Honor Discovery URL for flows other than M2M + fallback for discovery URL

databricks-sdk-java/src/main/java/com/databricks/sdk/core/DatabricksConfig.java

@@ -13,8 +13,11 @@
 import java.lang.reflect.Field;
 import java.util.*;
 import org.apache.http.HttpMessage;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class DatabricksConfig {
+  private static final Logger LOG = LoggerFactory.getLogger(DatabricksConfig.class);
   private CredentialsProvider credentialsProvider = new DefaultCredentialsProvider();
 
   @ConfigAttribute(env = "DATABRICKS_HOST")
@@ -545,7 +548,19 @@ public OpenIDConnectEndpoints getOidcEndpoints() throws IOException {
     if (discoveryUrl == null) {
       return fetchDefaultOidcEndpoints();
     }
-    return fetchOidcEndpointsFromDiscovery();
+    try {
+      OpenIDConnectEndpoints oidcEndpoints = fetchOidcEndpointsFromDiscovery();
+      if (oidcEndpoints != null) {
+        return oidcEndpoints;
+      }
+    } catch (Exception e) {
+      LOG.warn(
+          "Failed to fetch OIDC Endpoints using discovery URL: {}. Error: {}. \nDefaulting to fetch OIDC using default endpoint.",
+          discoveryUrl,
+          e.getMessage(),
+          e);
+    }
+    return fetchDefaultOidcEndpoints();
   }
 
   private OpenIDConnectEndpoints fetchOidcEndpointsFromDiscovery() {
@@ -632,6 +647,7 @@ public DatabricksEnvironment getDatabricksEnvironment() {
   }
 
   private DatabricksConfig clone(Set<String> fieldsToSkip) {
+    fieldsToSkip.add("LOG");
     DatabricksConfig newConfig = new DatabricksConfig();
     for (Field f : DatabricksConfig.class.getDeclaredFields()) {
       if (fieldsToSkip.contains(f.getName())) {

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/OAuthClient.java

@@ -31,6 +31,7 @@ public class OAuthClient {
   public static class Builder {
     private String host;
     private String clientId;
+    private String discoveryUrl;
     private String redirectUrl;
     private List<String> scopes;
     private String clientSecret;
@@ -53,6 +54,11 @@ public Builder withClientId(String clientId) {
       return this;
     }
 
+    public Builder withDiscoveryUrl(String discoveryUrl) {
+      this.discoveryUrl = discoveryUrl;
+      return this;
+    }
+
     public Builder withClientSecret(String clientSecret) {
       this.clientSecret = clientSecret;
       return this;
@@ -91,6 +97,7 @@ public OAuthClient(DatabricksConfig config) throws IOException {
             .withHttpClient(config.getHttpClient())
             .withClientId(config.getClientId())
             .withClientSecret(config.getClientSecret())
+            .withDiscoveryUrl(config.getDiscoveryUrl())
             .withHost(config.getHost())
             .withRedirectUrl(
                 config.getOAuthRedirectUrl() != null
@@ -106,7 +113,8 @@ private OAuthClient(Builder b) throws IOException {
     this.host = b.host;
     this.hc = b.hc;
 
-    DatabricksConfig config = new DatabricksConfig().setHost(b.host).resolve();
+    DatabricksConfig config =
+        new DatabricksConfig().setHost(b.host).setDiscoveryUrl(b.discoveryUrl).resolve();
     OpenIDConnectEndpoints oidc = config.getOidcEndpoints();
     if (oidc == null) {
       throw new DatabricksException(b.host + " does not support OAuth");

databricks-sdk-java/src/test/java/com/databricks/sdk/core/DatabricksConfigTest.java

@@ -159,6 +159,35 @@ public void testDiscoveryEndpoint() throws IOException {
     }
   }
 
+  @Test
+  public void testDiscoveryEndpointFetchThrowsError() throws IOException {
+    String discoveryUrlSuffix = "/test.discovery.url";
+    String OIDCResponse =
+        "{\n"
+            + "  \"authorization_endpoint\": \"https://test.auth.endpoint/oidc/v1/authorize\",\n"
+            + "  \"token_endpoint\": \"https://test.auth.endpoint/oidc/v1/token\"\n"
+            + "}";
+
+    try (FixtureServer server =
+        new FixtureServer()
+            .with("GET", discoveryUrlSuffix, "", 400)
+            .with("GET", "/oidc/.well-known/oauth-authorization-server", OIDCResponse, 200)) {
+
+      String discoveryUrl = server.getUrl() + discoveryUrlSuffix;
+
+      OpenIDConnectEndpoints oidcEndpoints =
+          new DatabricksConfig()
+              .setHost(server.getUrl())
+              .setDiscoveryUrl(discoveryUrl)
+              .setHttpClient(new CommonsHttpClient.Builder().withTimeoutSeconds(30).build())
+              .getOidcEndpoints();
+
+      assertEquals(
+          oidcEndpoints.getAuthorizationEndpoint(), "https://test.auth.endpoint/oidc/v1/authorize");
+      assertEquals(oidcEndpoints.getTokenEndpoint(), "https://test.auth.endpoint/oidc/v1/token");
+    }
+  }
+
   @Test
   public void testNewWithWorkspaceHost() {
     DatabricksConfig config =