Split single top-level status check into one plan and one apply check.
These checks will also now track the whole pull request status rather
than just the last action.
Automerging merges pull requests automatically if all plans have been
successfully applied.
* Save status of PR's to BoltDB so after each apply, we can check if
there are pending plans.
* Add new feature where we delete successful plans *unless* all plans
have succeeded *if* automerge is enabled. This was requested by users
because when automerge is enabled, they want to enforce that a pull
request's changes have been fully applied. They asked that plans not be
allowed to be applied "piecemeal" and instead, all plans must be
generated successfully prior to allowing any plans to be applied.
- Use logger for all warnings. Previously we were writing warnings from
cmd/server.go directly to stderr which bypassed our normal log format.
- Add the timezone to log output. This is just really nice to have if
you're looking at old logs.
- Change levels to all be 4 characters: DBUG, INFO, WARN, EROR. This
makes the logs easier to read because it lines up.
- Log when we first receive the request as well as when we send a
response. This makes it easier to see where the request starts and ends.
Previously, we were just logging when an error happened early in our
comment processing code. However it's possible for us to write comments
on error even at this early stage which will make for a better user
experience.
Fixes#398
