Database Lab access using the `pgai` Ruby gem - Gitlabhq

@mbobin created the pgai Ruby Gem that greatly simplifies access to a database clone, with support for:

Access to all database clones listed in the Postgres.ai instances page;
Multiple psql sessions on the same clone.

If you have AllFeaturesUser psql access, you can follow the steps below to configure the pgai Gem:

To get started, you need to gather some values from the Postgres.ai instances page:
1. Go to the instance that you want to configure and the on right side of the screen.
2. Under Connection, select Connect. The menu might be collapsed.
  
  A dialog with everything that's needed for configuration appears, using this format:
  shell
```
dblab init --url "http://127.0.0.1:<local-port>" --token TOKEN --environment-id <environment-id>
```
  shell
```
ssh -NTML <local-port>:localhost:<instance-port> <instance-host> -i ~/.ssh/id_rsa
```
To configure ssh, follow the instruction at Access the console with psql, replacing ${USER} with your postgres.ai username.

Run the following commands:

shell

gem install pgai

# Before running the following command,
# grab an access token from https://console.postgres.ai/gitlab/tokens
pgai config --prefix=<postgresai-user>

# Grab the respective port values from https://console.postgres.ai/gitlab/instances
# for the instances you'll be using (in this case, for the `main` database instance)
pgai env add --alias main --id <instance-host> --port <instance-port> -n gitlabhq_dblab

Once this one-time configuration is done, you can use pgai connect to connect to a particular database. For instance, to connect to the main database:
shell
```
pgai connect main
```
Once done with the clone, you can destroy it:
shell
```
pgai destroy main
```