Rough upgrade plan

[ErisDS]

Need to put together a rough plan of what upgrading Ghost is going to look like in the future.

How will database migrations work - how can we know what version a particular database is?
How can we make Ghost aware of what version it is?
How do we protect the database from being overridden?
How do we protect files in the custom content folder?

For now this is probably just a discussion that will result in some documentation & issues for implementing proper database migration etc.

[tgriesser]

I've got a basic migrations branch implementation here... still needs a bit of work, but ultimately I'm trying to make it in Knex so someone can call the migrations programmatically and have the migration state based off of a ghost_migrations table (or something like that) in the db...

[jgable]

How can we make Ghost aware of what version it is?

I think I introduced the version as a setting in #163.

[ErisDS]

For now, upgrades will require:

• backup your data using the export tool
• overwrite Ghost with latest files
  • should not overwrite the DB as there is no replacement DB file, I'm pretty sure that's true on all OS's but should double check
  • should not overwrite any /content files as there will be no replacements - again I should check, but perhaps upgrades should explicitly only replace core?
  • if you make changes directly to Casper it is to be expected that those be overwritten as you should create your own theme
• if anything goes wrong, re-import your data.

I think this is reasonably sound, and given we're only at 0.2.0, not even an alpha really, people should expect things to go wrong & that the upgrade process might be painful for a while.

Given that there is no code for this, I'm going to move this issue out of 0.1.1 but not close it as it may warrant further discussion.

[JohnONolan]

Let's flag heavily on vip.tg docs that developers may lose all data when upgrading Ghost

[ErisDS]

We have basic import and export features, and the ability to redeploy a Ghost instance reasonably easily as the deploy script works over and over.

There have been many breaking changes over the past 2-3 weeks, so I have written rough instruction on how to do an upgrade without losing data. It does require a bit of manual labour, but should work. Warning, I've not actually tested this yet! https://github.com/TryGhost/Ghost/wiki/Updating-Deployed-Ghost-Instances