add README file (#8)

README.md

@@ -1,2 +1,152 @@
 # atlas-provider-doctrine
-Atlas provider for PHP doctrine
+
+Load [Doctrine](https://www.doctrine-project.org/) entities into an [Atlas](https://atlasgo.io) project.
+
+### Use-cases
+1. **Declarative migrations** - use a Terraform-like `atlas schema apply --env doctrine` to apply your Doctrine schema to the database.
+2. **Automatic migration planning** - use `atlas migrate diff --env doctrine` to automatically plan a migration from the current database version to the Doctrine schema.
+
+### Installation
+
+Install Atlas from macOS or Linux by running:
+```bash
+curl -sSf https://atlasgo.sh | sh
+```
+
+See [atlasgo.io](https://atlasgo.io/getting-started#installation) for more installation options.
+
+Install the provider by running:
+```bash
+composer require ariga/atlas-provider-doctrine
+```
+
+#### Doctrine Console Command
+
+If all of your Doctrine entities exist under single directory,
+you can add the atlas-provider command to the Doctrine Console file:
+
+```diff
+#!/usr/bin/env php
+<?php
+
+use Doctrine\ORM\Tools\Console\ConsoleRunner;
+use Doctrine\ORM\Tools\Console\EntityManagerProvider\SingleManagerProvider;
+
+require 'bootstrap.php';
++ require "vendor/ariga/atlas-provider-doctrine/src/Command.php";
+
+ConsoleRunner::run(
+    new SingleManagerProvider($entityManager),
++   [new AtlasCommand()]
+);
+```
+
+Then in your project directory, create a new file named `atlas.hcl` with the following contents:
+
+```hcl
+data "external_schema" "doctrine" {
+  program = [
+    "php",
+    "bin/doctrine", // path to your Doctrine Console file
+    "atlas:dump-sql",
+    "--path", "./path/to/entities",
+    "--dialect", "mysql" // mariadb | postgres | sqlite | sqlserver
+  ]
+}
+
+env "doctrine" {
+  src = data.external_schema.doctrine.url
+  dev = "docker://mysql/8/dev"
+  migration {
+    dir = "file://migrations"
+  }
+  format {
+    migrate {
+      diff = "{{ sql . \"  \" }}"
+    }
+  }
+}
+```
+
+#### As PHP Script
+
+If you have multiple folders with Doctrine entities, you might want to use the provider as a php script.
+
+create a new file named `atlas.php` with the following contents:
+
+```php
+<?php
+
+require "vendor/autoload.php";
+require "vendor/ariga/atlas-provider-doctrine/src/LoadEntities.php";
+
+print (DumpDDL(["./path/to/first/entities", "./path/to/more/entities"], "mysql"));
+```
+
+Then in your project directory, create a new file named `atlas.hcl` with the following contents:
+
+```hcl
+data "external_schema" "doctrine" {
+  program = [
+    "php",
+    "atlas.php"
+  ]
+}
+
+env "doctrine" {
+  src = data.external_schema.doctrine.url
+  dev = "docker://mysql/8/dev"
+  migration {
+    dir = "file://migrations"
+  }
+  format {
+    migrate {
+      diff = "{{ sql . \"  \" }}"
+    }
+  }
+}
+```
+
+### Usage
+
+Once you have the provider installed, you can use it to apply your Doctrine schema to the database:
+
+#### Apply
+
+You can use the `atlas schema apply` command to plan and apply a migration of your database to your current Doctrine schema.
+This works by inspecting the target database and comparing it to the Doctrine schema and creating a migration plan.
+Atlas will prompt you to confirm the migration plan before applying it to the database.
+
+```bash
+atlas schema apply --env doctrine -u "mysql://root:password@localhost:3306/mydb"
+```
+Where the `-u` flag accepts the [URL](https://atlasgo.io/concepts/url) to the
+target database.
+
+#### Diff
+
+Atlas supports a [version migration](https://atlasgo.io/concepts/declarative-vs-versioned#versioned-migrations)
+workflow, where each change to the database is versioned and recorded in a migration file. You can use the
+`atlas migrate diff` command to automatically generate a migration file that will migrate the database
+from its latest revision to the current Doctrine schema.
+
+```bash
+atlas migrate diff --env doctrine 
+````
+
+### Supported Databases
+
+The provider supports the following databases:
+* MySQL
+* MariaDB
+* PostgreSQL
+* SQLite
+* Microsoft SQL Server
+
+### Issues
+
+Please report any issues or feature requests in the [ariga/atlas](https://github.com/ariga/atlas/issues) repository.
+
+### License
+
+This project is licensed under the [Apache License 2.0](LICENSE).