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1
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""" |
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2
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This module provides code to automatically load environment variables from the container. |
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3
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It is built on top of (and requires) pydantic. |
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4
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5
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At first one or more classes representing the required environment variables are defined. |
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6
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All environment variables are assumed to be all uppercase and are automatically lowercased. |
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7
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8
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class MyWebEnv(Env): |
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port: str |
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10
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host: str |
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11
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12
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class DBEnv(Env): |
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db_host: str |
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14
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db_password: str |
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15
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16
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17
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@bind_to_container(c) |
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18
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def some_function(env: DBEnv): |
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19
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do_something(env.db_host, env.db_password) |
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21
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""" |
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22
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23
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1 |
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import os |
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24
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1 |
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from abc import ABC |
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25
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1 |
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from typing import ClassVar, Optional |
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26
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27
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1 |
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from .exceptions import MissingEnvVariable, InvalidEnvironmentVariables |
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28
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29
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1 |
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_is_pydantic_v1 = False |
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30
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31
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1 |
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try: |
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32
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1 |
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from pydantic import BaseModel, ValidationError |
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33
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34
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1 |
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try: |
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35
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1 |
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from pydantic import v1 |
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36
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except ImportError as _: |
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37
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_is_pydantic_v1 = True |
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38
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except ImportError as error: |
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39
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raise ImportError( |
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40
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"Using Env requires pydantic to be installed. Try `pip install lagom[env]`" |
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41
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) from error |
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42
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43
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44
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1 |
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class Env(ABC, BaseModel): |
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45
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""" |
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46
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This class implements logic to automatically load properties from ENV |
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47
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variables. |
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48
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""" |
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49
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50
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1 |
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PREFIX: ClassVar[Optional[str]] = None |
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51
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52
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1 |
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def __init__(self, **kwargs): |
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53
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""" |
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54
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For normal usage no arguments should be supplied to the constructor. |
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55
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When this happens all required variables will be loaded from the Environment. |
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56
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For testing you may want to create an instance with variables explicitly set |
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57
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in the constructor. |
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58
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59
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:param kwargs: |
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60
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""" |
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61
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1 |
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try: |
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62
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1 |
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if len(kwargs) == 0: |
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63
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1 |
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prefix = self._prefix() |
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64
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1 |
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envs = os.environ.items() |
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65
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1 |
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super().__init__( |
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66
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**{ |
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67
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key.replace(prefix, "").lower(): value |
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68
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for (key, value) in envs |
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69
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if key.startswith(prefix) |
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70
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} |
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71
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) |
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72
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else: |
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73
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super().__init__(**kwargs) |
|
74
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1 |
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except ValidationError as validation_error: |
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75
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1 |
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if _is_pydantic_v1: |
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76
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missing_field_errors = [ |
|
77
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e |
|
78
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for e in validation_error.errors() |
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79
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if e["type"] == "value_error.missing" |
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80
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] |
|
81
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else: |
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82
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1 |
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missing_field_errors = [ |
|
83
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e for e in validation_error.errors() if e["type"] == "missing" |
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84
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] |
|
85
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1 |
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if missing_field_errors: |
|
86
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1 |
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env_names = self._env_names_from_pydantic_errors(missing_field_errors) |
|
87
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1 |
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raise MissingEnvVariable(env_names) from validation_error |
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88
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1 |
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other_field_errors = [ |
|
89
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e |
|
90
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for e in validation_error.errors() |
|
91
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if e["type"] != "value_error.missing" |
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92
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] |
|
93
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1 |
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env_names = self._env_names_from_pydantic_errors(other_field_errors) |
|
94
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1 |
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raise InvalidEnvironmentVariables( |
|
95
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env_names, str(validation_error) |
|
96
|
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) from validation_error |
|
97
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|
98
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1 |
|
def _env_names_from_pydantic_errors(self, missing_field_errors): |
|
99
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1 |
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return [ |
|
100
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|
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f"{self._prefix()}{pyd_error['loc'][0]}".upper() |
|
101
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for pyd_error in missing_field_errors |
|
102
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] |
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103
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|
104
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1 |
|
def _prefix(self): |
|
105
|
1 |
|
prefix = f"{self.PREFIX}_" if self.PREFIX else "" |
|
106
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|
|
return prefix |
|
107
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|
meadsteve /
lagom
