by Erisan Olasheni

With Replit, you can create an.env file to safely store your secrets. This means you can safely share your code, without sharing your secrets.env Files.env files are used for declaring environment variables. On Replit,.env files are only visible to the owner of the repl. Environment variables come to rescue in this case. We create a.env file and store the connection string in variables and exclude them from public sharing. Environment variables in.env file is a bit more secure (controversial topic) then hard coding.

Have you ever found yourself in a situation where you needed custom environment variables for different development stages of your app? Here is a one-line solution.

Development has been much easier since the invention of the .env file. You can easily set your environment variables and values with the syntax ENV_VARIABLE=VALUE and boom! These variables got loaded as your environment variables, making it possible to get quick access to them:

In case you are still wondering what all this means, well, you are probably new to the .env file. It’s actually a simple configuration text file that is used to define some variables you want to pass into your application’s environment.

This file needs a something like a parser to make it work. The parser reads the variable definitions one-by-one and parses them to the environment. It uses the format ENV_VARIABLE=VALUE (in the case of Node.js: process.env[ENV_VARIABLE]=VALUE).

Of course, this is not a built-in feature in Node.js. You have to engineer it with a popular module called dotenv.

It’s a nice workaround, as it has really made development easier between co-developers and across the dev community as a whole. I personally had been using the dotenv module, until I got stranded trying to get a solution that could make me use a different configuration file for a particular environment. That would be even cooler…right? Yes! But unfortunately, the dotenvmodule doesn’t provide us with this goody.

So what’s next? We need this thing to make development and testing easier across different development stages!

How about custom .env files for different environment stages?

Don’t you think that would be a good solution? Defining custom environment variables by just creating a .env.envname file? Cool! That is what custom-env has come to do.

Custom env is a library built to make development easier by allowing multiple .env configuration for different environments. This is done by loading environment variables from a .env.envname file into the node’s process.env object.

Installation

Just grab it with the following command: Hazmat id user manual.

Usage

By default, custom-env picks the .env file for your dev stage. However, to customize for a different stage, add the name as a suffix as in .env.envname.

Example

We can define a custom environment variable for a staging development.

Create a .env.staging file
Define your variables

Access your variables

Expected Output

That’s it, pretty easy. Feel free to define more variables for different stages you think you have, like:

.env.testing, .env.staging, .env.server1, .env.server2, .env.localhost

Set to the Current Environment

You can tell custom-env to use a configuration that matches your current development stage by passing trueto the env()method.

Example

File: index.js

Now let’s define a staging configuration file:

File: .env.staging

Now let’s serve node with the staging environment:

Expected Output

There you go!

Full Documentation

Env Files For Appraisal

For the full documentation of custom-env, visit the npm pagehttps://www.npmjs.com/package/custom-env

Source Code

You can get or contribute to the custom-envsource code at https://github.com/erisanolasheni/custom-env

Happy Coding!

Building Docker images and configuring your dockerized apps doesn’t have to bea try-fail-repeat Google extravaganza.This article will help you work with Docker ARG, ENV, env_file and .env files with confidence.

The only prerequisite: make sure that you’re comfortable with the basics of Docker.

Create .env File Ubuntu

Read on and you will understand how to configure your Docker images and dockerized apps with ease - with the power of Docker build-time variables, environment variables and docker-compose templating.

Frequent Misconceptions

This is a long, in-depth read. Let’s start with something you can use right now, without having to read the whole thing!

Here’s a list of easy takeaways:

The .env file, is only used during a pre-processing step when working with docker-compose.yml files. Dollar-notation variables like $HI are substituted for values contained in an “.env” named file in the same directory.
ARG is only available during the build of a Docker image (RUN etc), not after the image is created and containers are started from it (ENTRYPOINT, CMD). You can use ARG values to set ENV values to work around that.
ENV values are available to containers, but also RUN-style commands during the Docker build starting with the line where they are introduced.
If you set an environment variable in an intermediate container using bash (RUN export VARI=5 && …) it will not persist in the next command. There’s a way to work around that.
An env_file, is a convenient way to pass many environment variables to a single command in one batch. This should not be confused with a .env file.
Setting ARG and ENV values leaves traces in the Docker image. Don’t use them for secrets which are not meant to stick around (well, you kinda can with multi-stage builds).

An Overview

Alright, let’s get started with the details.The guide is split up into the following topics:

Feel free to jump right to the one you need right now. However, you’ll getthe best result if you read through them all thoroughly.

The Dot-Env File (.env)

This one is quite simple, and only confusing because of bad examples andsimilar concepts using the same format, sounding a lot like it. What’s importantis the dot in front of env - .env, not an “env_file”.

If you have a file named .env in your project, it’s only used to put valuesinto the docker-compose.yml file which is in the same folder. Those are usedwith Docker Compose and Docker Stack. It has nothing to do with ENV, ARG, or anything Docker-specific explained above. It’s exclusively a docker-compose.yml thing.

The values in the .env file are written in the following notation:

Those key-value pairs, are used to substitute dollar-notation variables inthe docker-compose.yml file. It’s kind of a pre-processing step, and theresulting temporary file is used. This is a nice way to avoid hard-codingvalues. You can also use this to set the values for environment variables,by substituting the string, but that does not happen automatically.

Here is an example docker-compose.yml file, relying on values provided from a.env file:

Hint:When working with an .env file, you can debug your docker-compose.yml files quite easily.Just type docker-compose config. This way you’ll see how the docker-compose.yml file content looks after the substitution step has been performed without running anything else.

Here’s a gotcha you should know: environment variables on your host can override the values in your .env file. Read more here.

Create .env File Python

ARG and ENV Availability

When using Docker, we distinguish between two different types of variables -ARG and ENV.

ARG are also known as build-time variables. They are only availablefrom the moment they are ‘announced’ in the Dockerfile with an ARG instructionup to the moment when the image is built. Running containers can’t accessvalues of ARG variables. This also applies to CMD and ENTRYPOINT instructionswhich just tell what the conta

Create An Env File