Support for auth within Kubernetes and generic JWT

src/main/java/com/bettercloud/vault/api/Auth.java

@@ -879,31 +879,32 @@ public AuthResponse loginByGithub(final String githubToken, final String githubA
     }
 
     /**
-     * <p>Basic login operation to authenticate to an GCP backend.  Example usage:</p>
+     * <p>Basic login operation to authenticate to an JWT backend.  Example usage:</p>
      *
      * <blockquote>
      * <pre>{@code
-     * final AuthResponse response = vault.auth().loginByGCP("dev", "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...");
+     * final AuthResponse response = vault.auth().loginByJwt("kubernetes", "dev", "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...");
      *
      * final String token = response.getAuthClientToken();
      * }</pre>
      * </blockquote>
      *
+     * @param provider Provider of JWT token.
      * @param role The gcp role used for authentication
      * @param jwt  The JWT token for the role
      * @return The auth token, with additional response metadata
      * @throws VaultException If any error occurs, or unexpected response received from Vault
      */
     // TODO: Needs integration test coverage if possible
-    public AuthResponse loginByGCP(final String role, final String jwt) throws VaultException {
+    public AuthResponse loginByJwt(final String provider, final String role, final String jwt) throws VaultException {
         int retryCount = 0;
 
         while (true) {
             try {
                 // HTTP request to Vault
                 final String requestJson = Json.object().add("role", role).add("jwt", jwt).toString();
                 final RestResponse restResponse = new Rest()
-                        .url(config.getAddress() + "/v1/auth/gcp/login")
+                        .url(config.getAddress() + "/v1/auth/" + provider + "/login")
                         .optionalHeader("X-Vault-Namespace", this.nameSpace)
                         .body(requestJson.getBytes(StandardCharsets.UTF_8))
                         .connectTimeoutSeconds(config.getOpenTimeout())
@@ -941,6 +942,50 @@ public AuthResponse loginByGCP(final String role, final String jwt) throws Vault
         }
     }
 
+
+    /**
+     * <p>Basic login operation to authenticate to an GCP backend.  Example usage:</p>
+     *
+     * <blockquote>
+     * <pre>{@code
+     * final AuthResponse response = vault.auth().loginByGCP("dev", "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...");
+     *
+     * final String token = response.getAuthClientToken();
+     * }</pre>
+     * </blockquote>
+     *
+     * @param role The gcp role used for authentication
+     * @param jwt  The JWT token for the role
+     * @return The auth token, with additional response metadata
+     * @throws VaultException If any error occurs, or unexpected response received from Vault
+     */
+    public AuthResponse loginByGCP(final String role, final String jwt) throws VaultException {
+        return loginByJwt("gcp", role, jwt);
+    }
+
+
+    /**
+     * Basic login operation to authenticate to an kubernetes backend. Example usage:
+     *
+     * <blockquote>
+     *
+     * <pre>{@code
+     * final AuthResponse response =
+     *     vault.auth().loginByKubernetes("dev", "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...");
+     *
+     * final String token = response.getAuthClientToken();
+     * }</pre>
+     * </blockquote>
+     *
+     * @param role The kubernetes role used for authentication
+     * @param jwt The JWT token for the role, typically read from /var/run/secrets/kubernetes.io/serviceaccount/token
+     * @return The auth token, with additional response metadata
+     * @throws VaultException If any error occurs, or unexpected response received from Vault
+     */
+    private AuthResponse loginByKubernetes(final String role, final String jwt) throws VaultException {
+        return loginByJwt("kubernetes", role, jwt);
+    }
+
     /**
      * <p>Basic login operation to authenticate using Vault's TLS Certificate auth backend.  Example usage:</p>
      *