Channel Builders

/**
 * ALTS version of ManagedChannelBuilder that sets up secure and authenticated
 * communication between two cloud VMs using ALTS.
 */
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/4151")
public final class AltsChannelBuilder extends ForwardingChannelBuilder2<AltsChannelBuilder> {
    
    /**
     * Creates an ALTS channel builder for the given target
     * @param target the target URI or authority to connect to
     * @return AltsChannelBuilder instance
     */
    public static AltsChannelBuilder forTarget(String target);
    
    /**
     * Creates an ALTS channel builder for the given address and port
     * @param name the hostname or IP address
     * @param port the port number
     * @return AltsChannelBuilder instance
     */
    public static AltsChannelBuilder forAddress(String name, int port);
    
    /**
     * Adds an expected target service account. One of the added service accounts
     * should match the peer service account in the handshaker result.
     * @param targetServiceAccount the expected target service account
     * @return this builder for chaining
     */
    public AltsChannelBuilder addTargetServiceAccount(String targetServiceAccount);
    
    /**
     * Enables untrusted ALTS for testing. Disables Google Cloud Platform checks.
     * @return this builder for chaining
     */
    public AltsChannelBuilder enableUntrustedAltsForTesting();
    
    /**
     * Sets a custom handshaker service address for testing
     * @param handshakerAddress the handshaker service address
     * @return this builder for chaining
     */
    public AltsChannelBuilder setHandshakerAddressForTesting(String handshakerAddress);
    
    /**
     * Builds the managed channel with ALTS security
     * @return the configured ManagedChannel
     */
    public ManagedChannel build();
}

import io.grpc.alts.AltsChannelBuilder;
import io.grpc.ManagedChannel;

// Basic ALTS channel
ManagedChannel channel = AltsChannelBuilder
    .forTarget("my-service:443")
    .build();

// ALTS channel with service account verification
ManagedChannel secureChannel = AltsChannelBuilder
    .forAddress("10.0.0.1", 8080)
    .addTargetServiceAccount("backend@my-project.iam.gserviceaccount.com")
    .addTargetServiceAccount("backup@my-project.iam.gserviceaccount.com")
    .build();

// Testing configuration
ManagedChannel testChannel = AltsChannelBuilder
    .forTarget("localhost:8080")
    .enableUntrustedAltsForTesting()
    .setHandshakerAddressForTesting("localhost:9999")
    .build();

/**
 * Channel builder that automatically chooses ALTS on GCP and TLS elsewhere
 */
public final class ComputeEngineChannelBuilder extends ForwardingChannelBuilder<ComputeEngineChannelBuilder> {
    
    /**
     * Creates a Compute Engine channel builder for the given target
     * @param target the target URI or authority to connect to
     * @return ComputeEngineChannelBuilder instance
     */
    public static ComputeEngineChannelBuilder forTarget(String target);
    
    /**
     * Creates a Compute Engine channel builder for the given address and port
     * @param name the hostname or IP address
     * @param port the port number
     * @return ComputeEngineChannelBuilder instance
     */
    public static ComputeEngineChannelBuilder forAddress(String name, int port);
}

import io.grpc.alts.ComputeEngineChannelBuilder;
import io.grpc.ManagedChannel;

// Automatic ALTS/TLS selection based on environment
ManagedChannel channel = ComputeEngineChannelBuilder
    .forTarget("my-service.googleapis.com:443")
    .build();

// Uses ALTS on GCP, TLS elsewhere
ManagedChannel flexibleChannel = ComputeEngineChannelBuilder
    .forAddress("backend-service", 8080)
    .build();

/**
 * Channel builder for Google Cloud services with full authentication support
 */
public final class GoogleDefaultChannelBuilder extends ForwardingChannelBuilder<GoogleDefaultChannelBuilder> {
    
    /**
     * Creates a Google Default channel builder for the given target
     * @param target the target URI or authority to connect to
     * @return GoogleDefaultChannelBuilder instance
     */
    public static GoogleDefaultChannelBuilder forTarget(String target);
    
    /**
     * Creates a Google Default channel builder for the given address and port
     * @param name the hostname or IP address
     * @param port the port number
     * @return GoogleDefaultChannelBuilder instance
     */
    public static GoogleDefaultChannelBuilder forAddress(String name, int port);
}

import io.grpc.alts.GoogleDefaultChannelBuilder;
import io.grpc.ManagedChannel;

// Full Google Cloud authentication
ManagedChannel channel = GoogleDefaultChannelBuilder
    .forTarget("pubsub.googleapis.com:443")
    .build();

// Works with Google Cloud APIs
ManagedChannel apiChannel = GoogleDefaultChannelBuilder
    .forTarget("storage.googleapis.com:443")
    .build();