Passing NODE_ENV to docker to run package.json scripts

Here is two possible implementation.

FYI: you don't need to mention NODE_ENV in package.json if you already set NODE_ENV at the system level or set NODE_ENV during build time or runtime in docker.

Here Dockerfile as same but I used to alpine base image

FROM node:alpineRUN mkdir -p /usr/src/appWORKDIR /usr/src/appCOPY package.json /usr/src/app/RUN npm installCOPY . /usr/src/appENV PORT 3000ARG DOCKER_ENVENV NODE_ENV=${DOCKER_ENV}RUN if [ "$DOCKER_ENV" = "stag" ] ; then  echo   your NODE_ENV for stage is $NODE_ENV;  \else  echo your NODE_ENV for dev is $NODE_ENV; \fi EXPOSE ${PORT}CMD [ "npm","run", "start" ]

when you build this Dockerfile with this command

docker build --build-arg DOCKER_ENV=stag -t test-node .

You will see at layer

 ---> Running in a6231eca4d0b your NODE_ENV for stage is stag

When you run this docker container and run this command your output will be

/usr/src/app # echo $NODE_ENVstag

Simplest Approch same image and but set environment variable at run time

Your Dockerfile

FROM node:alpineRUN mkdir -p /usr/src/appWORKDIR /usr/src/appCOPY package.json /usr/src/app/RUN npm installCOPY . /usr/src/appENV PORT 3000EXPOSE ${PORT}CMD [ "npm","run", "start" ]

Run this docker image with this command

docker build -t  test-node . docker run  --name test -e NODE_ENV=content-staging  -p 3000:3000 --rm -it test-node ash

So when you run this command at container you will see

/usr/src/app # echo $NODE_ENVcontent-staging

So this is how you can start your node application with NODE_ENV without setting environment variable at package.json. So if your nodejs configuration is based on NODE_ENV it should pick configuration according to NODE_ENV .

You can use the ENV instruction to get the environment variable as an environment variable inside container. Have an entry point script that injects the available environment variable (perhaps something as simple as sed) in place of a placeholder variable name that is in your package.json file. Then start your node application. Obviously this will require you to make a few changes to your Dockerfile in regards to entrypoint script etc.

That is how I have achieved such things in the past.