add support to load kubernetes configuration for memory buffer

- existing api is not changed
   - load_kube_config works as before
- extend kubeconfig_t to hold in memory buffer
- make a common flow for file/buffer code
- set fileName/buffer members accordingly
- provide new api: load_kube_config_buffer

kubernetes/config/kube_config.c

@@ -304,21 +304,14 @@ static int kuberconfig_auth_provider(kubeconfig_property_t * current_user, kubec
     return rc;
 }
 
-int load_kube_config(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, const char *configFileName)
+int load_kube_config_common(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, kubeconfig_t *kubeconfig)
 {
-    static char fname[] = "load_kube_config()";
+    static char fname[] = "load_kube_config_common()";
     int rc = 0;
     const kubeconfig_property_t *current_context = NULL;
     const kubeconfig_property_t *current_cluster = NULL;
     kubeconfig_property_t *current_user = NULL;
 
-    kubeconfig_t *kubeconfig = kubeconfig_create();
-    if (!kubeconfig) {
-        fprintf(stderr, "%s: Cannot create kubeconfig.[%s]\n", fname, strerror(errno));
-        return -1;
-    }
-
-    kubeconfig->fileName = getWorkingConfigFile(configFileName);
     rc = kubeyaml_load_kubeconfig(kubeconfig);
     if (0 != rc) {
         fprintf(stderr, "%s: Cannot load the kubeconfig %s\n", fname, kubeconfig->fileName);
@@ -393,8 +386,48 @@ int load_kube_config(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApi
     }
 
   end:
+    return rc;
+}
+
+int load_kube_config(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, const char *configFileName)
+{
+    static char fname[] = "load_kube_config()";
+    int rc = 0;
+
+    kubeconfig_t *kubeconfig = kubeconfig_create();
+    if (!kubeconfig) {
+        fprintf(stderr, "%s: Cannot create kubeconfig.[%s]\n", fname, strerror(errno));
+        return -1;
+    }
+
+    kubeconfig->fileName = getWorkingConfigFile(configFileName);
+
+    rc = load_kube_config_common(pBasePath, pSslConfig, pApiKeys, kubeconfig);
+
+    kubeconfig_free(kubeconfig);
+    kubeconfig = NULL;
+
+    return rc;
+}
+
+int load_kube_config_buffer(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, const char *buffer)
+{
+    static char fname[] = "load_kube_config_buffer()";
+    int rc = 0;
+
+    kubeconfig_t *kubeconfig = kubeconfig_create();
+    if (!kubeconfig) {
+        fprintf(stderr, "%s: Cannot create kubeconfig.[%s]\n", fname, strerror(errno));
+        return -1;
+    }
+
+    kubeconfig->buffer = strdup(buffer);
+
+    rc = load_kube_config_common(pBasePath, pSslConfig, pApiKeys, kubeconfig);
+
     kubeconfig_free(kubeconfig);
     kubeconfig = NULL;
+
     return rc;
 }
 

kubernetes/config/kube_config.h

@@ -46,6 +46,44 @@ extern "C" {
 
     int load_kube_config(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, const char *configFileName);
 
+/*
+ * load_kube_config_buffer
+ *
+ *
+ * Description:
+ *
+ *
+ * Load kubernetes cluster configuration from specfied buffer
+ *
+ *
+ * Return:
+ *
+ *   0     Success
+ *  -1     Failed
+ *
+ *
+ * Parameter:
+ *
+ *
+ * IN:
+
+ * buffer : kubernetes cluster configuration data
+ *
+ *
+ * OUT:
+ *
+ * pBasePath: The pointer to API server address
+ * pSslConfig: The pointer to SSL configuration for client
+ * pApiKeys: The pointer to API tokens for client
+ *
+ * The memory will be allocated inside this function. User 
+ * should call free_client_config to free the memory after 
+ * these parameters are not used.
+ *
+ */
+
+    int load_kube_config_buffer(char **pBasePath, sslConfig_t ** pSslConfig, list_t ** pApiKeys, const char *buffer);
+
 /*
  * free_client_config
  *

kubernetes/config/kube_config_model.c

@@ -224,6 +224,10 @@ void kubeconfig_free(kubeconfig_t * kubeconfig)
         free(kubeconfig->fileName);
         kubeconfig->fileName = NULL;
     }
+    if (kubeconfig->buffer) {
+        free(kubeconfig->buffer);
+        kubeconfig->buffer = NULL;
+    }
     if (kubeconfig->apiVersion) {
         free(kubeconfig->apiVersion);
         kubeconfig->apiVersion = NULL;

kubernetes/config/kube_config_model.h

@@ -88,6 +88,7 @@ extern "C" {
 
     typedef struct kubeconfig_t {
         char *fileName;
+        char *buffer;
         char *apiVersion;
         char *preferences;
         char *kind;

kubernetes/config/kube_config_yaml.c

@@ -430,25 +430,33 @@ int kubeyaml_load_kubeconfig(kubeconfig_t * kubeconfig)
 {
     static char fname[] = "kubeyaml_load_kubeconfig()";
 
-    /* Set a file input. */
+    /* Set a file input or use the provided buffer. */
     FILE *input = NULL;
     if (kubeconfig->fileName) {
         input = fopen(kubeconfig->fileName, "rb");
         if (!input) {
             fprintf(stderr, "%s: Cannot open the file %s.[%s]\n", fname, kubeconfig->fileName, strerror(errno));
             return -1;
         }
+    else if (kubeconfig->buffer) {
+        // Nothing to do here for now.
+    }
     } else {
         fprintf(stderr, "%s: The kubeconf file name needs be set by kubeconfig->fileName .\n", fname);
         return -1;
     }
 
+    /* Create the Parser object. */
     yaml_parser_t parser;
     yaml_document_t document;
 
-    /* Create the Parser object. */
     yaml_parser_initialize(&parser);
-    yaml_parser_set_input_file(&parser, input);
+    if (input) {
+        yaml_parser_set_input_file(&parser, input);
+    }
+    else {
+        yaml_parser_set_input_string(&parser, (const unsigned char*)kubeconfig->buffer, strlen(kubeconfig->buffer));
+    }
 
     int done = 0;
     while (!done) {

kubernetes/config/kube_config_yaml.h

@@ -24,13 +24,15 @@ extern "C" {
  *
  * IN:
  * kubeconfig->fileName: kubernetes cluster configuration file name
- *
+ * kubeconfig->buffer: kubernetes cluster configuration data; this is considered only if kubeconfig->fileName is set to NULL
+ * 
  * OUT:
  * kubeconfig: kubernetes cluster configuration
  *
  */
     int kubeyaml_load_kubeconfig(kubeconfig_t * kubeconfig);
 
+
 /*
  * kubeyaml_parse_exec_crendential
  *