Metadata-Version: 2.1
Name: FlaskSimpleAuth
Version: 8.0
Summary: Simple authentication, authorization and parameters for Flask, emphasizing configurability
Home-page: https://github.com/zx80/flask-simple-auth
Author: Fabien Coelho
Author-email: flask.auth@coelho.net
License: UNKNOWN
Description: # Flask Simple Auth
        
        Simple authentication, authorization, parameter checks and utils
        for [Flask](https://flask.palletsprojects.com/), controled from
        Flask configuration and the extended `route` decorator.
        
        
        ## Example
        
        The application code below performs authentication, authorization and
        parameter type checks triggered by the extended `route` decorator,
        or per-method shortcut decorators (`get`, `patch`, `post`…).
        There is no clue in the source about what kind of authentication is used,
        which is the point: authentication is managed in the configuration,
        not in the application code.
        The authorization rule is declared explicitely on each function with the
        mandatory `authorize` parameter.
        Path and HTTP/JSON parameters are type checked and converted automatically
        based on type annotations.
        Basically, you just have to implement a type-annotated Python function and
        most of the crust is managed by Flask and FlaskSimpleAuth.
        
        ```Python
        from FlaskSimpleAuth import Flask
        app = Flask("demo")
        app.config.from_envvar("DEMO_CONFIG")
        
        # users belonging to the "patcher" group can patch "whatever/*"
        # the function gets 3 typed parameters: one integer coming from the path (id)
        # and the remaining two ("some", "stuff") are coming from HTTP or JSON request
        # parameters. "some" is mandatory, "stuff" is optional because it has a default.
        # the declared parameter typing is enforced.
        @app.patch("/whatever/<id>", authorize="patcher")
        def patch_whatever(id: int, some: int, stuff: str = "wow"):
            # ok to do it, with parameters "id", "some" & "stuff"
            return "", 204
        ```
        
        Authentication is manage from the application flask configuration
        with `FSA_*` (Flask simple authentication) directives:
        
        ```Python
        FSA_AUTH = "httpd"     # inherit web-serveur authentication
        # or others schemes such as: basic, digest, token (eg jwt), param…
        # hooks must be provided for retrieving user's passwords and
        # checking whether a user belongs to a group, if these features are used.
        ```
        
        If the `authorize` argument is not supplied, the security first approach
        results in the route to be forbidden (*403*).
        
        Various aspects of the implemented schemes can be configured with other
        directives, with reasonable defaults provided so that not much is really
        needed beyond choosing the authentication scheme.
        
        Look at the [demo application](demo/README.md) for a simple full-featured
        application.
        
        
        ## Documentation
        
        This module helps managing authentication, authorizations and parameters
        in a Flask REST application back-end.
        
        ### Features
        
        The module provides a wrapper around the `Flask` class which
        extends its capabilities for managing authentication, authorization and
        parameters.
        
        This is intended for a REST API implementation serving a remote client
        application through HTTP methods called on a path, with HTTP or JSON
        parameters passed in and a JSON result is returned: this help implement
        an authenticated function call over HTTP.
        
        Note that web-oriented flask authentication modules are not really
        relevant in the REST API context, where the server does not care about
        presenting login forms for instance.
        However, some provisions are made so that it can also be used for a web
        application: CORS, login page redirection…
        
        [**Authentication**](#authentication) is available through the `get_user`
        function.
        It is performed on demand when the function is called or when checking for
        permissions.
        The module implements inheriting the web-server authentication,
        password authentication (HTTP Basic, or HTTP/JSON parameters),
        authentication tokens (custom or JWT passed in headers or as a
        parameter), and a fake authentication scheme useful for local application
        testing.
        It allows to have a login route to generate authentication tokens.
        For registration, support functions allow to hash new passwords consistently
        with password checks.
        
        [**Authorizations**](#authorization) are managed by mandatory permission
        declaration on a route (eg a role name, or an object access), and relies
        on supplied functions to check whether a user has this role or can access
        an object.
        
        [**Parameters**](#parameters) expected in the request can be declared, their
        presence and type checked, and they are added automatically as named parameters
        to route functions, skipping the burden of checking them in typical REST functions.
        In practice, importing Flask's `request` global variable is not necessary anymore.
        
        [**Utils**](#utils) include the convenient `Reference` class which allows to
        share possibly thread-local data for import, and CORS handling.
        
        ### Install
        
        Use `pip install FlaskSimpleAuth` to install the module, or whatever
        other installation method you prefer.
        
        Depending on options, the following modules should be installed:
        
        - [passlib](https://pypi.org/project/passlib/) for password management.
        - [cachetools](https://pypi.org/project/cachetools/) and
          [CacheToolsUtils](https://pypi.org/project/cachetoolsutils/) for caching.
        - [bcrypt](https://pypi.org/project/bcrypt/)  for password hashing (default algorithm).
        - [PyJWT](https://pypi.org/project/PyJWT/) for JSON Web Token (JWT).
        - [cryptography](https://pypi.org/project/cryptography/) for pubkey-signed JWT.
        - [Flask HTTPAuth](https://github.com/miguelgrinberg/Flask-HTTPAuth) for `http-*` authentication options.
        - [Flask CORS](https://github.com/corydolphin/flask-cors) for CORS handling.
        
        ### Initialization
        
        The module is simply initialize by calling its `Flask` constructor
        and providing a configuration through `FSA_*` directives, or possibly
        by calling some methods to register helper functions, such as:
        
         - a function to retrieve the password hash from the user name.
         - a function which tells whether a user is in a group or role.
         - functions which define object ownership.
        
        ```Python
        from FlaskSimpleAuth import Flask
        app = Flask("acme")
        app.config.from_envvar("ACME_CONFIG")
        
        # register some hooks
        
        # return password hash if any (see with FSA_GET_USER_PASS)
        @app.get_user_pass
        def get_user_pass(user):
            return …
        
        # return whether user is in group (see with FSA_USER_IN_GROUP)
        @app.user_in_group
        def user_in_group(user, group):
            return …
        
        # return whether user can access the foo object for an operation
        @app.object_perms("foo")
        def allow_foo_access(user, fooid, mode):
            return …
        ```
        
        Once initialized `app` is a standard Flask object with some additions:
        
        - `route` decorator, an extended version of Flask's own with an `authorize`
          parameter and transparent management of request parameters.
        - per-method shortcut decorators `post`, `get`, `put`, `patch` and `delete`
          which support the same extensions.
        - `user_in_group`, `get_user_pass` and `object_perms` functions/decorators to
          register authentication and authorization helper functions.
        - `get_user` to extract the authenticated user or raise an `FSAException`.
        - `current_user` to get the authenticated user if any, or `None`.
        - `hash_password` and `check_password` to hash or check a password.
        - `create_token` to compute a new authentication token for the current user.
        - `clear_caches` to clear internal process caches (probably a bad idea).
        - `cast` a function/decorator to register no str to some type casts for
          parameters.
        
        It is also possible, but *not* recommended to use the flask extensions model,
        in which case the `FlaskSimpleAuth` object must be instanciated and routes
        *must* be created using this object:
        
        ```Python
        from flask import Flask
        app = Flask("demo")
        app.config.from_envvar("DEMO_CONFIG")
        
        from FlaskSimpleAuth import FlaskSimpleAuth
        fsa = FlaskSimpleAuth(app)
        
        # imaginary blueprint registration on the fsa object:
        from DemoAdmin import abp
        fsa.register_blueprint(abp, url_path="/admin")
        
        # define a route with an optional paramater "flt"
        @fsa.get("/what", authorize="ALL")
        def get_what(flt: str = None):
            …
        ```
        
        ### Authentication
        
        The main authentication configuration directive is `FSA_AUTH` which governs the
        authentication methods used by the `get_user` function, as described in the
        following sections. Defaut is `httpd`.
        
        If a non-token single scheme is provided, authentication will be `token`
        followed by the provided scheme, i.e. `token` are tried first anyway.
        
        To take full control of authentication scheme, provide an ordered list.
        Note that it does not always make much sense to mix some schemes, e.g.
        *basic* and *digest* password storage assumptions are distinct and should
        not be merged.  Also, only one HTTPAuth-based scheme can be active at a time.
        
        Authentication is *always* performed on demand, either to check for a route
        authorization declared with `authorize` or when calling `get_user`.
        
        The authentication scheme attempted on a route can be altered with the `auth`
        parameter added to the `route` decorator.
        This may be used to restrict the authentication scheme to a *subset* if those
        configured globally, and may or may not work otherwise depending on module
        internals.
        This feature is best avoided but in very particular cases because it counters
        a goal of this module which is to remove authentication considerations from the
        code and put them in the configuration only.
        A legitimate use for a REST API is to have `FSA_AUTH` defined to *token* and have
        only one *basic* route to obtain the token used by other routes.
        
        #### Authentication Schemes
        
        The available authentication schemes are:
        
        - `none`
        
          Use to disactivate authentication.
        
        - `httpd`
        
          Inherit web server supplied authentication through `request.remote_user`.
          This is the default.
        
          There are plenty authentication schemes available in a web server such as
          [Apache](https://httpd.apache.org/) or [Nginx](https://nginx.org/), all of
          which probably more efficiently implemented than this python code, so it
          should be the preferred option.
          However, it could require significant configuration effort compared to
          the application-side approach.
        
        - `basic`
        
          HTTP Basic password authentication, which rely on the `Authorization`
          HTTP header in the request.
          Directive `FSA_REALM` provides the authentication realm.
        
          See also [Password Management](#password-management) below for
          how the password is retrieved and checked.
        
        - `http-basic`
        
          Same as previous based on [flask-HTTPAuth](https://pypi.org/project/Flask-HTTPAuth/).
        
          Directive `FSA_REALM` provides the authentication realm.
          Directive `FSA_HTTP_AUTH_OPTS` allow to pass additional options to the
          HTTPAuth authentication class.
        
        - `param`
        
          HTTP or JSON parameter for password authentication.
          User name and password are passed as request parameters.
        
          The following configuration directives are available:
        
          - `FSA_PARAM_USER` parameter name for the user name.
            Default is `USER`.
          - `FSA_PARAM_PASS` parameter name for the password.
            Default is `PASS`.
        
          See also [Password Management](#password-management) below for
          the password is retrieved and checked.
        
        - `password`
        
          Tries `basic` then `param` authentication.
        
        - `http-digest` or `digest`
        
          HTTP Digest authentication based on [flask-HTTPAuth](https://pypi.org/project/Flask-HTTPAuth/).
        
          Note that the implementation relies on *sessions*, which may require
          the `SECRET_KEY` option to be set to something.
          The documentation states that server-side sessions are needed because
          otherwise the *nonce* and *opaque* parameters could be reused, which
          may be a security issue under some conditions. I'm unsure about that,
          but I agree that client-side cookie sessions are strange things best
          avoided if possible.
        
          Directive `FSA_REALM` provides the authentication realm.
          Directive `FSA_HTTP_AUTH_OPTS` allow to pass additional options to the
          HTTPAuth authentication class, such as `use_ha1_pw`, as a dictionary.
        
          See also [Password Management](#password-management) below for
          how the password is retrieved and checked. Note that password management
          is different for digest authentication because the simple hash of the
          password or the password itself is needed for the verification.
        
        - `token`
        
          Only rely on signed tokens for authentication.
          A token certifies that a *user* is authenticated in a *realm* up to some
          time *limit*.
          The token is authenticated by a signature which is usually the hash of the
          payload (*realm*, *user* and *limit*) and a secret hold by the server.
        
          There are two token types chosen with the `FSA_TOKEN_TYPE` configuration
          directive: `fsa` is a simple compact readable custom format, and `jwt`
          [RFC 7519](https://tools.ietf.org/html/rfc7519) standard based
          on [PyJWT](https://pypi.org/project/PyJWT/) implementation.
        
          The `fsa` token syntax is: `<realm>:<user>:<limit>:<signature>`,
          for instance: `comics:calvin:20380119031407:4ee89cd4cc7afe0a86b26bdce6d11126`.
          The time limit is a simple UTC timestamp *YYYYMMDDHHmmSS* that
          can be checked easily by the application client.
          Compared to `jwt` tokens, they are easy to interpret and compare manually,
          no decoding is involved.
        
          The following configuration directives are available:
        
          - `FSA_TOKEN_TYPE` type of token, either *fsa*, *jwt* or `None` to disable.
            Default is *fsa*.
          - `FSA_TOKEN_CARRIER` how to transport the token: *bearer* (`Authorization`
            HTTP header), *param*, *cookie* or *header*.
            Default is *bearer*.
          - `FKA_TOKEN_NAME` name of parameter or cookie holding the token, or
            bearer scheme, or header name.
            Default is `AUTH` for *param* carrier, `auth` for *cookie* carrier,
            `Bearer` for HTTP Authentication header (*bearer* carrier),
            `Auth` for *header* carrier.
          - `FSA_REALM` realm of authentication for token, basic or digest.
            Default is the simplified lower case application name.
            For *jwt*, this is translated as the audience.
          - `FSA_TOKEN_SECRET` secret string used for validating tokens.
            Default is a system-generated random string containing 256 bits.
            This default will only work with itself, as it is not shared
            across server instances or processes.
          - `FSA_TOKEN_SIGN` secret string used for signing tokens, if
            different from previous secret. This is only relevant for public-key
            *jwt* schemes (`R…`, `E…`, `P…`).
            Default is to use the previous secret.
          - `FSA_TOKEN_DELAY` number of minutes of token validity.
            Default is *60* minutes.
          - `FSA_TOKEN_GRACE` number of minutes of grace time for token validity.
            Default is *0* minutes.
          - `FSA_TOKEN_ALGO` algorithm used to sign the token.
            Default is `blake2s` for `fsa` and `HS256` for *jwt*.
          - `FSA_TOKEN_LENGTH` number of hash bytes kept for token signature.
            Default is *16* for `fsa`. The directive is ignored for `jwt`.
        
          Function `create_token(user)` creates a token for the user depending
          on the current scheme. If `user` is not given, the current user is taken.
        
          Token authentication is always attempted unless the secret is empty.
          Setting `FSA_AUTH` to `token` results in *only* token authentication to be used.
        
          Token authentication is usually much faster than password verification because
          password checks are designed to be slow so as to hinder password cracking,
          whereas token authentication relies on simple hashing for its security.
          Another benefit of token is that it avoids sending passwords over and over.
          The rational option is to use a password scheme to retrieve a token and then to
          use it till it expires. This can be enforced by setting `FSA_AUTH` to `token`
          and to only add `auth="basic"` on the login route.
        
          Token expiration can be understood as a kind of automatic logout, which suggests
          to choose the delay with some care depending on the use case.
        
          When the token is carried as a *cookie*, it is automatically updated when 25% of
          the delay remains, if possible.
        
          Internally *jwt* token checks are cached so that even with slow public-key schemes
          the performance impact should be low.
        
        - `http-token`
        
          Token scheme based on [flask-HTTPAuth](https://pypi.org/project/Flask-HTTPAuth/).
          Carrier is *bearer* or *header*.
        
          Directive `FSA_HTTP_AUTH_OPTS` allow to pass additional options to the
          HTTPAuth authentication class, such as `header`, as a dictionary.
        
        - `fake`
        
          Trust a parameter for authentication claims.
          Only for local tests, obviously.
          This is enforced.
        
          - `FSA_FAKE_LOGIN` name of parameter holding the user name.
            Default is `LOGIN`.
        
        
        #### Password Management
        
        Password authentication is performed for the following authentication
        schemes: `param`, `basic`, `http-basic`, `http-digest`, `digest`, `password`.
        
        For checking passwords the password (salted hash) must be retrieved through
        `get_user_pass(user)`.
        This function must be provided by the application when the module is initialized.
        Because this function is cached by default, the cache expiration must
        be reached so that changes take effect, or the cache must be cleared
        manually, which may impair application performance.
        
        The following configuration directives are available to configure
        `passlib` password checks:
        
         - `FSA_PASSWORD_SCHEME` password scheme to use for passwords.
           Default is `bcrypt`.
           See [passlib documentation](https://passlib.readthedocs.io/en/stable/lib/passlib.hash.html)
           for available options.
           Set to `None` to disable password checking.
         - `FSA_PASSWORD_OPTS` relevant options (for `passlib.CryptContext`).
           Default is `{'bcrypt__default_rounds': 4, 'bcrypt__default_ident': '2y'}`.
        
        Beware that modern password checking is often pretty expensive in order to
        thwart password cracking if the hashed passwords are leaked, so that you
        do not want to have to use that on every request in real life (eg *hundreds*
        milliseconds for passlib bcrypt *12* rounds).
        The above defaults result in manageable password checks of a few milliseconds.
        Consider using tokens to reduce the authentication load on each request.
        
        For `digest` authentication, the password must be either in *plaintext* or a
        simple MD5 hash ([RFC 2617](https://www.rfc-editor.org/rfc/rfc2617.txt)).
        The authentication setup must be consistent (set `use_ha1_pw` as *True* for the
        later).
        As retrieving the stored information is enough to steal the password (plaintext)
        or at least impersonate a user (hash), consider avoiding `digest` altogether.
        HTTP Digest Authentication only makes sense for unencrypted connexions, which
        are a bad practice anyway.
        It is just provided here for completeness.
        
        Function `hash_password(pass)` computes the password salted digest compatible
        with the current configuration, and may be used for setting or resetting
        passwords. An opened route for user registration with mandatory parameters
        could look like that:
        
        ```Python
        @app.post("/register", authorize="ANY")
        def post_register(user: str, password: str):
            if user_already_exists(user):
                return f"cannot create {user}", 409
            add_new_user_with_hashed_pass(user, app.hash_password(password))
            return "", 201
        ```
        
        Because password checks are usually expensive, it is advisable to switch
        to `token` authentication. A token can be created on a path authenticated
        by a password method:
        
        ```Python
        # token creation route for all registered users
        @app.get("/login", authorize="ALL")
        def get_login():
            return jsonify(app.create_token()), 200
        ```
        
        The client application will return the token as a parameter or in
        headers for authenticating later requests, till it expires.
        
        
        ### Authorization
        
        Authorizations are declared with the `authorize` parameter to
        the `route` decorator (and its per-method shortcuts).
        The modules supports two permission models:
        
         - a group-oriented model
         - an object-oriented model
        
        The parameter accepts a list of `str` and `int` for groups, and of
        `tuple` for object permissions.  If a scalar is provided, it is assumed
        to be equivalent to a list of one element.
        
        When multiple authorizations are provided they are cumulative,
        that is all conditions must be met.
        
        #### Group Authorizations
        
        A group or role is identified as an integer or a string.
        The `user_in_group(user, group)` function is called to check whether the
        authenticated user belongs to a given group.
        Because this function is cached by default, the cache expiration must
        be reached so that changes take effect, or the cache must be cleared
        manually, which may impair application performance.
        
        ```Python
        @app.get("/admin-only", authorize="ADMIN")
        def get_admin_only():
            # only authenticated "ADMIN" users can get here!
            …
        ```
        
        There are three special values that can be passed to the `authorize` decorator:
        
         - `ANY` declares that no authentication is needed on that route.
         - `ALL` declares that all authenticated user can access this route, without group checks.
         - `NONE` returns a *403* on all access. It can be used to close a route
           temporarily. This is the default.
        
        ```Python
        @app.get("/closed", authorize=NONE)
        def get_closed():
            # nobody can get here
        
        @app.get("/authenticated", authorize=ALL)
        def get_authenticated():
            # ALL authenticated users can get here
        
        @app.get("/opened", authorize=ANY)
        def get_opened():
            # ANYone can get here, no authentication is required
        ```
        
        Note that this simplistic model does is not enough for non-trivial applications,
        where permissions on objects often depend on the object owner.
        For those, careful per-object and per-operation authorization will still be needed.
        
        #### Object Authorizations
        
        Non trivial application have access permissions which depend on the data
        stored by the application. For instance, a user may alter a data because
        they *own* it, or access a data because they are *friends* of the owner.
        
        In order to implement this model, the `authorize` decorator parameter can
        hold a tuple `(domain, variable, mode)` which designates a permission domain
        (eg a table or object or concept name in the application), the name of
        a variable in the request (path or HTTP or JSON parameters) which identifies
        an object of the domain, and the operation or level of access necessary for
        this route:
        
        ```Python
        @app.get("/message/<mid>", authorize=("msg", "mid", "read"))
        def get_message_mid(mid: int):
            …
        ```
        
        The system will check whether the current user can access message *mid*
        in *read* mode by calling a per-domain user-supplied function:
        
        ```Python
        @app.object_perms("msg")
        def can_access_message(user: str, mid: int, mode: str) -> bool:
            # can user access message mid for operation mode?
            return …
        
        # also: app.object_perms("msg", can_access_message)
        ```
        
        If the check function returns *None*, a *404 Not Found* response is generated.
        If it returns *False*, a *403 Forbidden* response is generated.
        If it returns *True*, the route function is called to generate the response.
        
        If `mode` is not supplied, *None* is passed to the check function.
        If `variable` is not supplied, the *first* parameter of the route function
        is taken:
        
        ```Python
        # same as authorize=("msg", "mid", None)
        @app.patch("/message/<mid>", authorize=("msg",))
        def patch_message_mid(mid: int):
            …
        ```
        
        The `FSA_OBJECT_PERMS` configuration directive can be set as a dictionary
        which maps domains to their access checking functions:
        
        ```Python
        FSA_OBJECT_PERMS = { "msg": can_access_message, "blog": can_access_blog }
        ```
        
        Because these functions are cached by default, the cache expiration must
        be reached so that changes take effect, or the cache must be cleared
        manually, which may impair application performance.
        
        
        ### Parameters
        
        Request parameters (HTTP or JSON) are translated automatically to named function
        parameters, by relying on function type annotations.
        Parameters are considered mandatory unless a default value is provided.
        
        ```python
        @app.get("/something/<id>", authorize=…)
        def get_something_id(id: int, when: date, what: str = "nothing"):
            # `id` is an integer path-parameter
            # `when` is a mandatory date HTTP or JSON parameter
            # `what` is an optional string HTTP or JSON parameter
            return …
        ```
        
        Request parameter string values are actually *converted* to the target type.
        For `int`, base syntax is accepted for HTTP/JSON parameters, i.e. `0x11`,
        `0o21`, `0b10001` and `17` all mean decimal *17*.
        For `bool`, *False* is an empty string, `0`, `False` or `F`, otherwise
        the value is *True*.
        Type `path` is a special `str` type which allows to trigger accepting
        any path on a route.
        Type `JsonData` is a special type to convert, if necessary, a string value
        to JSON, expecting a list or a dictionary.
        
        If one parameter is a dict of keyword arguments, all request parameters are
        provided into it, as shown below:
        
        ```Python
        @app.put("/awesome", authorize="ALL")
        def put_awesome(**kwargs):
            …
        ```
        
        Custom classes can be used as path and HTTP parameter types, provided that
        the constructor accepts a string to convert the parameter value to the
        expected type.
        
        ```Python
        class EmailAddr:
            def __init__(self, addr: str):
                self._addr = addr
        
        @app.get("/mail/<addr>", authorize="ALL")
        def get_mail_addr(addr: EmailAddr):
            …
        ```
        
        If the constructor does not match, a custom function can be provided
        with the `cast` function/decorator and will be called automatically
        to convert parameters:
        
        ```Python
        class House:
            …
        
        @app.cast(House)
        def strToHouse(s: str) -> House:
            return …
        
        # or: app.cast(House, strToHouse)
        
        @app.get("/house/<h>", authorize="ANY")
        def get_house_h(h: House)
            …
        ```
        
        The `FSA_CAST` directive can also be defined as a dictionary mapping
        types to their conversion functions:
        
        ```Python
        FSA_CAST = { House: strToHouse, … }
        ```
        
        Finally, python parameter names can be prepended with a `_`,
        which is ignored when translating HTTP parameters.
        This allows to use python keywords as parameter names, such
        as `pass` or `def`.
        
        ```Python
        @app.put("/user/<pass>", authorize="ALL")
        def put_user_pass(_pass: str, _def: str, _import: str):
            …
        ```
        
        ### Utils
        
        Utilities include the `Reference` generic object wrapper class and
        miscellaneous configuration directives which cover security,
        caching and CORS.
        
        #### `Reference` Object Wrapper
        
        This class implements a generic share-able global variable which can be
        used by modules (eg app, blueprints…) with its initialization differed.
        
        Under the hood, most methods calls are forwarded to a possibly thread-local
        object stored inside the wrapper, so that the Reference object mostly
        behaves like the wrapped object itself.
        
        The wrapped object can be set or reset at will with `set_obj`.
        For thread-local objects, a function to generate the expected shared object
        must be provided with `set_fun` or as the `fun` parameter to the constructor.
        The `set` method prefix can be changed with the `set_name` initialization
        parameter.
        
        ```Python
        # file Shared.py
        from FlaskSimpleAuth import Reference
        stuff = Reference()
        def init_app(**conf):
            stuff.set_obj(…)
        ```
        
        Then in a blueprint:
        
        ```Python
        # file SubStuff.py
        from FlaskSimpleAuth import Blueprint
        from Shared import stuff
        
        sub = Blueprint(…)
        
        @sub.get("/stuff", authorize="ALL"):
        def get_stuff():
            return str(stuff), 200
        ```
        
        Then in the app itself:
        
        ```Python
        # file App.py
        from FlaskSimpleAuth import Flask
        app = Flask(__name__)
        
        from SubStuff import sub
        app.register_blueprint(sub, url_prefix="/sub")
        
        # deferred "stuff" initialization
        import Shared
        Shared.init_app(…)
        
        …
        ```
        
        When using a thread-local object, the generation function is passed an integer
        which is the invocation number, starting from 0. Attribute `_nthreads` stores
        the total number of objects created.
        
        ### Miscellaneous Configuration Directives
        
        Some directives govern various details for this extension internal working.
        
        - `FSA_SECURE` only allows secured requests on non-local connections.
          Default is *True*
        
        - `FSA_SERVER_ERROR` controls the status code returned on the module internal
          errors, to help distinguish these from other internal errors which may occur.
          Default is *500*.
        
        - `FSA_NOT_FOUND_ERROR` controls the status code returned when a permission
          checks returns *None*.
          Default is *404*.
        
        - `FSA_DEBUG` set module in debug mode, generating excessive traces…
          Default is *False*.
        
        - `FSA_LOGGING_LEVEL` adjust module internal logging level.
          Default is *None*.
        
        Some control is available about caching features used for user authentication
        (user password access and token validations) and authorization (group and
        per-object permissions):
        
        - `FSA_CACHE` controls the type of cache to use, set to *None* to disallow
          caches. Values for standard `cachetools` cache classes are `ttl`, `lru`,
          `lfu`, `mru`, `fifo`, `rr` plus `dict`.
          MemCached is supported by setting it to `memcached`, and Redis with `redis`.
          Default is `ttl`.
        
        - `FSA_CACHE_OPTS` sets internal cache options with a dictionary.
          This must contain the expected connection parameters for `pymemcache.Client`
          and for `redis.Redis` redis, for instance.
          For `redis` and `ttl`, an expiration ttl of 10 minutes is used and can be
          overwritten by providing the `ttl` parameter.
        
        - `FSA_CACHE_SIZE` controls size of internal `cachetools` caches.
          Default is *262144*, which should use a few MiB.
          *None* means unbounded, more or less.
        
        Web-application oriented features:
        
        - `FSA_401_REDIRECT` url to redirect to on *401*.
          Default is *None*.
          This can be used for a web application login page.
        
        - `FSA_URL_NAME` name of parameter for the target URL after a successful login.
          Default is `URL` if redirect is activated, else *None*.
          Currently, the login page should use this parameter to redirect to when ok.
        
        - `FSA_CORS` and `FSA_CORS_OPTS` control CORS (Cross Origin Resource Sharing) settings.
        
          [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing) is a
          security feature implemented by web browsers to check whether a server
          accepts requests from a given origin (*i.e.* from JavaScript code
          provided by some domain).
        
          CORS request handling is enabled by setting `FSA_CORS` to *True* which
          allows requests from any origin. Default is *False*.
          Additional options are controled with `FSA_CORS_OPTS`.
          The implementation is delegated to the
          [`flask_cors`](https://pypi.org/project/Flask-Cors/) Flask extension
          which must be available if the feature is enabled.
        
        
        ## License
        
        This software is *public domain*.
        All software has bug, this is software, hence…
        Beware that you may lose your hairs or your friends because of it.
        If you like it, feel free to send a postcard to the author.
        
        
        ## Versions
        
        Sources are available on [GitHub](https://github.com/zx80/flask-simple-auth)
        and packaged on [PyPI](https://pypi.org/project/FlaskSimpleAuth/).
        
        Latest version is *8.0* published on 2022-03-04.
        Initial version was *0.9.0* on 2021-02-21.
        
        See [all versions](VERSIONS.md).
        
        
        ## TODO
        
        - thread-local stuff in Reference: what about teardown?
        - what about asyncio?
        - test `FSA_HTTP_AUTH_OPTS`?
        - add `any` token scheme?
        - add app.log?
        - on-demand supplied user data?
          `get\_identity(user: str) -> Any` which is to be cached
          registered with `app.identity(get_identity)`
          then `id = app.get_identity(user: str = app.get_user())`
          does it really need to be inside `FlaskSimpleAuth`?
          possibly the id can be passed to perm hooks instead of the login?
          can be managed there as well?
        - reduce cloc?
        
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: License :: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Classifier: Programming Language :: Python
Classifier: Environment :: Web Environment
Classifier: Framework :: Flask
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Description-Content-Type: text/markdown
