How to set different ENV variable when building and deploying Docker Image to Cloud Run?

You can't achieve this without a cloudbuild.yaml file. The command gcloud builds submit --tag ... doesn't accept extra docker parameter.

Here an example of configuration

FROM node:12-slim

ARG SERVER_CONF=PROD
ENV SERVER_ENV=$SERVER_CONF

WORKDIR /

COPY ./package.json ./package.json
COPY ./distApp ./distApp
COPY ./distService ./distService
COPY ./public ./public

RUN npm install

ENTRYPOINT npm start

I created a build argument SERVER_CONF. Your ENV will take this value at build time. The default value is PROD

Now your cloudbuild.yaml file

step:
  - name: 'gcr.io/cloud-builders/docker'
    args: ['build', '--tag=gcr.io/PROJECT-ID/helloworld', '--build-arg="SERVER_CONF=$_SERVER_CONF"', '.']
  - name: 'gcr.io/cloud-builders/docker'
    args: ['push', 'gcr.io/PROJECT-ID/helloworld']
substitutions:
  _SERVER_CONFPROD: PROD

Use substitution variables to change the environment. Not that here you can also set a default value, that override your Dockerfile value. Take care of this!

You can also set the tag as substitution variable if you want

Eventually, how to call your Cloud Build

# With default server conf (no substitution variables, the the file default)
gcloud builds submit

# With defined server conf
gcloud builds submit --substitutions=_SERVER_CONF=TEST