[GitHub] [nifi] adenes commented on a change in pull request #5319: NIFI-9065 Add support for OAuth2AccessTokenProvider in InvokeHTTP.

[GitBox <gi...@apache.org>]

adenes commented on a change in pull request #5319:
URL: https://github.com/apache/nifi/pull/5319#discussion_r702769722



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File path: nifi-nar-bundles/nifi-standard-services/nifi-oauth2-provider-bundle/nifi-oauth2-provider-service/src/main/java/org/apache/nifi/oauth2/StandardOauth2AccessTokenProvider.java
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@@ -0,0 +1,300 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.nifi.oauth2;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import okhttp3.FormBody;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnDisabled;
+import org.apache.nifi.annotation.lifecycle.OnEnabled;
+import org.apache.nifi.components.AllowableValue;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.controller.AbstractControllerService;
+import org.apache.nifi.controller.ConfigurationContext;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.ssl.SSLContextService;
+
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.X509TrustManager;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+@Tags({"oauth2", "provider", "authorization", "access token", "http"})
+@CapabilityDescription("Provides OAuth 2.0 access tokens that can be used as Bearer authorization header in HTTP requests." +
+    " Uses Resource Owner Password Credentials Grant.")
+public class StandardOauth2AccessTokenProvider extends AbstractControllerService implements OAuth2AccessTokenProvider {
+    public static final PropertyDescriptor AUTHORIZATION_SERVER_URL = new PropertyDescriptor.Builder()
+        .name("authorization-server-url")
+        .displayName("Authorization Server URL")
+        .description("The URL of the authorization server that issues access tokens.")
+        .required(true)
+        .addValidator(StandardValidators.URL_VALIDATOR)
+        .expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+        .build();
+
+    public static AllowableValue RESOURCE_OWNER_PASSWORD_CREDENTIALS_GRANT_TYPE = new AllowableValue(
+        "password",
+        "User Password",
+        "Resource Owner Password Credentials Grant. Used to access resources available to users. Requires username and password and usually Client ID and Client Secret"
+    );
+    public static AllowableValue CLIENT_CREDENTIALS_GRANT_TYPE = new AllowableValue(
+        "client_credentials",
+        "Client Credentials",
+        "Client Credentials Grant. Used to access resources available to clients. Requires Client ID and Client Secret"
+    );
+
+    public static final PropertyDescriptor GRANT_TYPE = new PropertyDescriptor.Builder()
+        .name("grant-type")
+        .displayName("Grant Type")
+        .description("The OAuth2 Grant Type to be used when acquiring an access token.")
+        .required(true)
+        .allowableValues(RESOURCE_OWNER_PASSWORD_CREDENTIALS_GRANT_TYPE, CLIENT_CREDENTIALS_GRANT_TYPE)
+        .defaultValue(RESOURCE_OWNER_PASSWORD_CREDENTIALS_GRANT_TYPE.getValue())
+        .build();
+
+    public static final PropertyDescriptor USERNAME = new PropertyDescriptor.Builder()
+        .name("service-user-name")
+        .displayName("Username")
+        .description("Username on the service that is being accessed.")
+        .dependsOn(GRANT_TYPE, RESOURCE_OWNER_PASSWORD_CREDENTIALS_GRANT_TYPE)
+        .required(true)
+        .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+        .expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+        .build();
+
+    public static final PropertyDescriptor PASSWORD = new PropertyDescriptor.Builder()
+        .name("service-password")
+        .displayName("Password")
+        .description("Password for the username on the service that is being accessed.")
+        .dependsOn(GRANT_TYPE, RESOURCE_OWNER_PASSWORD_CREDENTIALS_GRANT_TYPE)
+        .required(true)
+        .sensitive(true)
+        .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+        .build();
+
+    public static final PropertyDescriptor CLIENT_ID = new PropertyDescriptor.Builder()
+        .name("client-id")
+        .displayName("Client ID")
+        .required(false)
+        .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+        .expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+        .build();
+
+    public static final PropertyDescriptor CLIENT_SECRET = new PropertyDescriptor.Builder()
+        .name("client-secret")
+        .displayName("Client secret")
+        .dependsOn(CLIENT_ID)
+        .required(true)
+        .sensitive(true)
+        .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+        .build();
+
+    public static final PropertyDescriptor SSL_CONTEXT = new PropertyDescriptor.Builder()
+        .name("ssl-context")
+        .displayName("SSL Context")
+        .addValidator(Validator.VALID)
+        .identifiesControllerService(SSLContextService.class)
+        .required(false)
+        .build();
+
+    private static final List<PropertyDescriptor> PROPERTIES = Collections.unmodifiableList(Arrays.asList(
+        AUTHORIZATION_SERVER_URL,
+        GRANT_TYPE,
+        USERNAME,
+        PASSWORD,
+        CLIENT_ID,
+        CLIENT_SECRET,
+        SSL_CONTEXT
+    ));
+
+    public static final ObjectMapper ACCESS_DETAILS_MAPPER = new ObjectMapper()
+        .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
+        .setPropertyNamingStrategy(PropertyNamingStrategies.SNAKE_CASE);
+
+    private volatile String authorizationServerUrl;
+    private volatile OkHttpClient httpClient;
+
+    private volatile String grantType;
+    private volatile String username;
+    private volatile String password;
+    private volatile String clientId;
+    private volatile String clientSecret;
+
+    private volatile AccessToken accessDetails;
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return PROPERTIES;
+    }
+
+    @OnEnabled
+    public void onEnabled(ConfigurationContext context) {
+        authorizationServerUrl = context.getProperty(AUTHORIZATION_SERVER_URL).evaluateAttributeExpressions().getValue();
+
+        httpClient = createHttpClient(context);
+
+        grantType = context.getProperty(GRANT_TYPE).getValue();
+        username = context.getProperty(USERNAME).evaluateAttributeExpressions().getValue();
+        password = context.getProperty(PASSWORD).getValue();
+        clientId = context.getProperty(CLIENT_ID).evaluateAttributeExpressions().getValue();
+        clientSecret = context.getProperty(CLIENT_SECRET).getValue();
+    }
+
+    @OnDisabled
+    public void onDisabled() {
+        accessDetails = null;
+    }
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext validationContext) {
+        final List<ValidationResult> validationResults = new ArrayList<>(super.customValidate(validationContext));
+
+        if (
+            validationContext.getProperty(GRANT_TYPE).getValue().equals(CLIENT_CREDENTIALS_GRANT_TYPE.getValue())
+                && !validationContext.getProperty(CLIENT_ID).isSet()
+        ) {
+            validationResults.add(new ValidationResult.Builder().subject(CLIENT_ID.getDisplayName())
+                .valid(false)
+                .explanation(String.format(
+                    "When '%s' is set to '%s', '%s' is required",
+                    GRANT_TYPE.getDisplayName(),
+                    CLIENT_CREDENTIALS_GRANT_TYPE.getDisplayName(),
+                    CLIENT_ID.getDisplayName())
+                )
+                .build());
+        }
+
+        return validationResults;
+    }
+
+    protected OkHttpClient createHttpClient(ConfigurationContext context) {
+        OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder();
+
+        SSLContextService sslService = context.getProperty(SSL_CONTEXT).asControllerService(SSLContextService.class);
+        if (sslService != null) {
+            final X509TrustManager trustManager = sslService.createTrustManager();
+            SSLContext sslContext = sslService.createContext();
+            clientBuilder.sslSocketFactory(sslContext.getSocketFactory(), trustManager);
+        }
+
+        return clientBuilder.build();
+    }
+
+    @Override
+    public AccessToken getAccessDetails() {
+        if (this.accessDetails == null) {
+            acquireAccessDetails();
+        } else if (this.accessDetails.isExpired()) {
+            if (this.accessDetails.getRefreshToken() == null) {
+                acquireAccessDetails();
+            } else {
+                try {
+                    refreshAccessDetails();
+                } catch (Exception e) {
+                    getLogger().info("Couldn't refresh access token.", e);

Review comment:
       @exceptionfactory , although I don't have a strong opinion on this particular point my concern with `null`ing the `accessDetails` is that it might be a bit confusing to the reader and we don't save too much here:
   - if there'll be multiple calls to this method and the refresh-acquire pair fails then there's some bigger problem -> the "extra" refresh try doesn't make too much difference.
   - But if the subsequent call succeeds at `acquireAccessDetails` then we only have one unnecessary refresh call.
   
   Compared to how confusing the `accessDetails = null` could be it might not be worth it.
   WDYT?




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