func()

in xds/resolver/xds_resolver.go [79:160]

• 65 lines of code
• 14 McCabe index (conditional complexity)

func (b *xdsResolverBuilder) Build(t resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (_ resolver.Resolver, retErr error) {
	r := &xdsResolver{
		target:         t,
		cc:             cc,
		closed:         grpcsync.NewEvent(),
		updateCh:       make(chan suWithError, 1),
		activeClusters: make(map[string]*clusterInfo),
	}
	defer func() {
		if retErr != nil {
			r.Close()
		}
	}()
	r.logger = dubbogoLogger.GetLogger()
	r.logger.Infof("Creating resolver for target: %+v", t)

	newXDSClient := newXDSClient
	if b.newXDSClient != nil {
		newXDSClient = b.newXDSClient
	}

	client, err := newXDSClient()
	if err != nil {
		return nil, fmt.Errorf("xds: failed to create xds-client: %v", err)
	}
	r.client = client
	bootstrapConfig := client.BootstrapConfig()
	if bootstrapConfig == nil {
		return nil, errors.New("bootstrap configuration is empty")
	}

	// If xds credentials were specified by the user, but bootstrap configs do
	// not contain any certificate provider configuration, it is better to fail
	// right now rather than failing when attempting to create certificate
	// providers after receiving an CDS response with security configuration.
	var creds credentials.TransportCredentials
	switch {
	case opts.DialCreds != nil:
		creds = opts.DialCreds
	case opts.CredsBundle != nil:
		creds = opts.CredsBundle.TransportCredentials()
	}
	if xc, ok := creds.(interface{ UsesXDS() bool }); ok && xc.UsesXDS() {
		if len(bootstrapConfig.CertProviderConfigs) == 0 {
			return nil, errors.New("xds: xdsCreds specified but certificate_providers config missing in bootstrap file")
		}
	}

	// Find the client listener template to use from the bootstrap config:
	// - If authority is not set in the target, use the top level template
	// - If authority is set, use the template from the authority map.
	template := bootstrapConfig.ClientDefaultListenerResourceNameTemplate
	if authority := r.target.URL.Host; authority != "" {
		a := bootstrapConfig.Authorities[authority]
		if a == nil {
			return nil, fmt.Errorf("xds: authority %q is not found in the bootstrap file", authority)
		}
		if a.ClientListenerResourceNameTemplate != "" {
			// This check will never be false, because
			// ClientListenerResourceNameTemplate is required to start with
			// xdstp://, and has a default value (not an empty string) if unset.
			template = a.ClientListenerResourceNameTemplate
		}
	}
	endpoint := r.target.URL.Path
	if endpoint == "" {
		endpoint = r.target.URL.Opaque
	}
	endpoint = strings.TrimPrefix(endpoint, "/")
	resourceName := bootstrap.PopulateResourceTemplate(template, endpoint)

	// Register a watch on the xdsClient for the user's dial target.
	cancelWatch := watchService(r.client, resourceName, r.handleServiceUpdate, r.logger)
	r.logger.Infof("Watch started on resource name %v with xds-client %p", r.target.Endpoint, r.client)
	r.cancelWatch = func() {
		cancelWatch()
		r.logger.Infof("Watch cancel on resource name %v with xds-client %p", r.target.Endpoint, r.client)
	}

	go r.run()
	return r, nil
}