SERVER-43744 Add logFormat configure option (logv2 only)

Author: henrikedin

src/mongo/db/initialize_server_global_state.cpp

@@ -355,6 +355,9 @@ MONGO_INITIALIZER_GENERAL(ServerLogRedirection,
     logger::globalLogDomain()->attachAppender(
         std::make_unique<RamLogAppender>(RamLog::get("global")));
 
+    if (serverGlobalParams.logV2)
+        lv2Manager.setOutputFormat(serverGlobalParams.logFormat);
+
     return Status::OK();
 }
 

src/mongo/db/server_options.h

@@ -30,6 +30,7 @@
 #pragma once
 
 #include "mongo/db/jsobj.h"
+#include "mongo/logv2/log_format.h"
 #include "mongo/platform/atomic_word.h"
 #include "mongo/platform/process_id.h"
 #include "mongo/stdx/variant.h"
@@ -96,7 +97,8 @@ struct ServerGlobalParams {
     std::string pidFile;           // Path to pid file, or empty if none.
     std::string timeZoneInfoPath;  // Path to time zone info directory, or empty if none.
 
-    std::string logpath;            // Path to log file, if logging to a file; otherwise, empty.
+    std::string logpath;  // Path to log file, if logging to a file; otherwise, empty.
+    logv2::LogFormat logFormat = logv2::LogFormat::kDefault;  // Log format to output to
     bool logAppend = false;         // True if logging to a file in append mode.
     bool logRenameOnRotate = true;  // True if logging should rename log files on rotate
     bool logWithSyslog = false;     // True if logging to syslog; must not be set if logpath is set.

src/mongo/db/server_options_base.idl

@@ -132,7 +132,11 @@ configs:
         arg_vartype: String
         condition:
             preprocessor: '!defined(_WIN32)'
-
+    'systemLog.logFormat':
+        description: 'Set the log output format (default|text|json)'
+        short_name: logFormat
+        arg_vartype: String
+        default: "default"
     'systemLog.logAppend':
         description: 'Append to logpath instead of over-writing'
         short_name: logappend

src/mongo/db/server_options_helpers.cpp

@@ -378,6 +378,24 @@ Status storeBaseOptions(const moe::Environment& params) {
     }
 #endif  // _WIN32
 
+    if (params.count("systemLog.logFormat")) {
+        std::string formatStr = params["systemLog.logFormat"].as<string>();
+        if (!serverGlobalParams.logV2 && formatStr != "default")
+            return Status(ErrorCodes::BadValue,
+                          "Can only use systemLog.logFormat if logv2 is enabled.");
+        if (formatStr == "default") {
+            serverGlobalParams.logFormat = logv2::LogFormat::kDefault;
+        } else if (formatStr == "text") {
+            serverGlobalParams.logFormat = logv2::LogFormat::kText;
+        } else if (formatStr == "json") {
+            serverGlobalParams.logFormat = logv2::LogFormat::kJson;
+        } else {
+            return Status(ErrorCodes::BadValue,
+                          "Unsupported value for logFormat: " + formatStr +
+                              ". Valid values are: default, text or json");
+        }
+    }
+
     if (params.count("systemLog.logAppend") && params["systemLog.logAppend"].as<bool>() == true) {
         serverGlobalParams.logAppend = true;
     }

src/mongo/logv2/log_format.h

@@ -0,0 +1,36 @@
+/**
+ *    Copyright (C) 2019-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    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
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+namespace mongo {
+namespace logv2 {
+enum class LogFormat { kDefault, kText, kJson };
+}  // namespace logv2
+}  // namespace mongo

src/mongo/logv2/log_manager.cpp

@@ -145,6 +145,19 @@ struct LogManager::Impl {
         _rotatableFileBackend->set_formatter(TextFormatter());
     }
 
+    template <class Formatter>
+    void setFormatterToAllBackends() {
+        _consoleBackend->set_formatter(Formatter());
+        _globalLogCacheBackend->set_formatter(Formatter());
+        _startupWarningsBackend->set_formatter(Formatter());
+        if (_rotatableFileBackend)
+            _rotatableFileBackend->set_formatter(Formatter());
+#ifndef _WIN32
+        if (_syslogBackend)
+            _syslogBackend->set_formatter(Formatter());
+#endif
+    }
+
     LogDomain _globalDomain{std::make_unique<LogDomainGlobal>()};
     // I think that, technically, these are logging front ends
     // and that they get to hold or wrap a backend
@@ -155,6 +168,7 @@ struct LogManager::Impl {
 #endif
     boost::shared_ptr<RamLogBackend> _globalLogCacheBackend;
     boost::shared_ptr<RamLogBackend> _startupWarningsBackend;
+    LogFormat _format{LogFormat::kDefault};
     bool _defaultBackendsAttached{false};
 };
 
@@ -182,6 +196,24 @@ LogDomain& LogManager::getGlobalDomain() {
     return _impl->_globalDomain;
 }
 
+void LogManager::setOutputFormat(LogFormat format) {
+    if (_impl->_format != format) {
+        switch (format) {
+            case LogFormat::kText:
+                _impl->setFormatterToAllBackends<TextFormatter>();
+                break;
+
+            case LogFormat::kJson:
+                _impl->setFormatterToAllBackends<JsonFormatter>();
+                break;
+
+            default:
+                break;
+        };
+        _impl->_format = format;
+    }
+}
+
 void LogManager::detachDefaultBackends() {
     invariant(isDefaultBackendsAttached());
 

src/mongo/logv2/log_manager.h

@@ -29,6 +29,8 @@
 
 #pragma once
 
+#include "mongo/logv2/log_format.h"
+
 #include <memory>
 #include <string>
 
@@ -58,6 +60,8 @@ class LogManager {
      */
     LogDomain& getGlobalDomain();
 
+    void setOutputFormat(LogFormat format);
+
     /**
      * Detaches the default log backends
      *