add support for AuthFileCredential

sdk/identity/azure-identity/src/main/java/com/azure/identity/AuthFileCredential.java

@@ -0,0 +1,120 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.azure.identity;
+
+import com.azure.core.annotation.Immutable;
+import com.azure.core.credential.AccessToken;
+import com.azure.core.credential.TokenCredential;
+import com.azure.core.credential.TokenRequestContext;
+import com.azure.core.util.serializer.JacksonAdapter;
+import com.azure.core.util.serializer.SerializerAdapter;
+import com.azure.core.util.serializer.SerializerEncoding;
+import com.azure.identity.implementation.IdentityClientOptions;
+import reactor.core.publisher.Mono;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Enables authentication to Azure Active Directory using configuration
+ * information stored Azure SDK Auth File.
+ *
+ * An Azaure SDK Auth file may be generated by passing <code>--sdk-auth</code>
+ * when generating an service principal with
+ * <code>az ad sp create-for-rbac</code>. At this time
+ * <see cref="AuthFileCredential"/> only supports SDK Auth Files which contain a
+ * client secret, client certificates are not supported at this time.
+ */
+@Immutable
+public class AuthFileCredential implements TokenCredential {
+    /* The file path value. */
+    private final String filepath;
+    private  IdentityClientOptions identityClientOptions;
+    private TokenCredential credential;
+    private static final SerializerAdapter SERIALIZER_ADAPTER = JacksonAdapter.createDefaultSerializerAdapter();
+
+    /**
+     *  Creates an instance of the SdkAuthFileCredential class based on information in given SDK Auth file.
+     *  If the file is not found or there are errors parsing it, <see cref="GetToken(TokenRequestContext)"/>
+     *  and <see cref="GetToken(TokenRequestContext)"/> will throw a <see cref="Exception"/>
+     *  with details on why the file could not be used.
+     *
+     * @param filepath The path to the SDK Auth file.
+     * @param identityClientOptions the options for configuring the identity client
+     */
+    AuthFileCredential(String filepath, IdentityClientOptions identityClientOptions) {
+        Objects.requireNonNull(filepath, "'filepath' cannot be null.");
+        Objects.requireNonNull(identityClientOptions, "'identityClientOptions' cannot be null.");
+        this.filepath = filepath;
+        this.identityClientOptions=identityClientOptions;
+    }
+
+    /**
+     * Obtains a token from the Azure Active Directory service, using the specified client detailed specified in the SDK Auth file.
+     * This method is called by Azure SDK clients. It isn't intended for use in application code.  
+     * If the SDK Auth file is missing or invalid, this method throws a <see cref="AuthenticationFailedException"/> exception.
+     * <param name="requestContext">The details of the authentication request</param>
+     * <returns>An <see cref="AccessToken"/> which can be used to authenticate service client calls.</returns>
+     */
+    @Override
+    public Mono<AccessToken> getToken(TokenRequestContext request) {
+        try {
+            ensureCredential();
+        } catch (Exception e) {
+            return Mono.error(e);
+        }
+        return credential.getToken(request);
+    }
+
+    /**  
+     * Ensures that credential information is loaded from the SDK Auth file. This method should be called to initialize
+     * <code>_credential</code> before it is used. If the SDK Auth file is not found or invalid, this method will throw
+     * <see cref="AuthenticationFailedException"/>.
+     * <returns>A method that will ensure <code>credential</code> has been initialized</returns>
+     */
+    private void ensureCredential() throws Exception {
+        if(credential ==null){
+            try
+            {
+                credential = BuildCredentialForCredentialsFile(ParseCredentialsFile(filepath));
+            } catch (Exception e){  
+                throw new Exception("Error parsing SDK Auth File", e);
+            } 
+        }
+    }
+
+    private static Map<String, String> ParseCredentialsFile(String filePath) throws Exception
+    {
+        File file = new File(filePath);
+        if (!file.exists()) {
+            throw new Exception("Auth File doesn't exist");
+        }
+        FileInputStream inputStream = new FileInputStream(file);
+        int length = inputStream.available();
+        byte bytes[] = new byte[length];
+        inputStream.read(bytes);
+        inputStream.close();
+        String result = new String(bytes, StandardCharsets.UTF_8);
+
+		return SERIALIZER_ADAPTER.deserialize(result,Map.class , SerializerEncoding.JSON);
+    }
+
+    private TokenCredential BuildCredentialForCredentialsFile(Map<String, String> authData) throws Exception
+    {
+        String clientId = authData.get("clientId");
+        String clientSecret = authData.get("clientSecret");
+        String tenantId = authData.get("tenantId");
+        String activeDirectoryEndpointUrl = authData.get("activeDirectoryEndpointUrl");
+
+        if (clientId == null || clientSecret == null || tenantId == null || activeDirectoryEndpointUrl == null)
+        {
+            throw new Exception("Malformed Azure SDK Auth file. The file should contain 'clientId', 'clientSecret', 'tenentId' and 'activeDirectoryEndpointUrl' values.");
+        }
+
+        return new ClientSecretCredential(tenantId, clientId, clientSecret, identityClientOptions.setAuthorityHost(activeDirectoryEndpointUrl));
+    }
+}

sdk/identity/azure-identity/src/main/java/com/azure/identity/AuthFileCredentialBuilder.java

@@ -0,0 +1,39 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.azure.identity;
+
+import com.azure.identity.implementation.util.ValidationUtil;
+
+import java.util.HashMap;
+
+/**
+ * Fluent credential builder for instantiating a {@link AuthFileCredential}.
+ *
+ * @see AuthFileCredential
+ */
+public class AuthFileCredentialBuilder extends AadCredentialBuilderBase<AuthFileCredentialBuilder> {
+    private String filepath;
+
+    /**
+     * Sets the file path for the authentication.
+     * @param filepath The path to the SDK Auth file.
+     * @return the AuthFileCredentialBuilder itself
+     */
+    public AuthFileCredentialBuilder filePath(String filepath) {
+        this.filepath = filepath;
+        return this;
+    }
+
+    /**
+     * Creates a new {@link AuthFileCredential} with the current configurations.
+     *
+     * @return a {@link AuthFileCredential} with the current configurations.
+     */
+    public AuthFileCredential build() {
+        ValidationUtil.validate(getClass().getSimpleName(), new HashMap<String, Object>() {{
+                put("filepath", filepath);
+            }});
+        return new AuthFileCredential(filepath, identityClientOptions);
+    }
+}

sdk/identity/azure-identity/src/test/java/com/azure/identity/AuthFileCredentialTests.java

@@ -0,0 +1,36 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.azure.identity;
+
+import com.azure.core.credential.TokenRequestContext;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.powermock.core.classloader.annotations.PowerMockIgnore;
+import org.powermock.core.classloader.annotations.PrepareForTest;
+import org.powermock.modules.junit4.PowerMockRunner;
+
+import reactor.test.StepVerifier;
+
+@RunWith(PowerMockRunner.class)
+@PrepareForTest(fullyQualifiedNames = "com.azure.identity.*")
+@PowerMockIgnore({ "com.sun.org.apache.xerces.*", "javax.xml.*", "org.xml.*" })
+public class AuthFileCredentialTests<T> {
+
+    // @Test
+    // public void SdkAuthFileEnsureCredentialParsesCorrectly() throws Exception {
+        //ClientId,TenantId,ClientSecret in ClientSecretCredential is privated 
+    // }
+
+    @Test
+    public void BadSdkAuthFilePathThrowsDuringGetToken()
+    {
+        TokenRequestContext request = new TokenRequestContext().addScopes("https://management.azure.com");
+
+        // test
+        AuthFileCredential credential =new AuthFileCredentialBuilder().filePath("Bougs*File*Path").build(); 
+        StepVerifier.create(credential.getToken(request))
+            .expectErrorMatches(e -> e instanceof Exception && "Error parsing SDK Auth File".equals(e.getMessage()))
+            .verify();  
+    }
+}