# Molasses
[](https://travis-ci.org/securingsincity/molasses)
[](https://coveralls.io/github/securingsincity/molasses?branch=master)
A feature toggle library using redis or SQL (using Ecto) as a backing service. It allows you to roll out to users based on a percentage. Alternatively, you can use Molasses to deploy to a group of users or user ids.
## Installation
1. Add `molasses` to your list of dependencies in `mix.exs` and run `mix deps.get`:
```elixir
def deps do
[{:molasses, "~> 0.2.0"}]
end
```
2. Install related dependencies by including `ExRedis`, `MongoDB` or `Ecto` and one of its adapter libraries for Postgres or Mysql.
2A. Redis
For Redis, you will just need to include `exredis`:
```elixir
def deps do
[
{:molasses, "~> 0.2.0"},
{:exredis, ">= 0.2.4"}
]
end
```
2B. SQL using Ecto
For Ecto with PostgreSQL, install `ecto` and `postgrex`. You will also need to start ecto and postgrex as applications:
```elixir
def deps do
[
{:molasses, "~> 0.2.0"},
{:ecto, "~> 2.1.1"},
{:postgrex, ">= 0.0.0"}
]
end
def application do
[applications: [:ecto, :postgrex]]
end
```
Your config will also need to change. You will need to set up an Ecto Repo like you would [here](https://hexdocs.pm/ecto/Ecto.html#module-repositories). As well as set the Molasses adapter to postgres.
```elixir
# molasses adapter setting
config :molasses, adapter: "ecto"
```
You will need to create an ecto migration and add the features tables.
```elixir
defmodule Repo.CreateTestMocks do
use Ecto.Migration
def change do
create table(:features) do
add :name, :string
add :percentage, :integer
add :users, :string
add :active, :boolean
end
create index(:features, [:name])
end
end
```
2C. MongoDB
```elixir
def deps do
[
{:molasses, "~> 0.2.0"},
{:mongodb, ">= 0.0.0"},
]
end
```
For a working example of how to set up Molasses look at [Molasses Example](https://github.com/securingsincity/molasses-example)
## Usage
Molasses uses the same interface whether you are using Redis or SQL. Each function takes an `Ecto.Repo` or the `ExRedis` client as the first argument.
### Activate
* `activate/2` - Activates a feature for all users.
* `activate/3` - Activates a feature for some users.
* When the last argument is an integer then it sets the feature active for a percentage of users.
* When the last argument is a string then it sets a feature active for that specific user or user group.
* When the last argument is a list then it sets a feature active for that specific list of users or user groups
### Deactivate
* `deactivate/2` - Dectivates a feature for all users.
### Checking to see if a feature is active
* `is_active/2` - Check to see if a feature is active for all users.
* `is_active/3` - Check to see if a feature is active for a specific user.
## Examples
### Redis
```elixir
# Create a new redis client
{:ok, client} = Exredis.start_link
# activate a feature
Molasses.activate(client, "my_feature")
# activate a feature for a percentage of users
Molasses.activate(client, "my_feature", 75)
# activate a feature for a subset of integer based userIds
Molasses.activate(client, "my_feature", [2, 4, 5])
# activate a feature for a subset of string based userIds (think a mongoId) or a list of groups
Molasses.activate(client, "my_feature", ["admins", "super admins"])
# activate a feature for only one group of users
Molasses.activate(client, "my_feature", "powerusers")
# checking if a feature is active for all users
Molasses.is_active(client, "my_feature")
# checking if a feature is active for a specific user (based on percentage, or user id/group)
Molasses.is_active(client, "my_feature", identifier)
# deactivate a feature
Molasses.deactivate(client, "my_feature")
```
### Ecto
```elixir
# Switched to ecto as my adapter
Application.put_env(:molasses,:adapter, "ecto")
# alias the Repo for use
alias Molasses.Test.Repo
# use is_active and activate the same way but it uses the Ecto repo instead of
Molasses.activate(Repo, "my_feature", 75)
Molasses.is_active(Repo, "my_feature")
```
### MongoDB
```elixir
# Switched to ecto as my adapter
Application.put_env(:molasses,:adapter, "mongo")
# Create a new mongo client
{:ok, conn} = Mongo.start_link(database: "molasses")
# use is_active and activate the same way but it uses the Ecto repo instead of
Molasses.activate(conn, "my_feature", 75)
Molasses.is_active(conn, "my_feature")
```
