Support more Flask Rate Limiter Configuration

[phillipjohnson]

There is currently a minimal configuration of the Flask Rate Limiter plugin available via environment variables. However, this does not fully encapsulate what the plugin can do.

Most importantly in our environment, we run the application behind a load balancer. Because of that, all requests come in from the same IP address. To find the true client IP, the X-Forwarded-For header must be inspected. The plugin seems to support this, see Deploying an application behind a proxy. However, we have no capacity to enable that within Redash as it is currently deployed.

I would suggest expanding the list of environment variables to provide more flexibility of the rate limiter.

[yoshiokatsuneo]

@phillipjohnson

How about setting REDASH_PROXIES_COUNT environment variable to set the number of proxies(default value is 1) between Flask and the client ?

[phillipjohnson]

Ah, I missed that one, will take a look!