feat: Optional log rotation (#3016)

This PR adds an option to disable log rotation.

src/util/config/ConfigDefinition.cpp

@@ -422,6 +422,8 @@ getClioConfig()
          {"log.directory_max_files",
           ConfigValue{ConfigType::Integer}.defaultValue(25).withConstraint(gValidateUint32)},
 
+         {"log.rotate", ConfigValue{ConfigType::Boolean}.defaultValue(true)},
+
          {"log.tag_style",
           ConfigValue{ConfigType::String}.defaultValue("none").withConstraint(gValidateLogTag)},
 

src/util/config/ConfigDescription.hpp

@@ -357,6 +357,10 @@ Documentation can be found at: <https://github.com/gabime/spdlog/wiki/Custom-for
                     "file starts."},
         KV{.key = "log.directory_max_files",
            .value = "The maximum number of log files in the directory."},
+        KV{.key = "log.rotate",
+           .value = "Enables or disables log file rotation. When disabled, a single log file is "
+                    "used without size-based rotation. Useful when rotation is managed externally "
+                    "(e.g., via logrotate)."},
         KV{.key = "log.tag_style",
            .value = "Log tags are unique identifiers for log messages. `uint`/`int` starts logging "
                     "from 0 and increments, "

src/util/log/Logger.cpp

@@ -17,6 +17,7 @@
 #include <spdlog/formatter.h>
 #include <spdlog/logger.h>
 #include <spdlog/pattern_formatter.h>
+#include <spdlog/sinks/basic_file_sink.h>
 #include <spdlog/sinks/rotating_file_sink.h>
 #include <spdlog/sinks/stdout_color_sinks.h>
 #include <spdlog/spdlog.h>
@@ -184,12 +185,18 @@ spdlog::sink_ptr
 LogService::createFileSink(FileLoggingParams const& params, std::string const& format)
 {
     std::filesystem::path const dirPath(params.logDir);
-    // the below are taken from user in MB, but spdlog needs it to be in bytes
-    auto const rotationSize = mbToBytes(params.rotationSizeMB);
+    auto fileSink = [&]() -> std::shared_ptr<spdlog::sinks::sink> {
+        auto const logPath = (dirPath / "clio.log").string();
+        if (params.rotation.has_value()) {
+            // rotation sizes are taken from user in MB, but spdlog needs bytes
+            auto const rotationSize = mbToBytes(params.rotation->sizeMB);
+            return std::make_shared<spdlog::sinks::rotating_file_sink_mt>(
+                logPath, rotationSize, params.rotation->maxFiles
+            );
+        }
+        return std::make_shared<spdlog::sinks::basic_file_sink_mt>(logPath, /*truncate=*/false);
+    }();
 
-    auto fileSink = std::make_shared<spdlog::sinks::rotating_file_sink_mt>(
-        (dirPath / "clio.log").string(), rotationSize, params.dirMaxFiles
-    );
     fileSink->set_level(spdlog::level::trace);
     fileSink->set_formatter(std::make_unique<spdlog::pattern_formatter>(format));
 
@@ -336,10 +343,17 @@ LogService::getSinks(config::ClioConfigDefinition const& config)
             }
         }
 
+        std::optional<RotationParams> rotation = std::nullopt;
+        if (config.get<bool>("log.rotate")) {
+            rotation = RotationParams{
+                .sizeMB = config.get<uint32_t>("log.rotation_size"),
+                .maxFiles = config.get<uint32_t>("log.directory_max_files"),
+            };
+        }
+
         FileLoggingParams const params{
             .logDir = logDir.value(),
-            .rotationSizeMB = config.get<uint32_t>("log.rotation_size"),
-            .dirMaxFiles = config.get<uint32_t>("log.directory_max_files"),
+            .rotation = rotation,
         };
         allSinks.push_back(createFileSink(params, format));
     }

src/util/log/Logger.hpp

@@ -28,6 +28,7 @@ class sink;  // NOLINT(readability-identifier-naming)
 struct BenchmarkLoggingInitializer;
 class LoggerFixture;
 struct LogServiceInitTests;
+struct LogFileRotationTests;
 
 namespace util {
 
@@ -229,6 +230,7 @@ class LogServiceState {
 protected:
     friend struct ::LogServiceInitTests;
     friend class ::LoggerFixture;
+    friend struct ::LogFileRotationTests;
     friend class Logger;
     friend class ::util::impl::OnAssert;
 
@@ -388,11 +390,14 @@ private:
         expected<std::vector<std::shared_ptr<spdlog::sinks::sink>>, std::string>
         getSinks(config::ClioConfigDefinition const& config);
 
+    struct RotationParams {
+        uint32_t sizeMB;
+        uint32_t maxFiles;
+    };
+
     struct FileLoggingParams {
         std::string logDir;
-
-        uint32_t rotationSizeMB;
-        uint32_t dirMaxFiles;
+        std::optional<RotationParams> rotation;  ///< nullopt when rotation is disabled
     };
 
     friend struct ::BenchmarkLoggingInitializer;