Despite our constant efforts, information beyond this line may not be updated for QGIS 3. Refer to https://qgis.org/pyqgis/master for the python API documentation or, give a hand to update the chapters you know about. Thanks.
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.
Most of the following snippets are derived from the code of Geoserver Explorer plugin and its tests. This is the first plugin that used Authentication infrastructure. The plugin code and its tests can be found at this link. Other good code reference can be read from the authentication infrastructure tests code.
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 master password or by transparently using it to access crypted stored info.
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 = QgsAuthManager.instance() # check if QgsAuthManager has been already 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.authenticationDbPath(): # already initilised => 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 check 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 QGIS API or GUI.
QgsAuthMethodConfig is the base class
for any Authentication Method.
Any Authentication Method sets a configuration hash map where authentication
informations will be stored. Hereafter an useful snippet to store PKI-path
credentials for an hypothetic alice user:
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authMgr = QgsAuthManager.instance() # set alice PKI data p_config = QgsAuthMethodConfig() p_config.setName("alice") p_config.setMethod("PKI-Paths") p_config.setUri("https://example.com") p_config.setConfig("certpath", "path/to/alice-cert.pem" )) p_config.setConfig("keypath", "path/to/alice-key.pem" )) # check if method parameters are correctly set assert p_config.isValid() # register alice data in authdb returning the ``authcfg`` of the stored # configuration authMgr.storeAuthenticationConfig(p_config) newAuthCfgId = p_config.id() assert (newAuthCfgId)
Authentication Methods are loaded dynamically during authentication manager init. The list of Authentication method can vary with QGIS evolution, but the original list of available methods is:
BasicUser and password 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 boundle = QgsPkiBundle.fromPemPaths( "/path/to/alice-cert.pem", "/path/to/alice-key_w-pass.pem", "unlock_pwd", "list_of_CAs_to_bundle" ) assert boundle is not None assert boundle.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 = QgsAuthManager.instance() 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
In : authM = QgsAuthManager.instance() In : authM.authMethod("Identity-Cert").supportedDataProviders() Out: ['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(quri.encodedUri(), '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:
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 to create HTTP connections instead
of integrating with
and its related Authentication Infrastructure integration.
To facilitate this integration an 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` gui = QgsAuthConfigSelect( parent, "postgres" ) # add the above created gui in a new tab of the interface where the # GUI has to be integrated 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:
# create the instance of the QgsAuthEditorWidgets GUI hierarchically linked to # the widget referred with `parent` gui = QgsAuthConfigSelect( parent ) gui.show()
an integrated example can be found in the related test.