update EnvironmentCredential and azure.core.util.Configuration

sdk/core/azure-core/src/main/java/com/azure/core/util/Configuration.java

@@ -75,6 +75,11 @@ public class Configuration implements Cloneable {
      */
     public static final String PROPERTY_AZURE_TENANT_ID = "AZURE_TENANT_ID";
 
+    /**
+     * Path of a PEM certificate file to use when performing service principal authentication with Azure.
+     */
+    public static final String PROPERTY_AZURE_CLIENT_CERTIFICATE_PATH = "AZURE_CLIENT_CERTIFICATE_PATH";
+
     /**
      * Name of the Azure resource group.
      */

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

@@ -14,14 +14,28 @@
 import reactor.core.publisher.Mono;
 
 /**
- * A credential provider that provides token credentials based on environment variables.  The environment variables
+ * A credential provider that provides token credentials based on environment variables.  The sets of environment variables
  * expected are:
  * <p>
  * <ul>
  *     <li>{@link Configuration#PROPERTY_AZURE_CLIENT_ID AZURE_CLIENT_ID}</li>
  *     <li>{@link Configuration#PROPERTY_AZURE_CLIENT_SECRET AZURE_CLIENT_SECRET}</li>
  *     <li>{@link Configuration#PROPERTY_AZURE_TENANT_ID AZURE_TENANT_ID}</li>
  * </ul>
+ * or:
+ * <p>
+ * <ul>
+ *     <li>{@link Configuration#PROPERTY_AZURE_CLIENT_ID AZURE_CLIENT_ID}</li>
+ *     <li>{@link Configuration#PROPERTY_AZURE_CLIENT_CERTIFICATE_PATH AZURE_CLIENT_CERTIFICATE_PATH}</li>
+ *     <li>{@link Configuration#PROPERTY_AZURE_TENANT_ID AZURE_TENANT_ID}</li>
+ * </ul>
+ * or:
+ * <p>
+ * <ul>
+ *     <li>{@link Configuration#PROPERTY_AZURE_CLIENT_ID AZURE_CLIENT_ID}</li>
+ *     <li>{@link Configuration#PROPERTY_AZURE_USERNAME AZURE_USERNAME}</li>
+ *     <li>{@link Configuration#PROPERTY_AZURE_PASSWORD AZURE_PASSWORD}</li>
+ * </ul>
  */
 @Immutable
 public class EnvironmentCredential implements TokenCredential {
@@ -41,15 +55,22 @@ public class EnvironmentCredential implements TokenCredential {
 
     @Override
     public Mono<AccessToken> getToken(TokenRequestContext request) {
+        String clientId = configuration.get(Configuration.PROPERTY_AZURE_CLIENT_ID);
+        String tenantId = configuration.get(Configuration.PROPERTY_AZURE_TENANT_ID);
+        String clientSecret = configuration.get(Configuration.PROPERTY_AZURE_CLIENT_SECRET);
+        String certPath = configuration.get(Configuration.PROPERTY_AZURE_CLIENT_CERTIFICATE_PATH);
+        String username = configuration.get(Configuration.PROPERTY_AZURE_USERNAME);
+        String password = configuration.get(Configuration.PROPERTY_AZURE_PASSWORD);
         return Mono.fromSupplier(() -> {
-            if (configuration.contains(Configuration.PROPERTY_AZURE_CLIENT_ID)
-                && configuration.contains(Configuration.PROPERTY_AZURE_CLIENT_SECRET)
-                && configuration.contains(Configuration.PROPERTY_AZURE_TENANT_ID)) {
-                // TODO: support other clouds
-                return new ClientSecretCredential(configuration.get(Configuration.PROPERTY_AZURE_TENANT_ID),
-                    configuration.get(Configuration.PROPERTY_AZURE_CLIENT_ID),
-                    configuration.get(Configuration.PROPERTY_AZURE_CLIENT_SECRET),
-                    identityClientOptions);
+            if (verifyNotNull(clientId)) {
+                if (verifyNotNull(tenantId, clientSecret)) {
+                    // TODO: support other clouds
+                    return new ClientSecretCredential(tenantId, clientId, clientSecret, identityClientOptions);
+                } else if (verifyNotNull(tenantId, certPath)) {
+                    return new ClientCertificateCredential(tenantId, clientId, certPath, null, identityClientOptions);
+                } else if (verifyNotNull(username, password)) {
+                    return new UsernamePasswordCredential(clientId, tenantId, username, password, identityClientOptions);
+                }
             }
 
             // Other environment variables
@@ -58,4 +79,13 @@ public Mono<AccessToken> getToken(TokenRequestContext request) {
                 null));
         }).flatMap(cred -> cred.getToken(request));
     }
+
+    private boolean verifyNotNull(String... configs){
+        for(String config: configs){
+            if(config == null){
+                return false;
+            }
+        }
+        return true;
+    }
 }

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

@@ -17,11 +17,11 @@
 
 public class EnvironmentCredentialTests {
     @Test
-    public void testCreateEnvironmentCredential() {
-        Configuration configuration = Configuration.getGlobalConfiguration();
-        configuration.put(Configuration.PROPERTY_AZURE_CLIENT_ID, "foo");
-        configuration.put(Configuration.PROPERTY_AZURE_CLIENT_SECRET, "bar");
-        configuration.put(Configuration.PROPERTY_AZURE_TENANT_ID, "baz");
+    public void testCreateEnvironmentClientSecretCredential() {
+        Configuration.getGlobalConfiguration()
+            .put(Configuration.PROPERTY_AZURE_CLIENT_ID, "foo")
+            .put(Configuration.PROPERTY_AZURE_USERNAME, "bar")
+            .put(Configuration.PROPERTY_AZURE_PASSWORD, "baz");
 
         EnvironmentCredential credential = new EnvironmentCredentialBuilder().build();
 
@@ -36,4 +36,46 @@ public void testCreateEnvironmentCredential() {
             .expectNextMatches(token -> "token".equals(token.getToken()))
             .verifyComplete();
     }
+
+    @Test
+    public void testCreateEnvironmentClientCertificateCredential() {
+        Configuration.getGlobalConfiguration()
+            .put(Configuration.PROPERTY_AZURE_CLIENT_ID, "foo")
+            .put(Configuration.PROPERTY_AZURE_USERNAME, "bar")
+            .put(Configuration.PROPERTY_AZURE_PASSWORD, "baz");
+
+        EnvironmentCredential credential = new EnvironmentCredentialBuilder().build();
+
+        // authentication will fail client-id=foo, but should be able to create ClientCertificateCredential
+        StepVerifier.create(credential.getToken(new TokenRequestContext().addScopes("qux/.default"))
+            .doOnSuccess(s -> fail())
+            .onErrorResume(t -> {
+                String message = t.getMessage();
+                Assert.assertFalse(message != null && message.contains("Cannot create any credentials with the current environment variables"));
+                return Mono.just(new AccessToken("token", OffsetDateTime.MAX));
+            }))
+            .expectNextMatches(token -> "token".equals(token.getToken()))
+            .verifyComplete();
+    }
+
+    @Test
+    public void testCreateEnvironmentUserPasswordCredential() {
+        Configuration.getGlobalConfiguration()
+            .put(Configuration.PROPERTY_AZURE_CLIENT_ID, "foo")
+            .put(Configuration.PROPERTY_AZURE_USERNAME, "bar")
+            .put(Configuration.PROPERTY_AZURE_PASSWORD, "baz");
+
+        EnvironmentCredential credential = new EnvironmentCredentialBuilder().build();
+
+        // authentication will fail client-id=foo, but should be able to create UsernamePasswordCredential
+        StepVerifier.create(credential.getToken(new TokenRequestContext().addScopes("qux/.default"))
+            .doOnSuccess(s -> fail())
+            .onErrorResume(t -> {
+                String message = t.getMessage();
+                Assert.assertFalse(message != null && message.contains("Cannot create any credentials with the current environment variables"));
+                return Mono.just(new AccessToken("token", OffsetDateTime.MAX));
+            }))
+            .expectNextMatches(token -> "token".equals(token.getToken()))
+            .verifyComplete();
+    }
 }