We want to show any helpful performance data in the GoodJob demo app so
we are installing PGHero:

https://github.com/ankane/pghero

We have to add Sprockets to the Rails app so the PGHero assets get loaded
correctly, whilst we could have used a more modern asset pipeline,
Sprockets is well supported and a simple drop in to get PGHero running.

PGHero is available at `/pghero`.

We have not enabled:

- [Suggested indexes](https://github.com/ankane/pghero/blob/master/guides/Rails.md#suggested-indexes)
- [Historical query stats](https://github.com/ankane/pghero/blob/master/guides/Rails.md#query-stats)
- [Historical space stats](https://github.com/ankane/pghero/blob/master/guides/Rails.md#historical-space-stats)

As these may not be suitable for the demo application and can always be
added later.

We want to be sure PgHero is behind basic auth. This spec validates that
once the correct environment variables are set, PgHero will require
basic authentication.

We have to use the rack_test driver so we can use `basic_authorize` to
set the headers, rack_test is the default in RSpec/Capybara, but we have
explicitly set the driver just in case.

This does the work to enable historical query stats in PgHero, but the
Postgres instance backing the service must also be configured, see:

https://github.com/ankane/pghero/blob/master/guides/Rails.md#query-stats

We are:

- adding the tables to store stats
- setting up a GoodJob cron job to collect the stats and clean old ones
(the demo app generates a lot of queries)

For reference, the recommended settings for `postgres.conf`:

```
shared_preload_libraries = 'pg_stat_statements'
pg_stat_statements.track = all
pg_stat_statements.max = 10000
track_activity_query_size = 2048
```

See:

https://github.com/ankane/pghero/blob/master/guides/Query-Stats.md