Movine

Movine is a simple database migration manager that aims to be compatible with real-world migration work. Many migration managers get confused with complicated development strategies for the migrations. Movine attempts to solve this issue by keeping track of the unique hashes for the up.sql and down.sql for each migration. This allows users to easily keep track of whether their local migration history matches the one on the database.

This project is currently in very early stages, and should be considered a proof-of-concept. The base functionality is implemented, but things should be expected to change.

Movine does not aim to be an ORM. Consider diesel instead if you want an ORM.

Migration Concepts

Movine keeps track of four different states of migrations on the database. There are the basic ones:

Applied: Found locally and applied to the database
Pending: Found locally and not applied to the database

Then there are the more complicated ones, which Movine was specifically designed to handle:

Variant: Found locally but a different version is applied to the database
Divergent: Not found locally but applied to the database

Getting Started

The first step to get started with Movine is to set the configuration. Configuration can be supplied either through a movile.toml file or environment variables:

movine.toml

This file stores the connection parameters that Movine needs in order to connect to the database. In the future this file will also hold various parameters to customize the way Movine operates.
```
[postgres]
host = {host}
database = {db}
user = {username}
password = {pass}
port = {port}

## Or use the Sqlite adaptor
[sqlite]
file={file}
```
Environment variables

You can configure the PostgreSQL adaptor using the environment variables described in the PostgreSQL documentation; namely PGHOST, PGPORT, PGDATABASE, PGUSER, and PGPASSWORD. All are currently required.

You can configure the SQLite adaptor using an SQLITE_FILE environment variable.

Movine supports .env files as a source of configuration.

Next, you can run the init command to set everything up, the generate command to create your first migration, and once those are written you can run up to apply them.

$ movine init
$ tree migrations/
migrations/
└── 1970-01-01-000000_movine_init
    ├── down.sql
    └── up.sql

1 directory, 2 files
$ movine generate create_new_table
$ tree migrations/
migrations/
├── 1970-01-01-000000_movine_init
│   ├── down.sql
│   └── up.sql
└── 2019-03-17-163451_create_new_table
    ├── down.sql
    └── up.sql

2 directories, 4 files
$ movine up
$ movine status
2019-03-17 16:34:51 UTC - Applied   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Commands

There are a few commands that Movine uses, and all of them can be listed by using --help on the command line.

Init

The init command will run the initialization routine for Movine, which will create a table on the database to keep track of migrations and create a local migrations folder.

$ movine init
$ ls
migrations/   movine.toml
$ tree migrations/
migrations/
└── 1970-01-01-000000_movine_init
    ├── down.sql
    └── up.sql

1 directory, 2 files
$ psql $PARAMS -c "\d"
                   List of relations
 Schema |           Name           |   Type   | Owner
--------+--------------------------+----------+--------
 public | movine_migrations        | table    | movine
 public | movine_migrations_id_seq | sequence | movine

Generate

The generate command will generate a folder with the current date and the given name in the migrations/ directory with blank up.sql and down.sql files.

$ movine generate create_new_table
$ tree migrations/
migrations/
├── 1970-01-01-000000_movine_init
│   ├── down.sql
│   └── up.sql
└── 2019-03-17-163451_create_new_table
    ├── down.sql
    └── up.sql

2 directories, 4 files

Status

The status command will tell you the current state of all migrations, both local and on the database.

$ movine status
2019-03-17 16:34:51 UTC - Pending   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Up

The up command will run all pending migrations. You can also run with the -p flag to show the migration plan without running it. This is true for all commands that modify the database and is useful for seeing if Movine will do what you expect.

$ movine up -p
1. Up   - 2019-03-17-163451_create_new_table
$ movine status
2019-03-17 16:34:51 UTC - Pending   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init
$ movine up
$ movine status
2019-03-17 16:34:51 UTC - Applied   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Down

The down command will rollback the most recent migration.

$ movine down
$ movine status
2019-03-17 16:34:51 UTC - Pending   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Redo

The redo command will rollback and then re-apply the most recent applied migration or variant migration. Note: If the latest migration is divergent then redo will simply skip it. Be careful, and run fix if you want to fix divergent migrations.

$ movine status
2019-03-17 16:34:51 UTC - Variant   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init
$ movine redo
$ movine status
2019-03-17 16:34:51 UTC - Applied   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Fix

The fix command will rollback everything until there are no divergent or variant migrations, and then apply all migrations except the migrations that were pending at the start.

$ movine status
2019-03-17 16:41:07 UTC - Pending   2019-03-17-164107_create_another_table
2019-03-17 16:40:59 UTC - Divergent 2019-03-17-164059_modify_table
2019-03-17 16:34:51 UTC - Variant   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init
$ movine fix
$ movine status
2019-03-17 16:41:07 UTC - Pending   2019-03-17-164107_create_another_table
2019-03-17 16:34:51 UTC - Applied   2019-03-17-163451_create_new_table
1970-01-01 00:00:00 UTC - Applied   1970-01-01-000000_movine_init

Custom

The custom command will allow you to specify your own migration strategy (in case Movine is not smart enough). Note: this is currently not implemented

Library Usage

Note: this API is in flux

Movine can be used as a library like so:

use movine::{Movine, Config};
use movine::errors::Error;

fn main() -> Result<(), Error> {
    let config = Config::from_file("movine.toml")?;
    let adaptor = config.into_sqlite_adaptor()?;
    let mut movine = Movine::new(adaptor);
    movine.fix()?;
    Ok(())
}

Or, if you want to provide the params without going through the config file:

use movine::{Movine, Config};
use movine::adaptor::SqliteAdaptor;
use movine::errors::Error;

fn main() -> Result<(), Error> {
    let adaptor = SqliteAdaptor::new("file.db")?;
    let mut movine = Movine::new(adaptor);
    movine.fix()?;
    Ok(())
}

Why you should use Movine

You are tolerant to occasional breakage
You want to write raw sql for your migrations
You have a shared database that has migrations developed by multiple developers
You are bad at rolling back a migration before editing it

Why you should not use Movine

You want a robust and proven database migration manager
You want ORM integration (consider the diesel instead)
You don't see value in keeping track of variant or divergent migrations.

movine 0.4.4