rambler

A simple and language-independent SQL schema migration tool

Installation

You can download the latest release on the release page of the project.

Go users can also simply compile it from source and install it as a go executable using the following command :

go install github.com/elwinar/rambler

Releases are compiled using the wonderful XGo. Don't hesitate to check it out, it really kicks some serious ass.

Usage

Migrations

In rambler, migrations are kept in the simplest form possible: a migration is a list of sections (up and down), each section being an SQL statement. Example:

-- rambler up

CREATE TABLE foo (
    id INTEGER UNSIGNED AUTO_INCREMENT,
    bar VARCHAR(60),
    PRIMARY KEY (id)
);

-- rambler down

DROP TABLE foo;

Sections are delimited by SQL comments sufixed by the rambler marker (white-spaces sensitive). While applying a migration, rambler will execute each up section in order, and while reversing it it will execute each down section in reverse order.

Migrations are executed in alphabetical order, thus a versionning scheme of the form version_description.sql is highly recommended, version being an integer value, and description an underscored string. Examples:

201409272258_Added_table_foo.sql
01_First_migration.sql

Configuration

Rambler configuration is lightweight: just dump the credentials of your database and the path to your migrations' directory into a JSON file, and you're done. Here is an example or JSON configuration file with the default values of rambler:

{
    "driver": "mysql",
    "protocol": "tcp",
    "host": "localhost",
    "port": 3306,
    "user": "root",
    "password": "",
    "database": "",
    "directory": "."
}

When running, rambler will try to find a configuration file in the working directory and use its values to connect to the managed database.

HJSON

Rambler now supports HJSON configuration files, which is by the way retrocompatible with JSON.

Drivers

Rambler supports actually 3 drivers:

mysql
postgresql
sqlite

Don't hesitate to get in touch if you want to see another one supported, provided a golang database/sql driver exist for your database vendor.

Applying a migration

To apply a migration, use the apply command.

rambler apply

Rambler will compare the migrations already applied and the available migrations in increasing order to find the next migration to apply, then execute all its up sections' statements in order.

Reversing a migration

To reverse a migration, use the reverse command.

rambler reverse

Rambler will compare the migrations already applied and the available migrations in decreasing order to find the last applied migrations, then execute all its down sections' statements in reverse order.

Options

You can tell rambler to repeat the process while there is a migration to apply (or reverse) with the all flag (or its shorthand, a).

Errors

To ensure database schema consistency, rambler will complain and stop when encountering a new migration in the middle of the already existing ones or if it can't find a migration already applied.

Environments

An environment is an additionnal configuration that is given a name, and can be used to create multiple configurations for a single application (for example, to differenciate production, testing, etc).

Environments are defined in the configuration file, under the environments item. Each environment is defined as an attribute of this item, the key being the name and the value being the configuration options.

Environments configuration are derived from the default configuration of rambler (at the configuration file's root), so you only need to override the needed options:

{
    "driver": "mysql",
    "protocol": "tcp",
    "port": 3306,
    "user": "root",
    "password": "",
    "database": "rambler_default",
    "directory": "migrations",
    "environments": {
        "development": {
            "database": "rambler_development"
        },
        "testing": {
            "database": "rambler_testing"
        }
    }
}

Here we have three environments defined:

default, will use the rambler_default database,
development, will use the rambler_development database,
testing, will use the rambler_testing database;

CONTRIBUTORS

Feedback and contributions

Feel free to give feedback, make pull requests or simply open issues if you find a bug or have an idea.