feat(saml): make getting providers from metadata non-panic (#1464)

* feat(saml): make getting providers from metadata non-panic

* show a warning if a provider cannot be fetched by its metadata url
* skip the provider in provisioning state

Closes: #1445

* chore(provider): add provider name to error message

adds the idp config provider name to error message when
the provider host cannot be parsed from metadata url or
fetching metadata document fails.

Closes: #1445

---------

Co-authored-by: Stefan Jacobi <stefan.jacobi@adesso.de>

backend/ee/saml/handler.go

@@ -33,15 +33,17 @@ func NewSamlHandler(cfg *config.Config, persister persistence.Persister, session
 	providers := make([]provider.ServiceProvider, 0)
 	for _, idpConfig := range cfg.Saml.IdentityProviders {
 		if idpConfig.Enabled {
-			name := ""
-			name, err := parseProviderFromMetadataUrl(idpConfig.MetadataUrl)
+			hostName := ""
+			hostName, err := parseProviderFromMetadataUrl(idpConfig.MetadataUrl)
 			if err != nil {
-				panic(err)
+				fmt.Printf("failed to parse provider '%s' from metadata url: %v\n", idpConfig.Name, err)
+				continue
 			}
 
-			newProvider, err := provider.GetProvider(name, cfg, idpConfig, persister.GetSamlCertificatePersister())
+			newProvider, err := provider.GetProvider(hostName, cfg, idpConfig, persister.GetSamlCertificatePersister())
 			if err != nil {
-				panic(err)
+				fmt.Printf("failed to initialize provider '%s': %v\n", idpConfig.Name, err)
+				continue
 			}
 
 			providers = append(providers, newProvider)