The Problem with Environment Variables when Creating Docker Image in EC2 with NestJS: A Comprehensive Guide

As a developer, you’re probably no stranger to the concept of environment variables. They’re essential for storing sensitive information, such as API keys or database credentials, that your application needs to function properly. However, when it comes to creating a Docker image in an EC2 instance with NestJS, things can get a bit more complicated. In this article, we’ll dive into the problem with environment variables in this specific scenario and provide a step-by-step guide on how to overcome it.

What’s the Problem?

When you create a Docker image, you’re essentially creating a snapshot of your application and its dependencies. However, environment variables are not included in this snapshot by default. This means that when you run your Docker container, it won’t have access to the environment variables you set in your EC2 instance.

This can lead to a number of issues, including:

• Database connections failing because the database credentials are not available
• API keys not being recognized, resulting in authentication errors
• Sensitive information being exposed in your Docker image or container

Why Do Environment Variables Get Lost?

To understand why environment variables get lost when creating a Docker image, let’s take a step back and look at how Docker works.

When you run a Docker command, such as docker build or docker run, Docker creates a new process that runs in isolation from the host system. This means that the new process doesn’t inherit the environment variables from the host system.

In the case of an EC2 instance, the environment variables are set at the instance level, not at the container level. When you create a Docker image, the environment variables from the EC2 instance are not included in the image.

Solutions to the Problem

Now that we’ve identified the problem, let’s explore some solutions to overcome it.

Solution 1: Using Environment Files

One way to pass environment variables to your Docker container is to use environment files. An environment file is a text file that contains key-value pairs of environment variables.

Here’s an example of how to create an environment file:

# envfile
DATABASE_URL=postgres://user:password@localhost:5432/database
API_KEY=your_api_key_here

To use an environment file with your Docker image, you can add the following command to your Dockerfile:

FROM node:14

WORKDIR /app

COPY . .

ENVFILE envfile

RUN npm install

CMD ["npm", "run", "start"]

In this example, the ENVFILE command is used to specify the environment file. The environment variables from the file will be set when the Docker container is started.

Solution 2: Using Docker Compose

Docker Compose is a tool that allows you to define and run multi-container Docker applications. One of the benefits of using Docker Compose is that it allows you to pass environment variables from the host system to the containers.

Here’s an example of how to use Docker Compose to pass environment variables:

version: '3'

services:
  app:
    build: .
    environment:
      - DATABASE_URL=postgres://user:password@localhost:5432/database
      - API_KEY=your_api_key_here
    ports:
      - "3000:3000"

In this example, the environment section is used to specify the environment variables that should be passed to the container.

Solution 3: Using AWS Parameter Store

AWS Parameter Store is a service that allows you to store sensitive information, such as database credentials and API keys, securely. You can use AWS Parameter Store to store your environment variables and retrieve them in your Docker container.

Here’s an example of how to use AWS Parameter Store with your Docker image:

FROM node:14

WORKDIR /app

COPY . .

RUN npm install

RUN aws ssm get-parameters-by-path --path /my/app/parameters --query 'Parameters[]|{Name,Value}' --output text > envfile

CMD ["npm", "run", "start"]

In this example, the aws ssm get-parameters-by-path command is used to retrieve the environment variables from AWS Parameter Store and store them in an environment file.

Best Practices for Environment Variables

When working with environment variables, it’s essential to follow best practices to ensure the security and integrity of your application. Here are a few tips to keep in mind:

1. Use secure storage for sensitive information: Avoid hardcoding sensitive information, such as API keys or database credentials, in your code or environment files. Instead, use a secure storage solution like AWS Parameter Store or HashiCorp’s Vault.
2. Use environment variables wisely: Only set environment variables that are necessary for your application to function. Avoid setting unnecessary environment variables that could potentially expose sensitive information.
3. Rotate environment variables regularly: Rotate your environment variables regularly to minimize the risk of exposure in case of a security breach.
4. Use a consistent naming convention: Use a consistent naming convention for your environment variables to avoid confusion and errors.

Environment Variable	Description	Example
DATABASE_URL	Database connection URL	postgres://user:password@localhost:5432/database
API_KEY	API key for authentication	your_api_key_here

Conclusion

In this article, we’ve explored the problem with environment variables when creating a Docker image in an EC2 instance with NestJS. We’ve covered three solutions to overcome this problem, including using environment files, Docker Compose, and AWS Parameter Store. We’ve also discussed best practices for environment variables to ensure the security and integrity of your application.

By following the instructions and guidelines outlined in this article, you should be able to create a Docker image that includes environment variables from your EC2 instance. Remember to follow best practices for environment variables to minimize the risk of exposure and ensure the security of your application.

We hope you found this article helpful. If you have any questions or comments, please feel free to leave them below.

Happy coding!

Frequently Asked Question

Get the scoop on the most pressing issues when it comes to environment variables in Docker images on EC2 with NestJS – we’ve got you covered!