14. Authentication infrastructure¶
The code snippets on this page need the following imports if you’re outside the pyqgis console:
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from qgis.core import ( QgsApplication, QgsRasterLayer, QgsAuthMethodConfig, QgsDataSourceUri, QgsPkiBundle, QgsMessageLog, ) from qgis.gui import ( QgsAuthAuthoritiesEditor, QgsAuthConfigEditor, QgsAuthConfigSelect, QgsAuthSettingsWidget, ) from qgis.PyQt.QtWidgets import ( QWidget, QTabWidget, ) from qgis.PyQt.QtNetwork import QSslCertificate
User reference of the Authentication infrastructure can be read in the User Manual in the Authentication System Overview paragraph.
This chapter describes the best practices to use the Authentication system from a developer perspective.
The authentication system is widely used in QGIS Desktop by data providers whenever credentials are required to access a particular resource, for example when a layer establishes a connection to a Postgres database.
There are also a few widgets in the QGIS gui library that plugin developers can use to easily integrate the authentication infrastructure into their code:
A good code reference can be read from the authentication infrastructure tests code.
Due to the security constraints that were taken into account during the authentication infrastructure design, only a selected subset of the internal methods are exposed to Python.
Here are some definition of the most common objects treated in this chapter.
- Master Password
Password to allow access and decrypt credential stored in the QGIS Authentication DB
- Authentication Database
- Authentication DB
- Authentication Configuration
A set of authentication data depending on Authentication Method. e.g Basic authentication method stores the couple of user/password.
- Authentication Config
- Authentication Method
A specific method used to get authenticated. Each method has its own protocol used to gain the authenticated level. Each method is implemented as shared library loaded dynamically during QGIS authentication infrastructure init.
This class takes care of the user interaction: by asking to set a master password or by transparently using it to access encrypted stored information.
The following snippet gives an example to set master password to open the access to the authentication settings. Code comments are important to understand the snippet.
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authMgr = QgsApplication.authManager() # check if QgsAuthManager has already been initialized... a side effect # of the QgsAuthManager.init() is that AuthDbPath is set. # QgsAuthManager.init() is executed during QGIS application init and hence # you do not normally need to call it directly. if authMgr.authenticationDatabasePath(): # already initialized => we are inside a QGIS app. if authMgr.masterPasswordIsSet(): msg = 'Authentication master password not recognized' assert authMgr.masterPasswordSame("your master password"), msg else: msg = 'Master password could not be set' # The verify parameter checks if the hash of the password was # already saved in the authentication db assert authMgr.setMasterPassword("your master password", verify=True), msg else: # outside qgis, e.g. in a testing environment => setup env var before # db init os.environ['QGIS_AUTH_DB_DIR_PATH'] = "/path/where/located/qgis-auth.db" msg = 'Master password could not be set' assert authMgr.setMasterPassword("your master password", True), msg authMgr.init("/path/where/located/qgis-auth.db")
authcfg = 'fm1s770'
that string is generated automatically when creating an entry using the QGIS API or GUI, but it might be useful to manually set it to a known value in case the configuration must be shared (with different credentials) between multiple users within an organization.
QgsAuthMethodConfig is the base class
for any Authentication Method.
Any Authentication Method sets a configuration hash map where authentication
information will be stored. Hereafter a useful snippet to store PKI-path
credentials for a hypothetical alice user:
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authMgr = QgsApplication.authManager() # set alice PKI data config = QgsAuthMethodConfig() config.setName("alice") config.setMethod("PKI-Paths") config.setUri("https://example.com") config.setConfig("certpath", "path/to/alice-cert.pem" ) config.setConfig("keypath", "path/to/alice-key.pem" ) # check if method parameters are correctly set assert config.isValid() # register alice data in authdb returning the ``authcfg`` of the stored # configuration authMgr.storeAuthenticationConfig(config) newAuthCfgId = config.id() assert newAuthCfgId
Authentication Method libraries are loaded dynamically during authentication manager init. Available authentication methods are:
BasicUser and password authentication
Esri-TokenESRI token based authentication
Identity-CertIdentity certificate authentication
PKI-PathsPKI paths authentication
PKI-PKCS#12PKI PKCS#12 authentication
A convenience class to pack PKI bundles composed on SslCert, SslKey and CA
chain is the
class. Hereafter a snippet to get password protected:
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# add alice cert in case of key with pwd caBundlesList =  # List of CA bundles bundle = QgsPkiBundle.fromPemPaths( "/path/to/alice-cert.pem", "/path/to/alice-key_w-pass.pem", "unlock_pwd", caBundlesList ) assert bundle is not None # You can check bundle validity by calling: # bundle.isValid()
QgsPkiBundle class documentation
to extract cert/key/CAs from the bundle.
We can remove an entry from Authentication Database using it’s
authcfg identifier with the following snippet:
authMgr = QgsApplication.authManager() authMgr.removeAuthenticationConfig( "authCfg_Id_to_remove" )
The best way to use an Authentication Config stored in the
Authentication DB is referring it with the unique identifier
authcfg. Expanding, means convert it from an identifier to a complete
set of credentials.
The best practice to use stored Authentication Configs, is to leave it
managed automatically by the Authentication manager.
The common use of a stored configuration is to connect to an authentication
enabled service like a WMS or WFS or to a DB connection.
Take into account that not all QGIS data providers are integrated with the
Authentication infrastructure. Each authentication method, derived from the
and support a different set of Providers. For example the
certIdentity() method supports the following list
authM = QgsApplication.authManager() print(authM.authMethod("Identity-Cert").supportedDataProviders())
['ows', 'wfs', 'wcs', 'wms', 'postgres']
For example, to access a WMS service using stored credentials identified with
authcfg = 'fm1s770', we just have to use the
authcfg in the data source
URL like in the following snippet:
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authCfg = 'fm1s770' quri = QgsDataSourceUri() quri.setParam("layers", 'usa:states') quri.setParam("styles", '') quri.setParam("format", 'image/png') quri.setParam("crs", 'EPSG:4326') quri.setParam("dpiMode", '7') quri.setParam("featureCount", '10') quri.setParam("authcfg", authCfg) # <---- here my authCfg url parameter quri.setParam("contextualWMSLegend", '0') quri.setParam("url", 'https://my_auth_enabled_server_ip/wms') rlayer = QgsRasterLayer(str(quri.encodedUri(), "utf-8"), 'states', 'wms')
In the upper case, the
wms provider will take care to expand
URI parameter with credential just before setting the HTTP connection.
The developer would have to leave
authcfg expansion to the
QgsAuthManager, in this way he will be sure that expansion is not done too early.
Usually an URI string, built using the
class, is used to set a data source in the following way:
authCfg = 'fm1s770' quri = QgsDataSourceUri("my WMS uri here") quri.setParam("authcfg", authCfg) rlayer = QgsRasterLayer( quri.uri(False), 'states', 'wms')
False parameter is important to avoid URI complete expansion of the
authcfg id present in the URI.
Many third party plugins are using httplib2 or other Python networking libraries to manage HTTP
connections instead of integrating with
and its related Authentication Infrastructure integration.
To facilitate this integration a helper Python function has been created
NetworkAccessManager. Its code can be found here.
This helper class can be used as in the following snippet:
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http = NetworkAccessManager(authid="my_authCfg", exception_class=My_FailedRequestError) try: response, content = http.request( "my_rest_url" ) except My_FailedRequestError, e: # Handle exception pass
In this paragraph are listed the available GUIs useful to integrate authentication infrastructure in custom interfaces.
and can be used as in the following snippet:
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# create the instance of the QgsAuthConfigSelect GUI hierarchically linked to # the widget referred with `parent` parent = QWidget() # Your GUI parent widget gui = QgsAuthConfigSelect( parent, "postgres" ) # add the above created gui in a new tab of the interface where the # GUI has to be integrated tabGui = QTabWidget() tabGui.insertTab( 1, gui, "Configurations" )
The above example is taken from the QGIS source code. The second parameter of the GUI constructor refers to data provider type. The parameter is used to restrict the compatible Authentication Methods with the specified provider.
The complete GUI used to manage credentials, authorities and to access to
Authentication utilities is managed by the
and can be used as in the following snippet:
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# create the instance of the QgsAuthEditorWidgets GUI hierarchically linked to # the widget referred with `parent` parent = QWidget() # Your GUI parent widget gui = QgsAuthConfigSelect( parent ) gui.show()
An integrated example can be found in the related test.