env2ini

Creates and updates INI files from environment variables.

Installation

Install with go:

go get github.com/nextrevision/env2ini

With curl using a specific release:

curl -L -o env2ini \
  https://github.com/nextrevision/env2ini/releases/download/0.2.0/env2ini_linux_amd64
chmod +x env2ini

Usage

Usage of env2ini:
  -debug
        enable debug logging
  -filename string
        destination filename for writing settings (required)
  -prefix string
        environment prefix to look for keys (required)

To configure the file /etc/config.ini with environment variables starting with MYAPP, you would run:

$ export MYAPP__DEFAULT__conn="mysql://user:pass@mysql/myapp"
$ export MYAPP__section1__key1=myapp_value1

$ ./env2ini -filename /etc/config.ini -prefix MYAPP
INFO[0000] Updated setting                               key=conn section=DEFAULT
INFO[0000] Updated setting                               key=key1 section=section1

Which would result in /etc/config.ini looking like:

conn = mysql://user:pass@mysql/myapp

[section1]
key1 = myapp_value1

Key Syntax

For a key to be added into an INI configuration, the following must be true:

• The variable matches the following syntax: PREFIX__SECTION__KEY=value
• There is a support for the config file listed in the table below

The double underscore (__) serves as a delimiter for the prefix, section, and key. Each of those components can contain underscores themselves, just not two consecutive.

Examples

Simple

To update a the key connection in section database to the value mysql://user:pass@host:3306/db in file /etc/config.ini, a variable would be exported in the environment as:

MYAPP__database__connection=mysql://user:pass@host:3306/db

After running env2ini, we could expect the following in /etc/config.ini:

[database]
connection = mysql://user:pass@host:3306/db

Complex Section/Key Names

To update a section or key with a colon, period (dot), or forward slash, we can make use of a few reserved words: COLON, DOT, and SLASH. If we wanted to reverse engineer the following output in /etc/config.ini:

[composite:main]
use = egg:Paste#urlmap
/v2.0 = public_api
/v3 = api_v3
/ = public_version_api

We can use the following exported variables:

MYAPP__COMPOSITE_COLON_MAIN__USE='egg:Paste#urlmap'
MYAPP__COMPOSITE_COLON_MAIN__SLASH_V2_DOT_0='public_api'
MYAPP__COMPOSITE_COLON_MAIN__SLASH_V3='api_v3'
MYAPP__COMPOSITE_COLON_MAIN__SLASH='public_version_api'