Gatsby: Environment variables .env return undefined - docker

Question

I am working on a static website using Gatsby for the development and Nginx for serving the static files.
I am also using Docker for the deployment to test and production and Traefik for routing traffic to the docker container of the application.
I have an environment variable which I defined in the application file, and that environment variable is called from a .env file in the root folder of the application.
However, when that environment variable is invoked in the application, it throws an error:
undefined
Here's the code:
Dockerfile
# Set base image
FROM node:latest AS builder
# Set working directory
WORKDIR /app
# Copy package.json and install packages
COPY package.json .
RUN npm install
# Copy other project files and build
COPY . ./
RUN npm run build
# Set nginx image
FROM nginx:latest
# Nginx config
RUN rm -rf /etc/nginx/conf.d/default.conf
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf
# Static build
COPY --from=builder /app/public /usr/share/nginx/html
# Set working directory
WORKDIR /usr/share/nginx/html
# Start Nginx server
CMD ["/bin/bash", "-c", "nginx -g \"daemon off;\""]
.env
GATSBY_API_URL=https://myapi.mywebsite.com
docker-compose.yml
version: "3"
services:
web:
image: my-website
build:
context: .
dockerfile: Dockerfile
environment:
GATSBY_API_URL: ${GATSBY_API_URL}
expose:
- "80"
labels:
- traefik.enable=true
- traefik.http.routers.my-website.rule=Host(`my-website.com`)
restart: always
volumes:
- .:/app
networks:
default:
external:
name: traefik-proxy
index.js
const onSubmit = async (values) => {
try {
const res = await axios.post(`${process.env.GATSBY_API_URL}/api/EmployeeDetail/verify`, values)
// console.log(res, 'verify endpoint');
if( res.data.requestSuccessful === true ) {
dispatchVerifyData({
type : 'UPDATE_VERIFY_DATA',
verifyData: {
res: res.data.responseData,
loanType: values.loanType
}
})
handleNext()
} else {
setIsSuccessful({
status: false,
message: res.data.message
})
}
} catch (error) {
//error state Unsuccessful
console.log(error, 'error')
setIsSuccessful({
status: false,
})
}
}
.dockerignore
node_modules
npm-debug.log
.DS_Store
.bin
.git
.gitignore
.bundleignore
.bundle
.byebug_history
.rspec
tmp
log
test
config/deploy
public/packs
public/packs-test
yarn-error.log
coverage/
.env
.env.production
Nginx default.conf
server {
listen 80;
add_header Cache-Control no-cache;
location / {
root /usr/share/nginx/html;
index index.html index.htm;
try_files $uri $uri/ /index.html;
expires -1;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
}
I can't still seem to tell what is the cause of the issue that causes the application to return an undefined error whenever the environment variable is invoked. Any form of help will be highly appreciated.

Answer 1

I finally figured it after some long hours of debugging with my colleagues.
Here are a few things I learnt:
Firstly, by default, Gatsby supports 2 environments:
Development. If you run gatsby develop, then you will be in the development environment.
Production. If you run gatsby build or gatsby serve, then you will be in the production environment.
If you note, however, we are running npm run build in our Dockerfile which is equivalent to gatsby build, so this informs the application that we are running in the production. environment.
Secondly, defining Environment Variables for Client-side JavaScript
For Project Env Vars that you want to access in client-side browser JavaScript, you can define an environment config file, .env.development and/or .env.production, in your root folder. Depending on your active environment, the correct one will be found and its values embedded as environment variables in the browser JavaScript.
In otherwords, we will need to rename our environment config file from .env to .env.production to allow the Gatsby application to recognize it in our production environment.
Thirdly, defining Environment Variables using prefixes
In addition to these Project Environment Variables defined in .env.* files, you could also define OS Env Vars. OS Env Vars which are prefixed with GATSBY_ will become available in browser JavaScript.
If you note very well we are already defining this in our .env config file as - GATSBY_API_URL=https://myapi.mywebsite.com, so we have no issues with that.
Fourthly, removing the env. config files from .dockerignore
If we observe clearly how the values of environment variables are embedded in the browser Javascript for Client-side JavaScript, you will see that it is done during build time and not run time.
Therefore, we need to remove the .env.* config files from .dockerignore and also remove the environment option in the docker-compose.yml file, since it is unnecessary anymore because we don't embed the values of the environment variables during the run time.
So our code will look like this now:
Dockerfile
# Set base image
FROM node:latest AS builder
# Set working directory
WORKDIR /app
# Copy package.json and install packages
COPY package.json .
RUN npm install
# Copy other project files and build
COPY . ./
RUN npm run build
# Set nginx image
FROM nginx:latest
# Nginx config
RUN rm -rf /etc/nginx/conf.d/default.conf
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf
# Static build
COPY --from=builder /app/public /usr/share/nginx/html
# Set working directory
WORKDIR /usr/share/nginx/html
# Start Nginx server
CMD ["/bin/bash", "-c", "nginx -g \"daemon off;\""]
.env.production
GATSBY_API_URL=https://myapi.mywebsite.com
docker-compose.yml
version: "3"
services:
web:
image: my-website
build:
context: .
dockerfile: Dockerfile
expose:
- "80"
labels:
- traefik.enable=true
- traefik.http.routers.my-website.rule=Host(`my-website.com`)
restart: always
volumes:
- .:/app
networks:
default:
external:
name: traefik-proxy
index.js
const onSubmit = async (values) => {
try {
const res = await axios.post(`${process.env.GATSBY_API_URL}/api/EmployeeDetail/verify`, values)
// console.log(res, 'verify endpoint');
if( res.data.requestSuccessful === true ) {
dispatchVerifyData({
type : 'UPDATE_VERIFY_DATA',
verifyData: {
res: res.data.responseData,
loanType: values.loanType
}
})
handleNext()
} else {
setIsSuccessful({
status: false,
message: res.data.message
})
}
} catch (error) {
//error state Unsuccessful
console.log(error, 'error')
setIsSuccessful({
status: false,
})
}
}
.dockerignore
node_modules
npm-debug.log
.DS_Store
.bin
.git
.gitignore
.bundleignore
.bundle
.byebug_history
.rspec
tmp
log
test
config/deploy
public/packs
public/packs-test
yarn-error.log
coverage/
Nginx default.conf
server {
listen 80;
add_header Cache-Control no-cache;
location / {
root /usr/share/nginx/html;
index index.html index.htm;
try_files $uri $uri/ /index.html;
expires -1;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
}
That's all.
I hope this helps