Library to connect to a pg-backup-api server.

Module to provide communication with a server in order to send new
tasks and query them.

pg-backup-api is a REST api that at the moment, is integrated with
barman only, and can provide a communication interface in order to
perform remote recoveries through background tasks. There are cases
where instead of writing a new repmgr module of some feature that
exists in backup tools already, like barman, pg-backup-api can
provide that integration.

pgbackupapi.c

@@ -0,0 +1,147 @@
+/*
+ * pgbackupapi.c
+ * Copyright (c) EnterpriseDB Corporation, 2010-2021
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+
+#include <curl/curl.h>
+#include <json-c/json.h>
+
+#include "repmgr.h"
+#include "pgbackupapi.h"
+
+
+size_t receive_operations_cb(void *content, size_t size, size_t nmemb, char *buffer) {
+	short int max_chars_to_copy = MAX_BUFFER_LENGTH -2;
+	short int i = 0;
+	int operation_length = 0;
+	json_object *value;
+
+	json_object *root = json_tokener_parse(content);
+	json_object *operations = json_object_object_get(root, "operations");
+
+	operation_length = strlen(json_object_get_string(operations));
+	if (operation_length < max_chars_to_copy) {
+		max_chars_to_copy = operation_length;
+	}
+
+	strncpy(buffer, json_object_get_string(operations), max_chars_to_copy);
+
+	fprintf(stdout, "Success! The following operations were found\n");
+	for (i=0; i<json_object_array_length(operations); i++) {
+		value = json_object_array_get_idx(operations, i);
+		printf("%s\n", json_object_get_string(value));
+	}
+	return size * nmemb;
+}
+
+char * define_base_url(operation_task *task) {
+	char *format = "http://%s:80/servers/%s/operations";
+	char *url = malloc(MAX_BUFFER_LENGTH);
+
+	snprintf(url, MAX_BUFFER_LENGTH-1, format, task->host, task->node_name);
+
+	//`url` is freed on the function that called this
+	return url;
+}
+
+CURLcode get_operations_on_server(CURL *curl, operation_task *task) {
+	char buffer[MAX_BUFFER_LENGTH];
+	char *url = define_base_url(task);
+	CURLcode ret;
+
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, receive_operations_cb);
+	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer);
+	curl_easy_setopt(curl, CURLOPT_URL, url);
+
+	ret = curl_easy_perform(curl);
+	free(url);
+
+	return ret;
+}
+
+size_t receive_operation_id(void *content, size_t size, size_t nmemb, char *buffer) {
+	json_object *root = json_tokener_parse(content);
+	json_object *operation = json_object_object_get(root, "operation_id");
+
+	if (operation != NULL) {
+		strncpy(buffer, json_object_get_string(operation), MAX_BUFFER_LENGTH-2);
+	}
+
+	return size * nmemb;
+}
+
+
+CURLcode create_new_task(CURL *curl, operation_task *task) {
+	PQExpBufferData payload;
+	char *url = define_base_url(task);
+	CURLcode ret;
+	json_object *root = json_object_new_object();
+	struct curl_slist *chunk = NULL;
+
+	json_object_object_add(root, "operation_type", json_object_new_string(task->operation_type));
+	json_object_object_add(root, "backup_id", json_object_new_string(task->backup_id));
+	json_object_object_add(root, "remote_ssh_command", json_object_new_string(task->remote_ssh_command));
+	json_object_object_add(root, "destination_directory", json_object_new_string(task->destination_directory));
+
+	initPQExpBuffer(&payload);
+	appendPQExpBufferStr(&payload, json_object_to_json_string(root));
+
+	chunk = curl_slist_append(chunk, "Content-type: application/json");
+	curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk);
+	curl_easy_setopt(curl, CURLOPT_URL, url);
+	curl_easy_setopt(curl, CURLOPT_POSTFIELDS, payload.data);
+	curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1L);
+	//curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, receive_operation_id);
+	curl_easy_setopt(curl, CURLOPT_WRITEDATA, task->operation_id);
+	ret = curl_easy_perform(curl);
+	free(url);
+	termPQExpBuffer(&payload);
+
+	return ret;
+}
+
+
+size_t receive_operation_status(void *content, size_t size, size_t nmemb, char *buffer) {
+	json_object *root = json_tokener_parse(content);
+	json_object *status = json_object_object_get(root, "status");
+	if (status != NULL) {
+		strncpy(buffer, json_object_get_string(status), MAX_BUFFER_LENGTH-2);
+	}
+	else {
+		fprintf(stderr, "Incorrect reply received for that operation ID.\n");
+		strcpy(buffer, "\0");
+	}
+	return size * nmemb;
+}
+
+CURLcode get_status_of_operation(CURL *curl, operation_task *task) {
+	CURLcode ret;
+	char *url = define_base_url(task);
+
+	strcat(url, "/");
+	strcat(url, task->operation_id);
+	curl_easy_setopt(curl, CURLOPT_URL, url);
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, receive_operation_status);
+	curl_easy_setopt(curl, CURLOPT_WRITEDATA, task->operation_status);
+
+	ret = curl_easy_perform(curl);
+	free(url);
+
+	return ret;
+}

pgbackupapi.h

@@ -0,0 +1,46 @@
+/*
+ * pgbackupapi.h
+ * Copyright (c) EnterpriseDB Corporation, 2010-2021
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <curl/curl.h>
+#include <json-c/json.h>
+
+typedef struct operation_task {
+        char *backup_id;
+        char *destination_directory;
+        char *operation_type;
+	char *operation_id;
+	char *operation_status;
+        char *remote_ssh_command;
+	char *host;
+	char *node_name;
+} operation_task;
+
+//Default simplebuffer size in most of operations
+#define MAX_BUFFER_LENGTH 72
+
+//Callbacks to send/receive data from pg-backup-api endpoints
+size_t receive_operations_cb(void *content, size_t size, size_t nmemb, char *buffer);
+size_t receive_operation_id(void *content, size_t size, size_t nmemb, char *buffer);
+size_t receive_operation_status(void *content, size_t size, size_t nmemb, char *buffer);
+
+//Functions that implement the logic and know what to do and how to comunnicate wuth the API
+CURLcode get_operations_on_server(CURL *curl, operation_task *task);
+CURLcode create_new_task(CURL *curl, operation_task *task);
+CURLcode get_status_of_operation(CURL *curl, operation_task *task);
+
+//Helper to make simpler to read the handler where we set the URL
+char * define_base_url(operation_task *task);

repmgr.h

@@ -116,6 +116,7 @@
 #define DEFAULT_STANDBY_FOLLOW_TIMEOUT       30  /* seconds */
 #define DEFAULT_STANDBY_FOLLOW_RESTART       false
 #define DEFAULT_SHUTDOWN_CHECK_TIMEOUT       60  /* seconds */
+#define DEFAULT_STANDBY_PG_BACKUPAPI_OP_TYPE "recovery"
 #define DEFAULT_STANDBY_RECONNECT_TIMEOUT    60  /* seconds */
 #define DEFAULT_NODE_REJOIN_TIMEOUT          60  /* seconds */
 #define DEFAULT_ARCHIVE_READY_WARNING        16  /* WAL files */