Rake db：migrate刚刚还原（回滚）所有迁移

Question

I just merged a branch and ran rake db:migrate on staging and it reverted all my migrations. (instead of migrating the new one)

I then went back to master, reloaded the db and ran migrations and again, the db got wiped out as before.

Any tips on how to debug that?

Why would db:migrate even rollback any migrations?

Any tips on how to maybe use a different command which tells rails only to grab new migrations and do up and will never roll back any migrations?

Answer 1

If a VERSION environment variable is set then rails will migrate to that version rather than the latest. In particular since rails calls to_i it will migrate to version 0 if it contains a non integer value. You can check this by running env (to list all environment variables) or ( echo $VERSION )

This is largely a relic from when rake didn't support passing arguments to tasks on the command line so people use to emulate them with environment variables so that you could do

rake db:migrate VERSION=xyz