Affected Issue(s): Extend OAuth 2.0 support

Resolves sid-indonesia/it-team#333

What this commit has achieved:
1. Added support for Body Authentication on Client Credentials flow
2. TODO implement OAuth 2.0 for sink FHIR Server.

Author: muhammad-levi

pipelines/batch/src/main/java/com/google/fhir/analytics/FhirEtlOptions.java

@@ -15,6 +15,7 @@
  */
 package com.google.fhir.analytics;
 
+import com.google.fhir.analytics.enumeration.ClientCredentialsAuthMechanism;
 import org.apache.beam.sdk.options.Default;
 import org.apache.beam.sdk.options.Description;
 import org.apache.beam.sdk.options.Validation.Required;
@@ -84,6 +85,12 @@ public interface FhirEtlOptions extends BasePipelineOptions {
 
   void setFhirServerOAuthTokenEndpoint(String value);
 
+  @Description("The mechanism for authenticating a client in the Client Credentials flow.")
+  @Default.Enum("BASIC")
+  ClientCredentialsAuthMechanism getFhirServerOAuthMechanism();
+
+  void setFhirServerOAuthMechanism(ClientCredentialsAuthMechanism value);
+
   @Description(
       "The `client_id` to be used in the OAuth Client Credential flow when interacting with the "
           + "FHIR server; see `fhirServerOAuthEndpoint`.")

pipelines/common/src/main/java/com/google/fhir/analytics/FetchUtil.java

@@ -31,13 +31,15 @@
 import ca.uhn.fhir.rest.gclient.IOperationUntyped;
 import ca.uhn.fhir.rest.gclient.IOperationUntypedWithInput;
 import com.google.api.client.auth.oauth2.ClientCredentialsTokenRequest;
+import com.google.api.client.auth.oauth2.ClientParametersAuthentication;
 import com.google.api.client.auth.oauth2.TokenResponse;
 import com.google.api.client.http.BasicAuthentication;
 import com.google.api.client.http.GenericUrl;
 import com.google.api.client.http.javanet.NetHttpTransport;
 import com.google.api.client.json.gson.GsonFactory;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
+import com.google.fhir.analytics.enumeration.ClientCredentialsAuthMechanism;
 import java.io.IOException;
 import java.time.Instant;
 import java.util.List;
@@ -61,6 +63,8 @@ public class FetchUtil {
 
   private final String oAuthTokenEndpoint;
 
+  private final ClientCredentialsAuthMechanism oAuthMechanism;
+
   private final String oAuthClientId;
 
   private final String oAuthClientSecret;
@@ -74,13 +78,15 @@ public class FetchUtil {
       String sourceUser,
       String sourcePw,
       String oAuthTokenEndpoint,
+      ClientCredentialsAuthMechanism oAuthMechanism,
       String oAuthClientId,
       String oAuthClientSecret,
       FhirContext fhirContext) {
     this.fhirUrl = sourceFhirUrl;
     this.sourceUser = Strings.nullToEmpty(sourceUser);
     this.sourcePw = Strings.nullToEmpty(sourcePw);
     this.oAuthTokenEndpoint = Strings.nullToEmpty(oAuthTokenEndpoint);
+    this.oAuthMechanism = oAuthMechanism;
     this.oAuthClientId = Strings.nullToEmpty(oAuthClientId);
     this.oAuthClientSecret = Strings.nullToEmpty(oAuthClientSecret);
     this.fhirContext = fhirContext;
@@ -93,7 +99,7 @@ public class FetchUtil {
       log.info("Fetching access tokens from {}", oAuthTokenEndpoint);
       authInterceptor =
           new ClientCredentialsAuthInterceptor(
-              oAuthTokenEndpoint, oAuthClientId, oAuthClientSecret);
+              oAuthTokenEndpoint, oAuthMechanism, oAuthClientId, oAuthClientSecret);
     } else if (!this.sourceUser.isEmpty()) {
       authInterceptor = new BasicAuthInterceptor(this.sourceUser, sourcePw);
     } else {
@@ -252,16 +258,23 @@ private static class ClientCredentialsAuthInterceptor extends BearerTokenAuthInt
     private static final int TOKEN_REFRESH_LEEWAY_IN_SECONDS = 10;
 
     private final String tokenEndpoint;
+    private final ClientCredentialsAuthMechanism oAuthMechanism;
     private final String clientId;
     private final String clientSecret;
     private TokenResponse tokenResponse;
     private Instant nextRefresh;
 
-    ClientCredentialsAuthInterceptor(String tokenEndpoint, String clientId, String clientSecret) {
+    ClientCredentialsAuthInterceptor(
+        String tokenEndpoint,
+        ClientCredentialsAuthMechanism oAuthMechanism,
+        String clientId,
+        String clientSecret) {
       Preconditions.checkNotNull(tokenEndpoint);
+      Preconditions.checkNotNull(clientSecret);
       Preconditions.checkNotNull(clientId);
       Preconditions.checkNotNull(clientSecret);
       this.tokenEndpoint = tokenEndpoint;
+      this.oAuthMechanism = oAuthMechanism;
       this.clientId = clientId;
       this.clientSecret = clientSecret;
     }
@@ -291,12 +304,24 @@ public void interceptRequest(IHttpRequest theRequest) {
     }
 
     TokenResponse requestAccessToken() throws IOException {
-      TokenResponse response =
+      ClientCredentialsTokenRequest clientCredentialsTokenRequest =
           new ClientCredentialsTokenRequest(
-                  new NetHttpTransport(), new GsonFactory(), new GenericUrl(tokenEndpoint))
-              .setClientAuthentication(new BasicAuthentication(clientId, clientSecret))
-              .execute();
-      return response;
+              new NetHttpTransport(), new GsonFactory(), new GenericUrl(tokenEndpoint));
+      switch (oAuthMechanism) {
+        case BASIC:
+          clientCredentialsTokenRequest =
+              clientCredentialsTokenRequest.setClientAuthentication(
+                  new BasicAuthentication(clientId, clientSecret));
+          break;
+        case BODY:
+          clientCredentialsTokenRequest =
+              clientCredentialsTokenRequest.setClientAuthentication(
+                  new ClientParametersAuthentication(clientId, clientSecret));
+          break;
+        case JWT:
+          break;
+      }
+      return clientCredentialsTokenRequest.execute();
     }
   }
 }

pipelines/common/src/main/java/com/google/fhir/analytics/enumeration/ClientCredentialsAuthMechanism.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2020-2024 Google LLC
+ *
+ * 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 com.google.fhir.analytics.enumeration;
+
+/**
+ * A set of enumerations to specify the mechanism for authenticating a client in the Client
+ * Credentials flow.
+ */
+public enum ClientCredentialsAuthMechanism {
+  /**
+   * the client sends its client ID and client secret as part of the Authorization header in an HTTP
+   * request. The Authorization header contains a Base64-encoded string of <code>
+   * {URL-encoded-client-ID}:{URL-encoded-client-secret}</code>
+   */
+  BASIC,
+
+  /**
+   * The client sends its client ID and client secret as parameters in the body of the HTTP request.
+   * This is similar to Basic Authentication, but instead of sending the credentials in the
+   * Authorization header, they are sent in the request body.
+   */
+  BODY,
+
+  /** TODO: Unimplemented yet, as the need for it has not arisen. */
+  JWT
+}

pipelines/controller/src/main/java/com/google/fhir/analytics/ControlPanelApplication.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2023 Google LLC
+ * Copyright 2020-2024 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

pipelines/controller/src/main/java/com/google/fhir/analytics/PipelineManager.java

@@ -331,6 +331,7 @@ private FhirSearchUtil getFhirSearchUtil(FhirEtlOptions options) {
             options.getFhirServerUserName(),
             options.getFhirServerPassword(),
             options.getFhirServerOAuthTokenEndpoint(),
+            options.getFhirServerOAuthMechanism(),
             options.getFhirServerOAuthClientId(),
             options.getFhirServerOAuthClientSecret(),
             avroConversionUtil.getFhirContext()));