Dockerfile pass environments on docker compose build

I have written a Dockerfile which uses two arguments:

FROM jessie
MAINTAINER Zeinab Abbasimazar
#Build Arguments
ARG REP_USER
ARG REP_PASS
# Build
RUN echo 'REP_USER:'$REP_USER', REP_PASS:'$REP_PASS

I wrote a docker-compose.yml for build:

version: "2"
services:
  ui:
    build:
      context: .
      dockerfile: Dockerfile
      args:
        REP_USER: $REP_USER
        REP_PASS: $REP_PASS

I don't want to define these arguments directly in the compose file, so I tried to send them during docker compose build:

REP_USER=myusername REP_PASS=mypassword docker-compose build

Which didn't work. I changed my Dockerfile to use these arguments as environment variables; so I removed ARG lines:

FROM jessie
MAINTAINER Zeinab Abbasimazar
# Build
RUN echo 'REP_USER:'$REP_USER', REP_PASS:'$REP_PASS

And docker-compose.yml:

version: "2"
  services:
    ui:
      build:
        context: .
        dockerfile: Dockerfile

And ran REP_USER=myusername REP_PASS=mypassword docker-compose build; still no result.

I also tried to save these information into an env file:

version: "2"
services:
  ui:
    build:
      context: .
      dockerfile: Dockerfile
    env_file:
      - myenv.env

But it seems env files doesn't affect at build time; they are just take part into run time.

EDIT 1:

Docker version is 1.12.6 which doesn't support passing arguments with --build-arg.

EDIT 2:

I tried using .env file as described here:

cat .env 
REP_USER=myusername
REP_PASS=mypassword

I then called docker-compose config which returned:

networks: {}
services:
  ui:
    build:
      args:
        REP_PASS: mypassword
        REP_USER: myusername
      context: /home/zeinab/Workspace/ZiZi-Docker/Test/test-exec-1
      dockerfile: Dockerfile
version: '2.0'
volumes: {}

Which means this resolved my issue.

EDIT 3:

I also tried third section of docker-compose arg documentation in my docker-compose.yml file:

version: "2"
services:
  ui:
    build:
      context: .
      dockerfile: Dockerfile
      args:
        - REP_USER
        - REP_PASS

And executed:

export REP_USER=myusername;export REP_PASS=mypassword;sudo docker-compose build --no-cache

Still not getting what I wanted.

I finally found the solution. I mentioned it in the question too. I first tried it with fail, then I found out that I had a typo naming .env file; it was .evn.

I tried using .env file as described at https://web.archive.org/web/20170705114846/https://docs.docker.com/compose/environment-variables/#the-env-file :

cat .env 
REP_USER=myusername
REP_PASS=mypassword

I then called docker-compose config which returned:

networks: {}
services:
  ui:
    build:
      args:
        REP_PASS: mypassword
        REP_USER: myusername
      context: /home/zeinab/Workspace/ZiZi-Docker/Test/test-exec-1
      dockerfile: Dockerfile
version: '2.0'
volumes: {}

Which means this resolved my issue. I should mention that this answer was really helpful.