Allow for configuration of redis connection via URL

[lukemelia]

We should be able to provide a URL in configuration connection to redis. It is supported by then-redis, so it shouldn't be too much work to support it in this library. Developers commonly have connection info available as a URL (from an env var, for example), and they shouldn't have to write code to parse it out.

[LevelbossMike]

This is actually already supported but not documented. You just have to pass the url as a string instead of a configuration object to the store property of the respective environment.

[jamesdixon]

Just to confirm, you pass the connection string directly to store? Also, what is the format of the connection string that's accepted? I've tried a few different versions with no success. Thank you!

[backspace]

I tried this: production: {store: 'redis://…'} and it worked, though it produced this error:

Unhandled rejection Error: ERR invalid DB index

[lukemelia]

@backspace I believe that error is from how then-redis parses the url. Some redis providers include dummy username (after the // and before the :) that you will want to remove or replace with a numeric database index.

[backspace]

Ah, thanks. With just redis://password@host:port it failed totally, but it worked with redis://0:password@host:port. I can make a PR to update the README, but I’m new to Redis and don’t understand the implications of specifying a database index like that. When I used a configuration object with its host, port, and password, I didn’t specify an index; was it just choosing 0 by default?

[backspace]

Never mind, I see that it does choose 0 by default.