xds: 1st part of implementation of CertificateProvider for agentless (#7170)

xds/src/main/java/io/grpc/xds/internal/certprovider/CertificateProvider.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2020 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.xds.internal.certprovider;
+
+import java.io.Closeable;
+import java.security.PrivateKey;
+import java.security.cert.X509Certificate;
+import java.util.List;
+
+/**
+ * A plug-in that provides certificates required by the xDS security component and created
+ * using the certificate-provider config from the xDS server.
+ *
+ * <p>We may move this out of the internal package and make this an official API in the future.
+ *
+ * <p>The plugin fetches certificates - root and optionally identity cert - required by xDS
+ * security.
+ */
+public abstract class CertificateProvider implements Closeable {
+
+  /** A watcher is registered via the constructor to receive updates for the certificates. */
+  public interface Watcher {
+    void updateCertificate(PrivateKey key, List<X509Certificate> certChain);
+
+    void updateTrustedRoots(List<X509Certificate> trustedRoots);
+
+    void onError(io.grpc.Status errorStatus);
+  }
+
+  /**
+   * Concrete subclasses will call this to register the {@link Watcher}.
+   *
+   * @param watcher to register
+   * @param notifyCertUpdates if true, the provider is required to call the watcher’s
+   *     updateCertificate method. Implies the Provider is capable of minting certificates.
+   *     Used by server-side and mTLS client-side. Note the Provider is always required
+   *     to call updateTrustedRoots to provide trusted-root updates.
+   */
+  protected CertificateProvider(Watcher watcher, boolean notifyCertUpdates) {
+    this.watcher = watcher;
+    this.notifyCertUpdates = notifyCertUpdates;
+  }
+
+  /** Releases all resources and stop cert refreshes and watcher updates. */
+  @Override
+  public abstract void close();
+
+  protected final Watcher watcher;
+  protected final boolean notifyCertUpdates;
+}

xds/src/main/java/io/grpc/xds/internal/certprovider/CertificateProviderProvider.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2020 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.xds.internal.certprovider;
+
+import io.grpc.xds.internal.certprovider.CertificateProvider.Watcher;
+
+/**
+ * Provider of {@link CertificateProvider}s. Implemented by the implementer of the plugin. We may
+ * move this out of the internal package and make this an official API in the future.
+ */
+interface CertificateProviderProvider {
+  /** Returns the unique name of the {@link CertificateProvider} plugin. */
+  String getName();
+
+  /**
+   * Creates a {@link CertificateProvider} plugin.
+   *
+   * @param config configuration needed by the Provider to create the CertificateProvider. A form of
+   *     JSON that the Provider understands e.g. a string or a key-value Map.
+   * @param watcher A {@link Watcher} to receive updates from the CertificateProvider
+   * @param notifyCertUpdates See {@link CertificateProvider#CertificateProvider(Watcher, boolean)}
+   */
+  CertificateProvider createCertificateProvider(
+      Object config, Watcher watcher, boolean notifyCertUpdates) throws IllegalArgumentException;
+}