# StrongMigrations

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**Catch unsafe migrations in your Elixir application**

## Table of Contents
* [What is it?](#what-is-it)
* [How to install?](#how-to-install)
* [How to configure?](#how-to-configure)
* [Similar packages](#similar-packages)

## What is it
`strong_migrations` is a library that protects your application from invoking unsafe migrations, they needs to be marked as a safe.
1. Analyze migrations if they are safe.
2. If migrations are unsafe -> print errors.
3. If migrations are safe -> use `ecto.migrate`.

You can also use a macro of `StrongMigrations` like `safety_assured` to be sure it's safe and you can run migrations with specific changes. Example
```elixir
defmodule SafetyAssuredDropTable do
  @moduledoc false

  use StrongMigrations

  def change do
    safety_assured do
      drop(table(:users))
    end
  end
end
```

![](asset/img/example.png)

#### Features
- checking if your migrations are adding an index concurrently in transaction
- checking if your migrations are adding an index but not concurrently
- checking if your migrations are removing an index concurrently in transaction
- checking if your migrations are renaming columns (it's always better to remove old and add new column)
- checking if your migrations are removing columns
- checking if your migrations are removing tables
- mark `safety assured do: drop table(:posts)` or multiline when you're sure it's safe
... tbd

## How to install
The package can be installed by adding `strong_migrations` to your list of dependencies in `mix.exs` as follows. Also, it's worth adding an alias like: `ecto.migrate -> strong_migrations.migrate` and thanks to that you'll be sure that all migrations were checked before running.

Update your `mix.exs`:
```elixir
def deps do
  [
    {:strong_migrations, "~> 0.1"}
  ]
end
```

## How to configure
If you want to specify which classifiers you want to use, please add to your `config.exs` following lines
```elixir
config :strong_migrations,
  classifiers: [
    StrongMigrations.Classifiers.AddIndexConcurrentlyInTransaction,
    StrongMigrations.Classifiers.AddIndexNotConcurrently,
    StrongMigrations.Classifiers.DropIndexConcurrentlyInTransaction,
    StrongMigrations.Classifiers.DropTable,
    StrongMigrations.Classifiers.RemoveColumn,
    StrongMigrations.Classifiers.RenameColumn
  ]
```

If you want to specify migration paths available in your project (not default -> `priv/repo/migrations`), please add to your `config.exs` following lines
```elixir
config :strong_migrations,
  migration_paths: [
    "priv/repo/migrations",
    "apps/*/priv/repo/migrations",
    "my/fancy/path/to/migrations"
  ],
```

## Similar Packages
* http://github.com/ankane/strong_migrations (Ruby)