Add ability to list out environmental variables used for configuration

[matthewfeickert]

There are multiple environmental variables that can affect the RECAST config

recast-atlas/src/recastatlas/config.py

Lines 22 to 72 in 63d06a7

	class Config(object):
	@property
	def default_run_backend(self):
	return os.environ.get('RECAST_DEFAULT_RUN_BACKEND', 'docker')
	def default_build_backend(self):
	return os.environ.get('RECAST_DEFAULT_BUILD_BACKEND', 'docker')
	@property
	def backends(self):
	return {
	"local": {
	"metadata": {
	"short_description": "runs locally with natively installed tools"
	},
	"fromstring": conf_from_env(
	"RECAST_LOCAL_BACKENDSTRING", "multiproc:auto"
	),
	},
	"docker": {
	"metadata": {"short_description": "runs with containerized tools"},
	"fromstring": conf_from_env(
	"RECAST_DOCKER_BACKENDSTRING", "multiproc:auto"
	),
	"image": conf_from_env(
	"RECAST_DOCKER_IMAGE", "recast/recastatlas:v0.1.8"
	),
	"cvmfs": {"location": "/cvmfs", "propagation": "rprivate"},
	"reg": {
	"user": conf_from_env("RECAST_REGISTRY_USERNAME"),
	"pass": conf_from_env("RECAST_REGISTRY_PASSWORD"),
	"host": conf_from_env("RECAST_REGISTRY_HOST"),
	},
	"schema_load_token": conf_from_env("YADAGE_SCHEMA_LOAD_TOKEN"),
	"init_token": conf_from_env("YADAGE_SCHEMA_LOAD_TOKEN"),
	"auth_location": conf_from_env("PACKTIVITY_AUTH_LOCATION"),
	},
	"kubernetes": {
	"metadata": {"short_description": "runs on a Kubernetes cluster"},
	"buildkit_addr": conf_from_env(
	"RECAST_KUBERNETES_BUILDKIT_ADDR", 'kube-pod://buildkitd'
	),
	},
	"reana": {
	"metadata": {"short_description": "runs on a REANA deployment"},
	"access_token": conf_from_env('REANA_ACCESS_TOKEN', None),
	"cvmfs_repos": conf_from_env(
	'RECAST_REANA_CVMFS_REPOS', ['atlas.cern.ch', 'atlas-condb.cern.ch']
	),
	},
	}

though these aren't made explicitly clear to users. It would be helpful to add the ability to check all environmental variables that can affect the config by adding something like recast backends config --check, which would act similar to recast backends ls --check in that it would dump all environmental information for backends to stdout.