How to reliably determine which PaaS is my project running on?
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11-12-2019 - |
Question
I have a small project that I want to deploy to both Heroku and OpenShift, to try things out on both platforms. I'm using Python/Django So I want to take advantage of the dynamic import feature to define settings per environment, maintaining a settings module for those platforms I want to deploy to, like:
my_project/
settings/
__init__.py <-- This is what's being imported during app init, here is where I want to detect which platform specific settings module to load
dev_settings.py
heroku_settings.py
openshift_settings.py
So far I use this code:
ENVIRONMENT = the_function_or_code_that_returns_the_environment() # Defaults to "dev"
from django.utils.importlib import import_module
try:
# Import any symbols that begin with A-Z. Append to lists any symbols that
# begin with "EXTRA_".
local_settings_module_name = '%s_settings' % ENVIRONMENT
local_settings = import_module(local_settings_module_name)
import re
for attr in dir(local_settings):
match = re.search('^EXTRA_(\w+)', attr)
if match:
name = match.group(1)
value = getattr(local_settings, attr)
try:
globals()[name] += value
except KeyError:
globals()[name] = value
elif re.search('^[A-Z]', attr):
globals()[attr] = getattr(local_settings, attr)
except ImportError:
pass
It would be prefered to detect this via default (not set by me/developer) environment variables. Heroku expose just a few:
DATABASE_URL
ENVIRONMENT
LANG
LD_LIBRARY_PATH
LIBRARY_PATH
PATH
PYTHONHASHSEED
PYTHONHOME
PYTHONPATH
PYTHONUNBUFFERED
SHARED_DATABASE_URL
And OpenShift's:
OPENSHIFT_DB_HOST
OPENSHIFT_LOG_DIR
OPENSHIFT_TMP_DIR
OPENSHIFT_DB_CTL_SCRIPT
OPENSHIFT_REPO_DIR
OPENSHIFT_HOMEDIR
OPENSHIFT_GEAR_NAME
OPENSHIFT_PHPMYADMIN_IP
OPENSHIFT_RUNTIME_DIR
OPENSHIFT_INTERNAL_PORT
OPENSHIFT_PHPMYADMIN_CTL_SCRIPT
OPENSHIFT_DB_MYSQL_51_RESTORE
OPENSHIFT_DB_MYSQL_51_DUMP
OPENSHIFT_DB_PASSWORD
OPENSHIFT_DB_USERNAME
OPENSHIFT_PHPMYADMIN_GEAR_DIR
OPENSHIFT_RUN_DIR
OPENSHIFT_INTERNAL_IP
OPENSHIFT_GEAR_DIR
OPENSHIFT_GEAR_CTL_SCRIPT
OPENSHIFT_APP_DNS
OPENSHIFT_GEAR_TYPE
OPENSHIFT_GEAR_DNS
OPENSHIFT_DB_MYSQL_51_EMBEDDED_TYPE
OPENSHIFT_DB_URL
OPENSHIFT_APP_NAME
OPENSHIFT_DATA_DIR
OPENSHIFT_DB_SOCKET
OPENSHIFT_GEAR_UUID
OPENSHIFT_APP_UUID
OPENSHIFT_DB_TYPE
OPENSHIFT_DB_MYSQL_51_DUMP_CLEANUP
OPENSHIFT_DB_PORT
OpenShift variables are prefixed with OPENSHIFT_
so there's a start, but that's not the case with Heroku.
How can I reliably detect the platform using environment variables?
Solution 2
@Kevin, I'm posting my comment it as an answer, so people can see it quickly (or improve it!):
if len([k for k in os.environ.keys() if k.startswith('OPENSHIFT_')]):
ENVIRONMENT = 'openshift'
elif len([k for k in os.environ.values() if k.find('heroku') > -1]):
ENVIRONMENT = 'heroku'
local_settings_module_name = '%s_settings' % ENVIRONMENT
local_settings = import_module(local_settings_module_name)
# do the magic with the `local_settings` module
OTHER TIPS
I'd recommend setting my own ENV configuration setting. This can be done easily using heroku.
heroku config:add MY_DEPLOYMENT_PLATFORM=heroku
Then, in your initializer (or wherever you need) you can access that value like so:
if ENV["MY_DEPLOYMENT_PLATFORM"] == "heroku"
// perform heroku config
else
// perform other PAAS config
end
This is how I detect the PaaS my app currently on. The overide_settings method isn't mine.
def override_settings(dottedpath):
"""Imports uppercase modules from an string based module.
Example:
override_settings('my.module.settings')
"""
try:
_m = import_module(dottedpath)
except ImportError:
warnings.warn("Failed to import %s" % dottedpath) # <-- will show up in your error log
else:
_thismodule = sys.modules[__name__]
for _k in dir(_m): # <-- moved the block inside else
if _k.isupper() and not _k.startswith('__'): setattr(_thismodule,
_k, getattr(_m, _k))
ON_OPENSHIFT = False
if os.environ.has_key('OPENSHIFT_REPO_DIR'):
ON_OPENSHIFT = True
ON_HEROKU = False
if os.environ.get('LD_LIBRARY_PATH', None) == '/app/.heroku/vendor/lib':
ON_HEROKU = True
if ON_OPENSHIFT:
override_settings('settings.openshift')
if ON_HEROKU:
override_settings('settings.heroku')