I am deploying a create-react-app Service onto Google Cloud Run using a Dockerfile, but I want to move away from declaring env variables in a .env file, and instead, declare them on Google Cloud Run's Dashboard like so:

However, when I call the env var using
console.log("REDIRECT", process.env.REACT_APP_REDIRECT_URI)
null is returned for any env variable I try to reference. Is there another step to access these variables that I am missing?
Here is my Dockerfile:
FROM node:10-alpine as react-build
WORKDIR /app
COPY . ./
RUN yarn
RUN yarn build
FROM nginx:alpine
COPY nginx.conf /etc/nginx/conf.d/configfile.template
ENV PORT 8080
ENV HOST 0.0.0.0
RUN sh -c "envsubst '\$PORT' < /etc/nginx/conf.d/configfile.template > /etc/nginx/conf.d/default.conf"
COPY --from=react-build /app/build /usr/share/nginx/html
EXPOSE 8080
CMD ["nginx", "-g", "daemon off;"]