add more useful error messages for OpenShift

CHANGELOG.md

@@ -9,6 +9,7 @@ Master (unreleased)
 * \[test\] Run tests against Java 11 [#30](https://github.com/jenkinsci/kubernetes-credentials-plugin/pull/30)
 * use Secret instead of String for sensitive data [#31](https://github.com/jenkinsci/kubernetes-credentials-plugin/pull/31)
 * change minimal Jenkins version for 2.222.1 LTS [42edb2ef](https://github.com/jenkinsci/kubernetes-credentials-plugin/commit/42edb2efffb1415f055975667f351f13ed8f4642)
+* make OpenshiftBearerToken errors more helpful [#32](https://github.com/jenkinsci/kubernetes-credentials-plugin/pull/32)
 
 0.8.0
 -----

src/main/java/org/jenkinsci/plugins/kubernetes/credentials/OpenShiftBearerTokenCredentialImpl.java

@@ -8,16 +8,19 @@
 import org.apache.commons.codec.binary.Base64;
 import org.apache.http.Header;
 import org.apache.http.NameValuePair;
+import org.apache.http.client.ClientProtocolException;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.utils.URLEncodedUtils;
+import org.apache.http.conn.HttpHostConnectException;
 import org.apache.http.impl.client.HttpClientBuilder;
 import org.apache.http.util.EntityUtils;
 import org.kohsuke.stapler.DataBoundConstructor;
 
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.net.UnknownHostException;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;
@@ -103,12 +106,18 @@ public String getToken(String apiServerURL, String caCertData, boolean skipTlsVe
         if (token == null || System.currentTimeMillis() > token.expire) {
             try {
                 token = refreshToken(apiServerURL, caCertData, skipTlsVerify);
+            } catch (ClientProtocolException e) {
+                throw new IOException("Can't parse protocol in the OAuth server URL ('" + apiServerURL + "')", e);
             } catch (HttpClientWithTLSOptionsFactory.TLSConfigurationError e) {
                 throw new IOException("Could not configure SSL Factory in HttpClientWithTLSOptionsFactory: " + e.getMessage(), e);
-            } catch (URISyntaxException e) {
-                throw new IOException("The OAuth server URL was invalid ('" + apiServerURL + "'): " + e.getMessage(), e);
+            } catch (HttpHostConnectException e) {
+                throw new IOException("Can't connect to the OAuth server ('" + apiServerURL + "'): " + e.getMessage(), e);
             } catch (TokenResponseError e) {
                 throw new IOException("The response from the OAuth server was invalid: " + e.getMessage(), e);
+            } catch (UnknownHostException e) {
+                throw new IOException("Can't resolve OAuth server hostname ('" + apiServerURL + "'): " + e.getMessage(), e);
+            } catch (URISyntaxException e) {
+                throw new IOException("The OAuth server URL was invalid ('" + apiServerURL + "'): " + e.getMessage(), e);
             }
 
             this.tokenCache.put(apiServerURL, token);