dotenv: Loads environment variables from dotenv files

[ configuration, library, mit, program ] [ Propose Tags ] [ Report a vulnerability ]

In most applications, configuration should be separated from code. While it usually works well to keep configuration in the environment, there are cases where you may want to store configuration in a file outside of version control.

Dotenv files have become popular for storing configuration, especially in development and test environments. In Ruby, Python and JavaScript there are libraries to facilitate loading of configuration options from configuration files. This library loads configuration to environment variables for programs written in Haskell.

To use, call loadFile from your application:

import Configuration.Dotenv
loadFile defaultConfig

This package also includes an executable that can be used to inspect the results of applying one or more Dotenv files to the environment, or for invoking your executables with an environment after one or more Dotenv files is applied.

See the Github page for more information on this package.


[Skip to Readme]

Flags

Manual Flags

NameDescriptionDefault
static

Creates static binary.

Disabled
dev

Turn on development settings.

Disabled

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

Downloads

Maintainer's Corner

Package maintainers

For package maintainers and hackage trustees

Candidates

  • No Candidates
Versions [RSS] 0.1.0.0, 0.1.0.1, 0.1.0.2, 0.1.0.3, 0.1.0.4, 0.1.0.5, 0.1.0.6, 0.1.0.7, 0.1.0.8, 0.1.0.9, 0.2.0.0, 0.3.0.0, 0.3.0.1, 0.3.0.2, 0.3.0.3, 0.3.1.0, 0.3.2.0, 0.3.3.0, 0.3.4.0, 0.4.0.0, 0.5.0.0, 0.5.0.1, 0.5.0.2, 0.5.1.0, 0.5.1.1, 0.5.2.0, 0.5.2.1, 0.5.2.2, 0.5.2.3, 0.5.2.4, 0.5.2.5, 0.6.0.1, 0.6.0.2, 0.6.0.3, 0.7.0.0, 0.8.0.0, 0.8.0.1, 0.8.0.2, 0.8.0.3, 0.8.0.4, 0.8.0.6, 0.8.0.7, 0.9.0.0, 0.9.0.1, 0.9.0.2, 0.9.0.3, 0.10.0.0, 0.10.0.1, 0.10.1.0, 0.11.0.0, 0.11.0.1, 0.11.0.2, 0.12.0.0 (info)
Change log CHANGELOG.md
Dependencies base (>=4.14 && <5.0), base-compat (>=0.4), containers, data-default-class (>=0.1.2 && <0.2), directory, dotenv, exceptions (>=0.8 && <0.11), megaparsec (>=7.0.1 && <10.0), mtl (>=2.2.2 && <2.4), optparse-applicative (>=0.11 && <0.19), process (>=1.6.3.0 && <1.7), shellwords (>=0.1.3.0), text [details]
Tested with ghc ==8.10, ghc ==9.0, ghc ==9.2, ghc ==9.4, ghc ==9.6
License MIT
Copyright 2015-Present Stack Builders Inc.
Author Justin Leitgeb
Maintainer hackage@stackbuilders.com
Category Configuration
Home page https://github.com/stackbuilders/dotenv-hs
Bug tracker https://github.com/stackbuilders/dotenv-hs/issues
Source repo head: git clone git@github.com:stackbuilders/dotenv-hs.git
Uploaded by camm at 2024-02-03T02:14:29Z
Distributions LTSHaskell:0.11.0.2, NixOS:0.11.0.2, Stackage:0.12.0.0
Reverse Dependencies 6 direct, 2 indirect [details]
Executables dotenv
Downloads 31021 total (231 in the last 30 days)
Rating (no votes yet) [estimated by Bayesian average]
Your Rating
  • λ
  • λ
  • λ
Status Docs available [build log]
Last success reported on 2024-02-03 [all 1 reports]

Readme for dotenv-0.12.0.0

[back to package description]

Build StatusHackage

All Contributors

Dotenv files for Haskell

In most applications, configuration should be separated from code. While it usually works well to keep configuration in the environment, there are cases where you may want to store configuration in a file outside of version control.

"Dotenv" files have become popular for storing configuration, especially in development and test environments. In Ruby, Python and Javascript there are libraries to facilitate loading of configuration options from configuration files. This library loads configuration to environment variables for programs written in Haskell.

Install

In most cases you will just add dotenv to your cabal file. You can also install the library and executable by invoking stack install dotenv or you can download the dotenv binaries from our releases page.

Usage

Set configuration variables in a file following the format below:

S3_BUCKET=YOURS3BUCKET
SECRET_KEY=YOURSECRETKEYGOESHERE

Then, calling Dotenv.load from your Haskell program reads the above settings into the environment:

import Configuration.Dotenv (loadFile, defaultConfig)
loadFile defaultConfig

After calling Dotenv.load, you are able to read the values set in your environment using standard functions from System.Environment or System.Environment.Blank (base >= 4.11.0.0), such as getEnv.

If your version of base is < 4.11.0.0, then setting an environment variable value to a blank string will remove the variable from the environment entirely.

Variable substitution

In order to use compound env vars use the following syntax within your env vars ${your_env_var}. For instance:

DATABASE=postgres://${USER}@localhost/database

Running it on the CLI:

$ dotenv "echo $DATABASE"
postgres://myusername@localhost/database

Command substitution

In order to use the standard output of a command in your env vars use the following syntax $(your_command). For instance:

DATABASE=postgres://$(whoami)@localhost/database

Running it on the CLI:

$ dotenv "echo $DATABASE"
postgres://myusername@localhost/database

Surrond with quotes

If your value starts with a character that produces a parse error (e.g. {) . Surround your value with quotes. You can also escape the quotes if they're inside your value. For example:

JSON_SQ='{"a":[1,2,3], "b": "\'asdf\'"}'
JSON_DQ="{\"a\":[1,2,3], \"b\": \"'asdf'\"}"

Run it:

$ dotenv "echo $JSON_SQ" | jq .a
[
  1,
  2,
  3
]

Configuration

The first argument to loadFile specifies the configuration. You can use defaultConfig which parses the .env file in your current directory and doesn't override your envs. You can also define your own configuration with the Config type.

False in configOverride means Dotenv will respect already-defined variables, and True means Dotenv will overwrite already-defined variables.

In the configPath you can write a list of all the dotenv files where are envs defined (e.g [".env", ".tokens", ".public_keys"]).

In the configExamplePath you can write a list of all the dotenv example files where you can specify which envs must be defined until running a program (e.g [".env.example", ".tokens.example", ".public_keys.example"]). If you don't need this functionality you can set configExamplePath to an empty list.

A False in the configVerbose means that Dotenv will not print any message when loading the envs. A True means that Dotenv will print a message when a variable is loaded.

When configDryRyn is True, Dotenv will print out the loaded environment variables without executing the program.

A False on allowDuplicates means that Dotenv will not allow duplicate keys, and instead it will throw an error. A True means that Dotenv will allow duplicate keys, and it will use the last one defined in the file (default behavior).

Advanced Dotenv File Syntax

You can add comments to your Dotenv file, on separate lines or after values. Values can be wrapped in single or double quotes. Multi-line values can be specified by wrapping the value in double-quotes, and using the "\n" character to represent newlines.

The spec file is the best place to understand the nuances of Dotenv file parsing.

Command-Line Usage

You can call dotenv from the command line in order to load settings from one or more dotenv file before invoking an executable:

$ dotenv -f mydotenvfile myprogram

The -f flag is optional, by default it looks for the .env file in the current working directory.

$ dotenv myprogram

Additionally, you can pass arguments and flags to the program passed to Dotenv:

$ dotenv -f mydotenvfile myprogram -- --myflag myargument

or:

$ dotenv -f mydotenvfile "myprogram --myflag myargument"

Also, you can use a --example flag to use dotenv-safe functionality so that you can have a list of strict envs that should be defined in the environment or in your dotenv files before the execution of your program. For instance:

$ cat .env.example
DOTENV=
FOO=
BAR=

$ cat .env
DOTENV=123

$ echo $FOO
123

This will fail:

$ dotenv -f .env --example .env.example "myprogram --myflag myargument"
> dotenv: The following variables are present in .env.example, but not set in the current environment, or .env: BAR

This will succeed:

$ export BAR=123 # Or you can do something like: "echo 'BAR=123' >> .env"
$ dotenv -f .env --example .env.example "myprogram --myflag myargument"

Hint: The env program in most Unix-like environments prints out the current environment settings. By invoking the program env in place of myprogram above you can see what the environment will look like after evaluating multiple Dotenv files.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Cristhian Motoche
Cristhian Motoche

💻
Justin S. Leitgeb
Justin S. Leitgeb

💻
Mark Karpov
Mark Karpov

💻
Juan Paucar
Juan Paucar

💻
Juan Pedro Villa Isaza
Juan Pedro Villa Isaza

💻
Daisuke Fujimura
Daisuke Fujimura

💻
William R. Arellano
William R. Arellano

💻
Diego Balseiro
Diego Balseiro

💻
Stefani Castellanos
Stefani Castellanos

💻
Götz
Götz

💻
Oleg Grenrus
Oleg Grenrus

💻
Sebastián Estrella
Sebastián Estrella

💻
Habib Alamin
Habib Alamin

💻
Franz Guzmán
Franz Guzmán

💻
Pat Brisbin
Pat Brisbin

💻
Alexander Goussas
Alexander Goussas

💻
Alexis Crespo
Alexis Crespo

💻
Andres Perez
Andres Perez

💻
Esteban Ibarra
Esteban Ibarra

💻
Fernanda Andrade
Fernanda Andrade

💻
Jorge Guerra Landázuri
Jorge Guerra Landázuri

💻
MATSUBARA Nobutada
MATSUBARA Nobutada

💻
Wojtek Mach
Wojtek Mach

💻

This project follows the all-contributors specification. Contributions of any kind welcome!

License

MIT, see the LICENSE file.

Contributing

Do you want to contribute to this project? Please take a look at our contributing guideline to know how you can help us build it.


Stack Builders Check out our libraries | Join our team