FlaskSimpleAuth 18.1

Simple authentication, authorization and parameters for Flask, emphasizing configurability

Flask Simple Auth

Simple authentication, authorization, parameter checks and utils for Flask, 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.

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 from the configuration file (DEMO_CONFIG):

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 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 or managing views, for instance. However, some provisions are made so that it can also be used for a web application: CORS, login page redirection…

Authentication, i.e. checking who is doing the request, 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, various password authentication (HTTP Basic, or HTTP/JSON parameters), tokens (custom or JWT passed in headers or as a parameter), a fake authentication scheme useful for local application testing, or relying on a user provided function to check a password or code. It allows to have a login route to generate authentication tokens. For registration, support functions allow to hash new passwords consistently with password checks. Alternate password checking schemes (eg temporary code, external LDAP server) can be plug in easily through a hook.

Authorizations, i.e. checking whether the above who can perform a request, 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. Authorization can also be provided from a third party through JWT tokens following the OAuth2 approach.

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. The philosophy is that a REST API entry point is a function call through HTTP, so the route definition should be a function, avoiding relying on magic globals.

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 for password management.
• cachetools and CacheToolsUtils for caching.
• ProxyPatternPool for sharing.
• bcrypt for password hashing (default algorithm).
• PyJWT for JSON Web Token (JWT).
• cryptography for pubkey-signed JWT.
• Flask HTTPAuth for http-* authentication options.
• 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.

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 exception.
• current_user to get the authenticated user if any, or None. It can also be requested as a parameter with the CurrentUser type.
• user_oauth to function to check if the current token-authenticated user has some authorizations.
• 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.
• special_parameter a function/decorator to register new special parameter types.
• password_quality a function/decorator to register a function to check for password quality.
• password_check a function/decorator to register a new password checker.

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 is 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 or Nginx, including LDAP or other databases, 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 below for how the password is retrieved and checked.

• http-basic

  Same as previous based on 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 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.

  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 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 standard based on 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. If an issuer is set (FSA_TOKEN_ISSUER), the name is appended to the realm after a /.

  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 Authorization 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_ISSUER the issuer of the token. Default is None.
  • 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.
  • FSA_TOKEN_RENEWAL for cookie token, the fraction of delay under which the cookie/token is renewed automatically. Default is 0.0, meaning no renewal.

  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.

• oauth

  Synonymous to token, but to be used on a route so as to trigger JWT scope authorizations on that route: Authorizations are attached to the current authentification performed through a token. In that case, the authorize groups are interpreted as scopes that must be provided by the token. In order to simplify security implications, scopes and groups (user_in_group) authorizations cannot be mixed on a route: create distinct routes to handle these.

  # /data is only accessible through a trusted JWT token with "read" scope
  @app.get("/data", authorize="read", auth="oauth"):
  def get_data():
      return access_some_data(app.get_user()), 200
  

  Method user_oauth allows to check whether the current user can perform some operation.

• http-token

  Token scheme based on 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.

The provided password management comprises handling password verification in the application, relying on standard password hashing schemes and a user-provided function to retrieve the password hash (get_user_pass), and/or delegating the whole verification process to a user-provided function (password_check).

For checking passwords internally, the password (salted hash) must be retrieved through get_user_pass(user). This function must be provided 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 for available options. Set to None to disable internal 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). 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 by the application for setting or resetting passwords.

This function checks the password quality by relying on:

• FSA_PASSWORD_LEN minimal password length, 0 to disable.
• FSA_PASSWORD_RE list of regular expressions that a password must match.
• FSA_PASSWORD_QUALITY hook function which returns whether the password is acceptable, possibly raising an exception to complain if not. This hook can also be filled with the password_quality method/decorator. It allows to plug a password strength estimator such as zxcvbn.

This application-managed standard password checking can be overridden by providing an alternate password checking function with a directive:

• FSA_PASSWORD_CHECK hook function which returns whether user and password provided is acceptable for said user. This allows to plug a LDAP server or a temporary password recovery scheme or other one-time or limited-time passwords sent by SMS or mail, for instance. This hook can also be filled with the password_check method/decorator. This alternate check is used if the primary check failed or is disactivated.

An opened route for user registration with mandatory parameters could look like that:

@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:

# 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 required through a list, 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.

@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.

@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:

@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:

@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:

# 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:

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.

@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:

@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.

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:

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:

FSA_CAST = { House: strToHouse, … }

As a special case, the Request, Session, Globals, Environ and CurrentUser types, when used for parameters, result in the request, session, g flask special objects, environ WSGI parameter and the current authenticated user to be passed as this parameter to the function, allowing to keep a functional programming style by hidding away these special proxies.

More special parameters can be added with the special_parameter app function/decorator, by providing a type and a function which returns the expected value. For instance, the Request definition corresponds to:

app.special_parameter(Request, lambda: request)

The FSA_SPECIAL_PARAMETER directive can also be defined as a dictionary mapping types to their parameter value function.

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.

@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, a ErrorResponse class to quickly generate error replies and miscellaneous configuration directives which cover security, caching and CORS.

Reference Object Wrapper

This class provides a proxy object based on the Proxy class from ProxyPatternPool.

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 sub-thread-local object stored inside the wrapper, so that the Reference object mostly behaves like the wrapped object itself.

See the module for a detailed documentation.

ErrorResponse class

Raising this exception with a message and status from any user-defined function generates a Response of this status with the text message contents sent to the request.

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_REJECT_UNEXPECTED_PARAM tells whether to reject requests with unexpected parameters. Default is True.

• FSA_DEBUG set module in debug mode, generating excessive traces… Default is False.

• FSA_LOGGING_LEVEL adjust module internal logging level. Default is None.

• FSA_LOCAL sets the internal object isolation level, must be consistent with the module WSGI usage. Possible values are process, thread (several threads can be used by the WSGI server) and werkzeug (should work with sub-thread level request handling, eg greenlets). Default is thread.

Some control is available about internal 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.

• FSA_CACHE_PREFIX use this application-level prefix, useful for shared distributed caches. A good candidate could be app.name + ".". Default is None, meaning no prefix.

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 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 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 and packaged on PyPI.

Latest version is 18.1 published on 2022-11-11. Initial version was 0.9.0 on 2021-02-21.

See all versions.

See Also

Flask-Security is a feature-full web-oriented authentication and authorization framework based on an ORM. By contrast, Flask Simple Auth:

• does NOT assume any ORM or impose a data model, you only have to provide callback functions to access the needed data (password, groups, object permissions…).
• does NOT do any web-related tasks (forms, views, templates, blueprint, translation…), it just helps providing declarative security layer (role or object permissions) to an HTTP API, well integrated into Flask by extending the existing route decorator.
• does provide a nice integrated parameter management to Flask, including conversions and type checks, detecting missing parameters…
• does care about performance by providing an automatic and relevant caching mechanism to expensive authentication and authorization checks, including relying on external stores such as redis.
• provides simple hooks to extend features, such as adding an password strength checker or a password alternate verifier.
• is much smaller (about 1/10th, ignoring dependencies), so probably it does less things!

Flask-RESTful is a Flask extension designed to ease developping a REST API by associating classes to routes, with class methods to handle each HTTP method. By contrast, Flask Simple Auth:

• does NOT propose/impose a method/class for each route.
• does provide a simpler parameter management scheme.
• integrates cleanly authentification and authorizations, including handling 404 transparently. Our implementation of the doc example is both shorter (32 vs 40 cloc), elegant and more featureful.

TODO

• FSA_PARAM_STYLE any/http/json to restrict/force parameters?
• 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 sloc?
• pypy compatibility? issues with date/time fromisoformat and packages bcrypt, psycopg2, psycopg2cffi, psycopg…
• thread-local stuff in Reference: what about teardown?
• what about asyncio?
• should have explicit tests for psycopg version 2 and 3 drivers
• password re could use a dict for providing an explanation?
• should try to reduce "no cover" pragmas
• coverage should include demo run
• refactor password manager in a separate class?
• allow to restrict allowed group for early typo detection?
• same with oauth scopes?
• add issuer route parameter?
• make oauth and object_perms compatible, if needed?
• document oauth authz in the Authorizations section?
• how to have several issuers and their signatures?