# Weave
[](https://hex.pm/packages/weave)
[](https://hex.pm/packages/weave)
[](https://hex.pm/packages/weave)
[](https://travis-ci.org/GT8Online/weave)
[](https://codecov.io/gh/GT8Online/weave)
## A JIT configuration loader for Elixir
### About
This library makes it possible to load configuration, especially secrets, from disk (Ala Docker Swarm / Kubernetes) on start-up.
### Installation
```elixir
def deps do
[{:weave, "~> 3.1"}]
end
```
### Configuration
```elixir
config :weave,
file_directories: ["/path/to/secrets"], # Only needed when using the File loader
environment_prefix: "MYAPP_", # Only needed when using the Environment loader
loaders: [
Weave.Loaders.File,
Weave.Loaders.Environment
]
```
### :weave Module
In order to transform environment variables, or file contents, to runtime configuration, you must tell `:weave` how to handle those values.
You do this by creating a `:weave` module, such as:
```elixir
defmodule MyApp.Weave do
use Weave
weave "some_environment_var_without_the_prefix",
required: false, # required: can be omitted and defaults to false
hander: {:myapp, :some_key}, # handler: can be a function, list or tuple
hander: [{:myapp, :some_key}, {:myapp, :another_key}]
hander: fn(value) -> Logger.configure(value) end)
end
```
#### Example
Lets assume:
* We are using the environment and file loaders
* We have the `environment_prefix` configured as `MY_APP_`
* We have an environment variable called `MY_APP_NAME`
* We have a file in configured secrets directory called `db_password`
Before being passed to your handler:
* All file-names and environment variables are lower-cased
* Environment variables have the prefix stripped
```elixir
defmodule MyApp.Weave do
use Weave
weave "name", handler: {:app, :name}
weave "db_password", required: true, handler: {:app, :password}
# Sometimes you need to use the same value twice, so return a list.
weave "kafka_host", handler: [
{:kaffe, :consumer},
{:kaffe, :producer}
]
end
```
#### Auto Handler Example
##### Warning: We intially thought this would help you reduce all the boilerplate associated with writing handlers. We're now not sure this is really worth it. Use with caution.
In-order to cut down on the boilerplate, you can use the "handler-free" approach and ensure that the values of your environment variables, or contents of files, contain:
```elixir
{:auto, :app, :name, value}
```
### Loading Configuration
You'll need to add the following to your `configure` function, before you prepare your supervisor:
```elixir
MyApp.Weave.configure()
```
### Logging
Weave **may** log sensitive information at the `debug` level, stick to `info` in production.
#### Running Tests with Docker
```shell
$ make clean deps test
```
