#Docker and Next js env

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finite elm
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I have a Next js app and a docker image , the problem is env varaible is not present on dockaer container , how i could fix that , also i have two enviroment test and env

cold graniteBOT
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Hi @finite elm. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

#

In Next.js, environment variables are only available on the server by default. If you want to expose an environment variable to the browser, you need to prefix it with NEXT_PUBLIC_. However, these public environment variables will be inlined into the JavaScript bundle during next build source (https://nextjs.org/docs/app/building-your-application/deploying#environment-variables).

To read runtime environment variables, it's recommended to use getServerSideProps or incrementally adopt the App Router. With the App Router, you can safely read environment variables on the server during dynamic rendering. This allows you to use a singular Docker image that can be promoted through multiple environments with different values source (https://nextjs.org/docs/app/building-your-application/configuring/environment-variables#runtime-environment-variables).

If you're having trouble with environment variables in a Docker container, it could be due to the location of your .env files. They need to be in the same folder as the server.js file source (https://github.com/vercel/next.js/issues/59130).

Here's an example of how you might use an environment variable in your Next.js app:

import { unstable_noStore as noStore } from 'next/cache'
 
export default function Component() {
  noStore()
  // cookies(), headers(), and other dynamic functions
  // will also opt into dynamic rendering, meaning
  // this env variable is evaluated at runtime
  const value = process.env.MY_VALUE
  // ...
}

If you're using Docker, you might need to copy your .env files into the Docker container. You can do this in your Dockerfile with a command like COPY .env* ./. This will copy all files in your project directory that start with .env into the Docker container.

#

Remember, if you want to use runtime environment variables, they must not be prefixed with NEXT_PUBLIC_. The NEXT_PUBLIC_ prefix is only for variables that you want to expose to the browser source (https://github.com/vercel/next.js/issues/61580).

If you're still having trouble, it might be helpful to see the output of env inside your Docker container, and to check the contents of the directory where your server.js file is located with ls -la source (https://github.com/vercel/next.js/issues/59130).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@finite elm kapa.ai is still learning and improving, please let us know how it did by reacting below

finite elm
#

i want to use runtime envs

i pass .env.local into my gitignore file

and wants to pass these varaible when runing the container

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@cold granite i want to use runtime envs

i pass .env.local into my gitignore file

and wants to pass these varaible when runing the container

cold graniteBOT
#

Let me check the knowledge base for you. One moment! :books:

#

If you want to use runtime environment variables in your Next.js application running in a Docker container, you can pass these variables when running the container using the -e option with the docker run command.

However, keep in mind that by default, environment variables are only available on the server in Next.js. If you want to expose an environment variable to the browser, you need to prefix it with NEXT_PUBLIC_. But these public environment variables will be inlined into the JavaScript bundle during next build source (https://nextjs.org/docs/app/building-your-application/deploying#environment-variables).

To read runtime environment variables, it's recommended to use getServerSideProps or incrementally adopt the App Router. With the App Router, you can safely read environment variables on the server during dynamic rendering source (https://nextjs.org/docs/app/building-your-application/configuring/environment-variables#runtime-environment-variables).

Here's an example of how you might use an environment variable in your Next.js app:

import { unstable_noStore as noStore } from 'next/cache'
 
export default function Component() {
  noStore()
  // cookies(), headers(), and other dynamic functions
  // will also opt into dynamic rendering, meaning
  // this env variable is evaluated at runtime
  const value = process.env.MY_VALUE
  // ...
}

If you're using Docker, you might need to copy your .env files into the Docker container. You can do this in your Dockerfile with a command like COPY .env* ./. This will copy all files in your project directory that start with .env into the Docker container.

#

Remember, if you want to use runtime environment variables, they must not be prefixed with NEXT_PUBLIC_. The NEXT_PUBLIC_ prefix is only for variables that you want to expose to the browser source (https://github.com/vercel/next.js/issues/61580).

If you're still having trouble, it might be helpful to see the output of env inside your Docker container, and to check the contents of the directory where your server.js file is located with ls -la source (https://github.com/vercel/next.js/issues/59130).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@finite elm kapa.ai is still learning and improving, please let us know how it did by reacting below

finite elm
#

@cold granite i didnt understand how to use Next envs on docker container

cold graniteBOT
#

Let me check the knowledge base for you. One moment! :books:

#

To use Next.js environment variables in a Docker container, you need to pass these variables when running the Docker container. Here's a step-by-step guide:

  1. Define your environment variables in a .env.local file in your Next.js project. This file should be in your .gitignore to prevent it from being committed to your repository.
# .env.local
MY_VALUE=my-secret-value
  1. In your Next.js application, you can access these environment variables using process.env. For example:
// In your Next.js application
const value = process.env.MY_VALUE

  1. When you're building your Docker image, you don't need to do anything special for these environment variables. They're not used during the build process, so they don't need to be included in the image.

  2. When you run your Docker container, you can pass in the environment variables using the -e option with the docker run command. For example:

docker run -e MY_VALUE=my-secret-value -p 3000:3000 my-next-app

In this command, MY_VALUE=my-secret-value is setting the MY_VALUE environment variable to my-secret-value inside the Docker container. You can pass multiple environment variables by using the -e option multiple times.

Remember, by default, environment variables are only available on the server in Next.js. If you want to expose an environment variable to the browser, you need to prefix it with NEXT_PUBLIC_. But these public environment variables will be inlined into the JavaScript bundle during next build source (https://nextjs.org/docs/app/building-your-application/deploying#environment-variables).