Environment variable not picking up in dockerfile - docker

Question

I have a Vue application which I serve with docker, currently I want to use environment variables to target specific project repo. But when I am setting env variables, it's not picking up in dockerfile,
What am I doing wrong in my setup ?
NPM scripts.
scripts: {
"build:project1": "vue-cli-service build src/project1/main.js",
"deploy:project1": "cross-env PROJECT_REPO=project1 bash build_deploy.sh"
}
build_deploy.sh
#!/bin/bash
docker build -t ${PROJECT_REPO} .
Dockerfile
# build stage
FROM node:lts-alpine as build-stage
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build:${PROJECT_REPO}
# production stage
FROM nginx:stable-alpine as production-stage
COPY --from=build-stage /app/dist /usr/share/nginx/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

Answer 1

Aha. Found it. I was missing ARG in docker file
# build stage
ARG PROJECT_REPO
FROM node:lts-alpine as build-stage
ARG PROJECT_REPO
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build:${PROJECT_REPO}
# production stage
FROM nginx:stable-alpine as production-stage
COPY --from=build-stage /app/dist /usr/share/nginx/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]
Reference taken from docs: https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact