Pass environment variable into a Vue App at runtime - docker

Question

How can I access environment variables in Vue, that are passed to the container at runtime and not during the build?
Stack is as follows:
VueCLI 3.0.5
Docker
Kubernetes
There are suggested solutions on stackoverflow and elsewhere to use .env file to pass variables (and using mode) but that's at build-time and gets baked into the docker image.
I would like to pass the variable into Vue at run-time as follows:
Create Kubernetes ConfigMap (I get this right)
Pass ConfigMap value into K8s pod env variable when running deployment yaml file (I get this right)
Read from env variable created above eg. VUE_APP_MyURL and do something with that value in my Vue App (I DO NOT get this right)
I've tried the following in helloworld.vue:
<template>
<div>{{displayURL}}
<p>Hello World</p>
</div>
</template>
<script>
export default {
data() {
return {
displayURL: ""
}
},
mounted() {
console.log("check 1")
this.displayURL=process.env.VUE_APP_ENV_MyURL
console.log(process.env.VUE_APP_ENV_MyURL)
console.log("check 3")
}
}
</script>
I get back "undefined" in the console log and nothing showing on the helloworld page.
I've also tried passing the value into a vue.config file and reading it from there. Same "undefined" result in console.log
<template>
<div>{{displayURL}}
<p>Hello World</p>
</div>
</template>
<script>
const vueconfig = require('../../vue.config');
export default {
data() {
return {
displayURL: ""
}
},
mounted() {
console.log("check 1")
this.displayURL=vueconfig.VUE_APP_MyURL
console.log(vueconfig.VUE_APP_MyURL)
console.log("check 3")
}
}
</script>
With vue.config looking like this:
module.exports = {
VUE_APP_MyURL: process.env.VUE_APP_ENV_MyURL
}
If I hardcode a value into VUE_APP_MyURL in the vue.config file it shows successfully on the helloworld page.
VUE_APP_ENV_MyURL is successfully populated with the correct value when I interrogate it: kubectl describe pod
process.env.VUE_APP_MyURL doesn't seem to successfully retrieve the value.
For what it is worth... I am able to use process.env.VUE_APP_3rdURL successfully to pass values into a Node.js app at runtime.

Answer 1

Create a file config.js with your desired configuration. We will use that later to create a config map that we deploy to Kubernetes. Put it into your your Vue.js project where your other JavaScript files are. Although we will exclude it later from minification, it is useful to have it there so that IDE tooling works with it.
const config = (() => {
return {
"VUE_APP_ENV_MyURL": "...",
};
})();
Now make sure that your script is excluded from minification. To do that, create a file vue.config.js with the following content that preserves our config file.
const path = require("path");
module.exports = {
publicPath: '/',
configureWebpack: {
module: {
rules: [
{
test: /config.*config\.js$/,
use: [
{
loader: 'file-loader',
options: {
name: 'config.js'
},
}
]
}
]
}
}
}
In your index.html, add a script block to load the config file manually. Note that the config file won't be there as we just excluded it. Later, we will mount it from a ConfigMap into our container. In this example, we assume that we will mount it into the same directory as our HTML document.
<script src="<%= BASE_URL %>config.js"></script>
Change your code to use our runtime config:
this.displayURL = config.VUE_APP_ENV_MyURL || process.env.VUE_APP_ENV_MyURL
In Kubernetes, create a config map that uses the content your config file. Of course, you wanna read the content from your config file.
apiVersion: v1
kind: ConfigMap
metadata:
...
data:
config.js: |
var config = (() => {
return {
"VUE_APP_ENV_MyURL": "...",
};
})();
Reference the config map in your deployment. This mounts the config map as a file into your container. The mountPath Already contains our minified index.html. We mount the config file that we referenced before.
apiVersion: apps/v1
kind: Deployment
metadata:
...
spec:
...
template:
...
spec:
volumes:
- name: config-volume
configMap:
name: ...
containers:
- ...
volumeMounts:
- name: config-volume
mountPath: /usr/share/nginx/html/config.js
subPath: config.js
Now you can access the config file at <Base URL>/config.js and you should see the exact content that you put into the ConfigMap entry. Your HTML document loads that config map as it loads the rest of your minified Vue.js code. Voila!

Answer 2

I am adding my working solution here, for those who are still having trouble. I do think that #Hendrik M Halkow 's answer is more elegant, though I couldn't manage to solve it using that, simply just because of my lack of expertise in webpack and Vue.I just couldn't figure out where to put the config file and how to refer it.
My approach is to make use of the environment variables with constants (dummy values) to build it for production, then replace that constants in the image using a custom entrypoint script. The solution goes like this.
I have encapsulated all configs into one file called app.config.js
export const clientId = process.env.VUE_APP_CLIENT_ID
export const baseURL = process.env.VUE_APP_API_BASE_URL
export default {
clientId,
baseURL,
}
This is used in the project just by looking up the value from config file.
import { baseURL } from '#/app.config';
Then I am using standard .env.[profile] files to set environment variables.
e.g. the .env.development
VUE_APP_API_BASE_URL=http://localhost:8085/radar-upload
VUE_APP_CLIENT_ID=test-client
Then for production I set string constants as values.
e.g. the .env.production
VUE_APP_API_BASE_URL=VUE_APP_API_BASE_URL
VUE_APP_CLIENT_ID=VUE_APP_CLIENT_ID
Please not here the value can be any unique string. Just to keep the readability easier, I am just replacing the environment variable name as the value. This will just get compiled and bundled similar to development mode.
In my Dockerfile, I add an entrypoint that can read those constants and replace it will environment variable values.
My Dockerfile looks like this (this is pretty standard)
FROM node:10.16.3-alpine as builder
RUN mkdir /app
WORKDIR /app
COPY package*.json /app/
RUN npm install
COPY . /app/
RUN npm run build --prod
FROM nginx:1.17.3-alpine
# add init script
COPY ./docker/nginx.conf /etc/nginx/nginx.conf
WORKDIR /usr/share/nginx/html
COPY --from=builder /app/dist/ .
COPY ./docker/entrypoint.sh /entrypoint.sh
# expose internal port:80 and run init.sh
EXPOSE 80
ENTRYPOINT ["/entrypoint.sh"]
CMD ["nginx", "-g", "daemon off;"]
Then create a ./docker/entrypoint.sh file as below.
#!/bin/sh
ROOT_DIR=/usr/share/nginx/html
# Replace env vars in JavaScript files
echo "Replacing env constants in JS"
for file in $ROOT_DIR/js/app.*.js* $ROOT_DIR/index.html $ROOT_DIR/precache-manifest*.js;
do
echo "Processing $file ...";
sed -i 's|VUE_APP_API_BASE_URL|'${VUE_APP_API_BASE_URL}'|g' $file
sed -i 's|VUE_APP_CLIENT_ID|'${VUE_APP_CLIENT_ID}'|g' $file
done
echo "Starting Nginx"
nginx -g 'daemon off;'
This enables me to have runtime configurable image that I can run on many environments. I know it is a bit of a hack. But have seen many people do it this way.
Hope this helps someone.

Answer 3

Create config file
In public folder: public/config.js
const config = (() => {
return {
"VUE_CONFIG_APP_API": "...",
};
})();
Update index.html
Update public/index.html to contain following at the end of head:
<!-- docker configurable variables -->
<script src="<%= BASE_URL %>config.js"></script>
There is no need to update vue.config.js as we are using the public folder for configuration.
ESLint
ESLint would give us error of usage of undefined variable. Therefore we define global variable in .eslintrc.js file:
globals: {
config: "readable",
},
Usage
Eg. in the store src/store/user.js
export const actions = {
async LoadUsers({ dispatch }) {
return await dispatch(
"axios/get",
{
url: config.VUE_CONFIG_APP_API + "User/List",
},
{ root: true }
);
},
...
K8S ConfigMap:
apiVersion: v1
kind: ConfigMap
metadata:
name: fe-config
namespace: ...
data:
config.js: |
var config = (() => {
return {
"VUE_CONFIG_APP_API": "...",
};
})();
Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
...
spec:
...
template:
...
spec:
volumes:
- name: config-volume
configMap:
name: fe-config
containers:
- ...
volumeMounts:
- name: config-volume
mountPath: /usr/share/nginx/html/config.js
subPath: config.js

Answer 4

I had the same problem in my current project and found out that it is not possible to access environment variables at runtime at the moment so I end up with the solution of creating .env files or local environment variables that, as you said, are used at the build time.

Answer 5

I recently created a set of plugins to solve this problem elegantly:
No global namespace pollution.
No import statement is required.
Almost zero configuration.
Out-of-the-box support for Vue CLI (also works with Webpack, Rollup and Vite, CSR, SSR and SSG, and unit testing tools. Powered by Unplugin and Babel).
You can access environment variables (heavily inspired by Vite) this way:
// src/index.js
console.log(`Hello, ${import.meta.env.HELLO}.`);
During production, it will be temporarily replaced with a placeholder:
// dist/index.js
console.log(`Hello, ${"__import_meta_env_placeholder__".HELLO}.`);
Finally, you can use built-in script to replace placeholders with real environment variables in your system (e.g., read environment variables in your k8s pod):
// dist/index.js
console.log(`Hello, ${{ HELLO: "import-meta-env" }.HELLO}.`);
// > Hello, import-meta-env.
You can see more info at https://iendeavor.github.io/import-meta-env/ .
And there is a Docker setup example and Vue CLI setup example.
Hope this helps someone who needs this.

Answer 6

I got it to work with the solution proposed by #Hendrik M Halkow.
But I stored the config.js in the static folder. By doing that, I don't have to care about not minifying the file.
Then include it like this:
<script src="<%= BASE_URL %>static/config.js"></script>
and use this volume mount configuration:
...
volumeMounts:
- name: config-volume
mountPath: /usr/share/nginx/html/static/config.js
subPath: config.js

Answer 7

If you are using VueJs3 + Vite3 + TypeScript, you can do this:
create app.config.ts (not JS)
export const clientId = import.meta.env.VITE_CLIENT_ID
export const baseURL = import.meta.env.VITE_API_BASE_URL
export default {
clientId,
baseURL,
}
Replace values in assets subdir: (improved shell script)
#!/bin/sh
# #see https://stackoverflow.com/questions/18185305/storing-bash-output-into-a-variable-using-eval
ROOT_DIR=/usr/share/nginx/html
# Replace env vars in JavaScript files
echo "Replacing env constants in JS"
keys="VITE_CLIENT_ID
VITE_API_BASE_URL"
for file in $ROOT_DIR/assets/index*.js* ;
do
echo "Processing $file ...";
for key in $keys
do
value=$(eval echo \$$key)
echo "replace $key by $value"
sed -i 's#'"$key"'#'"$value"'#g' $file
done
done
echo "Starting Nginx"
nginx -g 'daemon off;'
In the Dockerfile don't forget "RUN chmod u+x"
# build
FROM node:lts-alpine as build-stage
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build
# production
FROM nginx:stable-alpine as production-stage
COPY --from=build-stage /app/dist /usr/share/nginx/html
COPY ./docker/nginx.conf /etc/nginx/conf.d/default.conf
COPY ./docker/entrypoint.sh /entrypoint.sh
COPY ./docker/entrypoint.sh /usr/local/bin/
RUN chmod u+x /usr/local/bin/entrypoint.sh
EXPOSE 80
ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
CMD ["nginx", "-g", "daemon off;"]
then you be able to import it in any TypeScript file in the project
import { baseURL } from '#/app.config';
#see update of NehaM response: Pass environment variable into a Vue App at runtime