Docker image does not work with Google Memorystore Redis instances

[ckoenig]

The Docker image is using Sidekiq 5.2.8. That version of Sidekiq still tries to set a client name for the Redis connection. This feature has been disabled by default in Sidekiq 6.0.7 by sidekiq/sidekiq#4479.

The problem is that SaaS providers, e.g. Google Cloud, might block calls to the CLIENT command in Redis. Thus sidekiq-prometheus-exporter fails to connect to Google Memorystore Redis instances.

There probably two options to fix this:

1. Update the sidekiq gem version used by the Docker image. However, I don't know if there was a specific reason to pick that version.
2. Update config.ru to handle some additional environment variable, e.g. REDIS_DISABLE_ID, and based on that add id: nil to the config hash for Sidekiq.

I'm happy to prepare a PR if needed. But I would need to know, what the preferred approach would be.

[Strech]

@ckoenig Hey! Yes, to nil the id is the correct approach 👍🏼
Any help is welcome ❤️