122 lines
3.5 KiB
Python
122 lines
3.5 KiB
Python
"""
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Utility methods for use in jupyterhub_config.py and dynamic subconfigs.
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Methods here can be imported by extraConfig in values.yaml
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"""
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import os
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from collections.abc import Mapping
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from functools import lru_cache
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import yaml
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# memoize so we only load config once
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@lru_cache
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def _load_config():
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"""Load the Helm chart configuration used to render the Helm templates of
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the chart from a mounted k8s Secret, and merge in values from an optionally
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mounted secret (hub.existingSecret)."""
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cfg = {}
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for source in ("secret/values.yaml", "existing-secret/values.yaml"):
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path = f"/usr/local/etc/jupyterhub/{source}"
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if os.path.exists(path):
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print(f"Loading {path}")
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with open(path) as f:
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values = yaml.safe_load(f)
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cfg = _merge_dictionaries(cfg, values)
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else:
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print(f"No config at {path}")
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return cfg
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@lru_cache
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def _get_config_value(key):
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"""Load value from the k8s ConfigMap given a key."""
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path = f"/usr/local/etc/jupyterhub/config/{key}"
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if os.path.exists(path):
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with open(path) as f:
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return f.read()
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else:
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raise Exception(f"{path} not found!")
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@lru_cache
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def get_secret_value(key, default="never-explicitly-set"):
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"""Load value from the user managed k8s Secret or the default k8s Secret
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given a key."""
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for source in ("existing-secret", "secret"):
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path = f"/usr/local/etc/jupyterhub/{source}/{key}"
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if os.path.exists(path):
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with open(path) as f:
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return f.read()
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if default != "never-explicitly-set":
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return default
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raise Exception(f"{key} not found in either k8s Secret!")
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def get_name(name):
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"""Returns the fullname of a resource given its short name"""
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return _get_config_value(name)
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def get_name_env(name, suffix=""):
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"""Returns the fullname of a resource given its short name along with a
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suffix, converted to uppercase with dashes replaced with underscores. This
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is useful to reference named services associated environment variables, such
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as PROXY_PUBLIC_SERVICE_PORT."""
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env_key = _get_config_value(name) + suffix
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env_key = env_key.upper().replace("-", "_")
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return os.environ[env_key]
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def _merge_dictionaries(a, b):
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"""Merge two dictionaries recursively.
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Simplified From https://stackoverflow.com/a/7205107
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"""
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merged = a.copy()
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for key in b:
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if key in a:
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if isinstance(a[key], Mapping) and isinstance(b[key], Mapping):
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merged[key] = _merge_dictionaries(a[key], b[key])
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else:
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merged[key] = b[key]
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else:
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merged[key] = b[key]
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return merged
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def get_config(key, default=None):
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"""
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Find a config item of a given name & return it
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Parses everything as YAML, so lists and dicts are available too
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get_config("a.b.c") returns config['a']['b']['c']
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"""
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value = _load_config()
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# resolve path in yaml
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for level in key.split("."):
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if not isinstance(value, dict):
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# a parent is a scalar or null,
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# can't resolve full path
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return default
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if level not in value:
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return default
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else:
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value = value[level]
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return value
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def set_config_if_not_none(cparent, name, key):
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"""
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Find a config item of a given name, set the corresponding Jupyter
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configuration item if not None
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"""
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data = get_config(key)
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if data is not None:
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setattr(cparent, name, data)
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