Ansible able to migrate database on upgrade

[thatarchguy]

A few issues in one here:

Ansible is able to perform database migrations on upgrade - #125
We now track migrations in the repository - #129

A special command was created for users that already have the virtual_* tables in their database. (People who already installed a mailserver prior to PostMaster)
python manage.py existingdb

[thatarchguy]

I had a merge conflict with the config.py file that turned in to a 3 way merge conflict that turned into the whole thing replaying its commits on top of itself. Sorry about that...

[mprahl]

@thatarchguy, is there any reason you don't have the --upgrade flag on here, but you do in ansible_install.sh? Maybe we can ensure that a minimum version is installed (i.e. 2.0+)

[thatarchguy]

I overlooked that. I have the --upgrade ansible setuptools in the install.sh script because ansible throws errors if you don't pip install setuptools after you install it from apt. It's weird I know.
And yeah we want ansible to be 2.0+ for sure.

[mprahl]

@thatarchguy,
The problem I see now is that the database migrations would potentially not be handled properly in Docker based on the state of the MySQL database. When you first deploy PostMaster via Docker, you might need to run python manage.py existingdb or python manage.py createdb depending on if you followed the mail server setup guide or not.

Maybe we should just have one command that has the logic to determine what state it's in. For instance, if the alembic table does not exist and virtual_* do, you know you need to run flask_migrate.stamp(revision='bcc85aaa7896'), otherwise, you would leave that out.

[thatarchguy]

Yeah I looked into this a lot and I couldn't figure out how to test if the tables existed or not in alembic. There were a few issues on stackoverflow and mailing lists with people in similar situations as ours. This two command thing was a compromise

[mprahl]

@thatarchguy, I don't think you need to read the data in the alembic table. You just need to something like:

if not alembic_table_exists and virtual_domains_exists and virtual_users_exists and virtual_aliases_exists:
    flask_migrate.stamp(revision='bcc85aaa7896')

flask_migrate.upgrade()
add_default_configuration_settings()

Edit:
You can check if the table exists with this code:

db.engine.dialect.has_table(db.session.connection(), 'virtual_users')

[mprahl]

@thatarchguy really nice job on this. I think my last commit addresses our issues. I'm ready to merge this if you are.

[thatarchguy]

Lgtm! Merge at will

[mprahl]