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https://github.com/rillke/docker-env-file-update

Some handy scripts handling the update of .env files consumed by Docker during deployment when checking out a different version
https://github.com/rillke/docker-env-file-update

bash-script deployment docker-compose env environment-variables git-hooks synchronization update

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Some handy scripts handling the update of .env files consumed by Docker during deployment when checking out a different version

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# Update scripts for docker(-compose) env files [![Build Status](https://travis-ci.org/Rillke/Docker-env-file-update.svg?branch=master)](https://travis-ci.org/Rillke/Docker-env-file-update)



Supplying environment variables through files is a convenient way to manage a larger number of configuration options applied through environment variables. Both, [docker](https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e-env-env-file) and [docker-compose](https://docs.docker.com/compose/env-file/) support reading environment variables from a file.



The update scripts are intended to be used during manual deployments and expect stdin being available for prompting for your input.



## Docker



> You can also load the environment variables from a file.

> This file should use the syntax `=value` (which

> sets the variable to the given value) or ``

> (which takes the value from the local environment),

> and `#` for comments.



Note: Only the `=value` syntax, blank lines and comments are supported by this collection of scripts (i.e. not ``). Please feel free submitting merge requests to overcome this shortcoming.



## Docker-compose



> Compose supports declaring default environment variables

> in an environment file named `.env` placed in the folder

> where the `docker-compose` command is executed (*current

> working directory*).



> These syntax rules apply to the .env file:

>

> - Compose expects each line in an `env` file to be in `VAR=VAL` format.

> - Lines beginning with `#` (i.e. comments) are ignored.

> - Blank lines are ignored.

> - There is no special handling of quotation marks (i.e. **they will be part of the VAL**, you have been warned ;) ).



## Contents



- Limitations:

    - Install script will attempt attaching post-checkout hook to /dev/tty (Keyboard). This might break automated deployments. Do not use the script installer if your terminal is incompatible or if no keyboard device exists.

    - Might not handle literal `\n` in comments correctly. Please submit merge requests.

- Requirements: Bash version 4 support or higher



### update-env.sh



- Updates an existing `.env` file with missing variables from a template file by prompting for their value (offering a default from the template).

- Tracks who made the additions and when the additions were made.

- Prints possibly unused/obsolete variables to stdout.



### prettify-env.sh



- Re-creates an existing `.env` file using a templates fills missing variables by prompting for their value (offering a default from the template)

- Adds possibly unused/obsolete variables in a bottom section.

- Because the whole file is rewritten each time, the template structure is restored. With `diff .env.example .env` changes to the default values from the template are easily spotted.



## Git: Self-update when checking out another version



### Using an installation script

```sh

wget -qO- https://raw.githubusercontent.com/Rillke/Docker-env-file-update/master/install.sh | bash

```



### Step by step



Git provides so-called hooks. The `post-checkout` hook script is executed by Git after a new version is checked out (e.g. after a `git pull` or a `git checkout hash/tag/version`). This allows for keeping your `.env` file automatically up-to-date. Note that hooks are a local concept and do not become part of the repository, so install them in each clone of your repo you need them on.



Example:



0. Assuming that your template file's name is `.env.example` and your env file's name is `.env`.

1. In your repository create a `.git/hooks/post-checkout` file with the follwing contents:



```sh

#!/bin/sh

#

# After you run a successful git checkout, the post-checkout hook runs;

# you can use it to set up your working directory properly for your

# project environment. This may mean moving in large binary files that

# you don’t want source controlled, auto-generating documentation, or

# something along those lines.



if [ -f prettify-env.sh ]; then

  bash prettify-env.sh .env.example .env

else

  echo "prettify-env.sh not found. Your .env file won't be updated."

fi

```



2. Put a copy of `prettify-env.sh` into your repository (example is for the working directory but it should also work in the hidden `.git` directory if you adjust the paths in `.git/hooks/post-checkout` accordingly).

3. Test, however note that `prettify-env.sh` will remove all customized comments from `.env`. If you do not wish this behaviour, use `update-env.sh` instead. For instance, try `git checkout master`



### Uninstallation



Remove the line invoking the script from `post-checkout`, or if this is the only command invoked, delete the `post-checkout` file entirely. By default, you can find the `post-checkout` hook file under `.git/hooks`. If the file does not exist, run the installation script again (abort it with `Ctrl`+`C` if necessary) and it will tell you where your `post-checkout` hook file is located.



## Snippets



### Convert Docker `.env` file to bash-compatible `.env` file format



```sh

# Load environment

eval $( cat .env | grep -v ^# | sed -r 's/(["\\])/\\\1/g' | sed -rn 's/([^\=]+)\=(.+)/\1="\2"/p' )

# Store into file

cat .env | grep -v ^# | sed -r 's/(["\\])/\\\1/g' | sed -rn 's/([^\=]+)\=(.+)/\1="\2"/p' > .bash.env

```



1. Read `.env` file

2. Strip comments

3. Escape double quotes (`"`) and backslashes (`\`)

4. Enclose values in double quotes