# 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, "~> 2.1.0"}]
end
```
### Configuration
```elixir
config :weave,
file_directory: "path/to/secrets", # Only needed when using the File loader
environment_prefix: "MYAPP_", # Only needed when using the Environment loader
handler: Your.Handler, # Always needed :smile:
loaders: [
Weave.Loaders.File,
Weave.Loaders.Environment
]
```
### Manual Handler
Your handler is responsible for taking these environment variables, and/or files, and injecting their values into configuration.
`handle_configuration/2` should return a tuple with the `:app` to set the key value pair on.
Weave will handle merging, so try not to worry about that :smile:
#### 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 Your.Handler do
def handle_configuration("name", value) do
{:app, :name, value}
end
def handle_configuration("db_password", value) do
{:app, :password, value}
end
# Sometimes you need to use the same value twice, so return a list.
# NB: We *may* make returning lists the default in the future.
def handle_configuration("kafka_host", host) do
[
{:kaffe, :consumer, [host: {String.to_atom(host): 9092}]},
{:kaffe, :producer, [host: {String.to_atom(host): 9092}]}
]
end
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}
```
NB: For now, `config :weave, handler: BLAH` is still required, even if no `handle_configuration/2` functions.
### Loading Configuration
You'll need to add the following to your `start` function, before you prepare your supervisor:
```elixir
Weave.configure()
```
If you really wish, you can omit `:loaders` during configuration and load from it manually:
```elixir
Weave.Loaders.Environment.load_configuration()
Weave.Loaders.File.load_configuration()
```
### Logging
Weave **may** log sensitive information at the `debug` level, stick to `info` in production.
### Contributing
#### Running Tests with Docker
```shell
$ docker-compose run --rm elixir
```
