Add relative path loading for certificates.

Author: brendanburns

util/src/main/java/io/kubernetes/client/util/ClientBuilder.java

@@ -265,7 +265,7 @@ public static ClientBuilder kubeconfig(KubeConfig config) throws IOException {
     }
 
     final byte[] caBytes =
-        KubeConfig.getDataOrFile(
+        config.getDataOrFileRelative(
             config.getCertificateAuthorityData(), config.getCertificateAuthorityFile());
     if (caBytes != null) {
       builder.setCertificateAuthority(caBytes);

util/src/main/java/io/kubernetes/client/util/KubeConfig.java

@@ -395,7 +395,15 @@ private static Map<String, Object> findObject(ArrayList<Object> list, String nam
     return null;
   }
 
-  public static byte[] getDataOrFile(final String data, final String file) throws IOException {
+  public byte[] getDataOrFileRelative(final String data, final String path) throws IOException {
+    String resolvedPath = path;
+    if (resolvedPath != null && this.file != null) {
+      resolvedPath = this.file.toPath().getParent().resolve(path).normalize().toString();
+    }
+    return getDataOrFile(data, resolvedPath);
+  }
+
+  private static byte[] getDataOrFile(final String data, final String file) throws IOException {
     if (data != null) {
       return Base64.decodeBase64(data);
     }

util/src/main/java/io/kubernetes/client/util/credentials/KubeconfigAuthentication.java

@@ -25,9 +25,10 @@ public class KubeconfigAuthentication implements Authentication {
 
   public KubeconfigAuthentication(final KubeConfig config) throws IOException {
     this.clientCert =
-        KubeConfig.getDataOrFile(
+        config.getDataOrFileRelative(
             config.getClientCertificateData(), config.getClientCertificateFile());
-    this.clientKey = KubeConfig.getDataOrFile(config.getClientKeyData(), config.getClientKeyFile());
+    this.clientKey =
+        config.getDataOrFileRelative(config.getClientKeyData(), config.getClientKeyFile());
     this.username = config.getUsername();
     this.password = config.getPassword();
     this.token = config.getAccessToken();