Merge pull request #52 from peopledoc/improve-quickstart

Improving the quick start documentation

README.rst

@@ -45,16 +45,24 @@ Septentrion supports PostgreSQL 9.6+ and Python 3.6+.
 .. _South: https://bitbucket.org/andrewgodwin/south/src
 .. _django-north: https://github.com/peopledoc/django-north
 
-Overview
---------
+Very quick start
+----------------
 
-- *Step 1*: Write your PostgreSQL migrations, name files and folders according to
-  a convention.
-- *Step 2*:
+- *Step 1*: Create a folder for the version, and add some migration files.
 
 .. code-block:: console
 
-    $ septentrion migrate
+    migrations/
+    └──  1.0
+        ├── 1.0-0-version-dml.sql
+        ├── 1.0-author-1-ddl.sql
+        └──  1.0-author-2-dml.sql
+
+- *Step 2*: Run septentrion
+
+.. code-block:: console
+
+    $ septentrion --target-version 1.0 migrate
 
 - *Step 3*: That's it.
 
@@ -71,8 +79,11 @@ Where to go from here
 
 The complete docs_ is probably the best place to learn about the project.
 
+You can check the quickstart_ guide to start running your first migrations.
+
 If you encounter a bug, or want to get in touch, you're always welcome to open a
 ticket_.
 
 .. _docs: http://septentrion.readthedocs.io/en/latest
+.. _quickstart: http://septentrion.readthedocs.io/en/latest/quickstart.html
 .. _ticket: https://github.com/peopledoc/septentrion/issues/new

docs/howto/advanced-options.rst

@@ -0,0 +1 @@
+# TODO This file will list advanced options for septentrion usage (eg using flags or env variables instead of a .ini file)

docs/howto/configure.rst

@@ -0,0 +1,12 @@
+Configure database connection settings
+--------------------------------------
+
+# TODO expand documentation on database connection
+
+Ensure that your database connection settings are correctly configured.
+
+ - Either your environment variables `PGHOST`, `PGPORT` and `PGUSER` are properly set.
+ - Or you can set the environment variables `SEPTENTRION_HOST`, `SEPTENTRION_PORT`, `SEPTENTRION_USERNAME`.
+ - configuration file `septentrion.ini`
+ - If you don't want to use environment variables, you can use the `--host`, `--port` or `--username` options
+   when running the migration.

docs/howto/file_naming.rst

@@ -0,0 +1,19 @@
+File naming convention
+----------------------
+
+# TODO explain the file naming convention
+# The following extract was inspired by the DBA documentation.
+
+We recommend to use the following naming convention for migration files:
+
+.. code-block:: console
+
+    [VERSION]-[MIGRATION]-[ORDER]-[TYPE].sql
+
+ - version : the release version
+
+ - migration : a free name for the migration
+
+ - order : a number used to order the files inside the migration
+
+ - type : ddl or dml, ddl if the file contains schema migration, dml if the file contains data migration.

docs/howto/troubleshoot.rst

@@ -0,0 +1 @@
+# TODO This file will contain help with the most common issues.

docs/quickstart.rst

@@ -1,10 +1,242 @@
 Quickstart
 ==========
 
+Welcome to the *Septentrion* quickstart documentation.
+
+In this tutorial, you will learn how to write migrations in the expected format, how to visualize them and how to run
+them against a PostgreSQL database.
+
+Prepare your database
+---------------------
+
+If you already have a PostgreSQL database around, make sure to note the connection
+parameters. Otherwise, we'll create one together with Docker_:
+
+.. _Docker: https://docs.docker.com/
+
+.. code-block:: console
+
+    $ docker run --detach --rm -p 5432:5432 --name septentrion_db postgres
+
+.. note::
+
+    If you need to stop the docker at some point, use ``docker stop septentrion_db``.
+
+.. note::
+
+    If you stop the Docker or reboot your machine, the Postgres database will be trashed and you will need to re-create
+    one and add some data again.
+
+
+You'll also need ``psycopg2``, which is notoriously complex to install. Septentrion
+will install the ``psycopg2`` python package, but will expect the system to already
+have the prerequisites (on ``Ubuntu``)::
+
+    $ sudo apt install libpq-dev python-dev postgresql-client
+
+.. note::
+    On a different OS, if you experiment difficulties, we'll be grateful if you can tell
+    us via an issue so that we improve this documentation.
+
+Install and configure Septentrion
+---------------------------------
+
+Within a virtualenv_, install Septentrion with:
+
+.. _virtualenv: https://packaging.python.org/tutorials/installing-packages/#creating-virtual-environments
+
+.. code-block:: console
+
+    (venv) $ pip install septentrion
+
+Next we will configure the connection to the PostgreSQL database. We can do this either with command line flags,
+environment variables or a configuration file.
+In this tutorial, we will use a configuration file, ``septentrion.ini``.
+
+.. code-block:: ini
+
+    [septentrion]
+    migrations_root=migrations
+    host=localhost
+    username=postgres
+    # port=5432
+
+.. note::
+
+    With the Docker setup described above, you should be good to go.
+    If you need additional configuration parameters to connect to your database, have a look at
+    :ref:`advanced configuration options <howto/configure>`.
+
+
+Write migrations
+----------------
+
+Migrations are SQL files that are executed in order. Migrations are grouped together in successive versions.
+All migrations in the same version are placed in a folder named after the version number.
+
+Let's create our migration folder, and a first version folder.
+
+.. code-block:: console
+
+    $ mkdir migrations
+    $ mkdir migrations/1.0
+
+Now we can add a migration file in ``migrations/1.0/`` named ``00-author.ddl.sql``:
+
+.. code-block:: sql
+
+    BEGIN;
+    CREATE TABLE "author" (
+        "id" serial NOT NULL PRIMARY KEY,
+        "name" varchar(100) NOT NULL,
+        "birth_date" varchar(10) NOT NULL
+    );
+    COMMIT;
+
+.. note::
+
+    Migrations are executed in alphabetical order, so an easy way to control the order is to prefix filenames with two
+    digits.
+
+.. note::
+
+    ``ddl`` stands for *Data Definition Language* and corresponds to all the operations that change the structure of the
+    database (``CREATE``, ``DROP``, ...).
+
+Congratulations, you have now written your first *Septentrion* migration. Let's see how to run it!
+
+
+Run migrations
+--------------
+
+First, we want to visualize what is going to happen, without making any change to our data yet.
+
+.. code-block:: console
+
+    $ septentrion --target-version 1.0 show-migrations
+
+    Current version is None
+    Target version is 1.0
+    Version 1.0
+      [ ] 00-author.ddl.sql
+
+
+
+Great, we can now run it for real:
+
+.. code-block:: console
+
+    $ septentrion --target-version 1.0 migrate
+
+    Applying migrations
+    Version 1.0
+
+
+
+.. note::
+
+    You should run *septentrion* in your root directory, where your ``migrations`` folder is.
+
+.. note::
+
+    The ``--target-version`` flag is a required option (it might change in the future).
+
+
+If something is not working as it should be, you probably want to check the :ref:`troubleshooting guide <howto/troubleshoot>`
+or the :ref:`advanced options <howto/advanced-options>`.
+
+At this point, the ``author`` table has been created in the database. We can check that and simulate our application
+by creating a few rows in the table.
+
+
+.. code-block:: console
+
+    $ psql --host localhost --user postgres postgres
+
+    postgres=# \d
+
+                          List of relations
+     Schema |             Name              |   Type   |  Owner
+    --------+-------------------------------+----------+----------
+     public | author                        | table    | postgres
+     public | author_id_seq                 | sequence | postgres
+     public | septentrion_migrations        | table    | postgres
+     public | septentrion_migrations_id_seq | sequence | postgres
+     public | sql_version                   | table    | postgres
+    (5 rows)
+
+    postgres=# INSERT INTO author (name, birth_date)
+    VALUES
+    ('Victor Hugo', '1802-02-26'),
+    ('George Gordon Byron', '1788-01-22'),
+    ('JRR Tolkien', '1892-01-03');
+    INSERT 0 3
+
+    postgres=# SELECT * FROM author;
+     id |        name         | birth_date
+    ----+---------------------+---------------
+      0 | Victor Hugo         | 1802-02-26
+      1 | George Gordon Byron | 1788-01-22
+      2 | JRR Tolkien         | 1892-01-03
+    (3 rows)
+
+
+
+A more complex migration
+------------------------
+
+For version ``2.0`` of our application, we want to change ``birth_date`` from ``varchar`` to the ``date`` type.
+
+We create a new folder for the version.
+
+.. code-block:: console
+
+    $ mkdir migrations/2.0
+
+We can add the migration file in ``migrations/2.0/`` named ``00-change_birth_date_type.ddl.sql``:
+
+.. code-block:: sql
+
+    BEGIN;
+    ALTER TABLE author
+        ALTER COLUMN birth_date
+        TYPE DATE USING to_date(birth_date, 'YYYY-MM-DD');
+    COMMIT;
+
+
+We launch the migration.
+
+.. code-block:: console
+
+    $ septentrion --target-version 2.0 migrate
+
+    Applying migrations
+    Version 1.0
+      [X] Already applied
+    Version 2.0
+      [X] Applied 00-change_birth_date_type.ddl.sql
+
+Now we can check that our migration successfully changed the column type in the ``author`` table.
+
+.. code-block:: console
+
+    $ psql --host localhost --user postgres postgres
+    postgres=# SELECT column_name, data_type FROM information_schema.columns WHERE table_name = 'author';
+      column_name  |     data_type
+    ---------------+-------------------
+     id            | integer
+     name          | character varying
+     date_of_birth | date
+    (3 rows)
+
+
+
+Congratulations, you can now run migrations with *Septentrion*!
+
 Going further
 -------------
 
-To continue with practical steps, head to the :ref:`How-to... <how-to>` section.
+To continue with practical steps, head to the :ref:`How-to... <howto>` section.
 
 If you want to better understand some design decisions, head to the :ref:`Discussions
 <discussions>` sections.