
        - NEXT_PUBLIC_CLIENT_API_URL=http://path-to-my-external-api-url
    environment:
      - NODE_ENV=production
      - API_URL=http://path-to-my-external-api-url
      - NEXT_PUBLIC_CLIENT_API_URL=http://path-to-my-external-api-url
    ports:
      - "3000:3000"
  nginx:
    depends_on: 
      - app
    container_name: frontend-nginx
    build: ./nginx
    ports:
      - "8080:8080"

Then I access these env vars in my Dockerfile like

...
FROM node:14-alpine AS builder
WORKDIR /app
COPY ./app .
COPY --from=deps /app/node_modules ./node_modules
ARG API_URL
ARG NEXT_PUBLIC_CLIENT_API_URL
ENV API_URL=${API_URL}
ENV NEXT_PUBLIC_CLIENT_API_URL=${NEXT_PUBLIC_CLIENT_API_URL}
RUN npm run build
...

Then the app is built in gitlab pipeline which fails at the build stage defined below

...
Build and Push App:
  image: docker:19.03.5
  services:
    - docker:19.03.5-dind
  stage: Build and Push
  script:
    - apk add python3
    - pip3 install awscli
    - docker build --compress -t $ECR_REPO:$CI_COMMIT_SHORT_SHA .
    - $(aws ecr get-login --no-include-email --region ap-south-1)
    - docker push $ECR_REPO:$CI_COMMIT_SHORT_SHA
    - docker tag $ECR_REPO:$CI_COMMIT_SHORT_SHA $ECR_REPO:latest
    - docker push $ECR_REPO:latest
  rules:
    - if: '$CI_COMMIT_BRANCH =~ /^(main|production)$/'
...

I was able to build and run my container locally. But it fails during the above gitlab ci pipeline stage with Error: connect ECONNREFUSED 127.0.0.1:80 at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1159:16) which I assume is related to inability to load these environment variables.

How do I fix this? Is is needed to even pass the variables as args and environment twice in the docker-compose file (I did this because I found that only when passing them both as args and environment works in building my container locally).

This is my first time working with ci/cd and docker and any corrections to my code or suggestions to optimize it is much appreciated. Thanks for you time.

EDIT: Fix hyperlink error

CodePudding user response：

In the Dockerfile you posted the args are declared, however, you do not load them at build time on the docker build command with the --build-arg flag, on a command similar to this:

 docker build --compress -t $ECR_REPO:$CI_COMMIT_SHORT_SHA --build-arg API_URL=<url> NEXT_PUBLIC_CLIENT_API_URL=<url> .

Reference: https://docs.docker.com/engine/reference/commandline/build/#options