Docs update to reflect other environmental variables available in the docker image

[doublebyte1]

Overview

There are quite a few environmental variables about server behaviour that can be injected into the docker image:

pygeoapi/docker/entrypoint.sh

Lines 43 to 52 in 4fba2a4

	# gunicorn env settings with defaults
	SCRIPT_NAME=${SCRIPT_NAME:=/}
	CONTAINER_NAME=${CONTAINER_NAME:=pygeoapi}
	CONTAINER_HOST=${CONTAINER_HOST:=0.0.0.0}
	CONTAINER_PORT=${CONTAINER_PORT:=80}
	WSGI_APP=${WSGI_APP:=pygeoapi.flask_app:APP}
	WSGI_WORKERS=${WSGI_WORKERS:=4}
	WSGI_WORKER_TIMEOUT=${WSGI_WORKER_TIMEOUT:=6000}
	WSGI_WORKER_CLASS=${WSGI_WORKER_CLASS:=gevent}

This PR adds information about them in the documentation.

Additional information

The server port in particular is quite important to document; as it currently stands, the server is ignoring whatever is set in pygeoapi config, and overriding it with port 80.

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines

[tomkralidis]

Fence 5001 in backticks (5001 -> 5001)

[tomkralidis]

6000 -> 6000.

[tomkralidis]

localhost -> localhost

[webb-ben]

Is the understanding that variables not documented, but used in the entrypoint are adequately documented here? The two env variables I most commonly override here are WSGI_APP and WSGI_WORKER_CLASS to deploy with starlette / uvicorn, but at that point they are no longer WSGI

[doublebyte1]

Is the understanding that variables not documented, but used in the entrypoint are adequately documented here? The two env variables I most commonly override here are WSGI_APP and WSGI_WORKER_CLASS to deploy with starlette / uvicorn, but at that point they are no longer WSGI

To assume that the users will figure out these variables exist without even pointing to the documentation of Gunicorn, seems a bit far fetched; but maybe that is just me... (: