1 files changed, 84 insertions, 0 deletions
diff --git a/library/cpp/logger/deploy/backend.cpp b/library/cpp/logger/deploy/backend.cpp
new file mode 100644
index 00000000000..4cd700c8080
--- /dev/null
+++ b/library/cpp/logger/deploy/backend.cpp
@@ -0,0 +1,84 @@
+#include "backend.h"
+
+#include <library/cpp/json/writer/json.h>
+
+#include <util/datetime/base.h>
+#include <util/generic/algorithm.h>
+#include <util/generic/hash.h>
+#include <util/string/cast.h>
+
+namespace {
+    // Keys with dedicated root getters in Unified Agent PayloadAttributesProvider
+    // (logbroker/unified_agent/plugins/yd_module/lib/attributes.*).
+    bool IsTopLevelMetaKey(TStringBuf key) noexcept {
+        return EqualToOneOf(
+            key,
+            "request_id",
+            "user_id",
+            "stackTrace",
+            "threadName");
+    }
+} // namespace
+
+TString FormatDeployJsonLogRecord(const TLogRecord& rec, TStringBuf loggerName) {
+    NJsonWriter::TBuf buf;
+    buf.BeginObject();
+    buf.WriteKey("@timestamp").WriteString(TInstant::Now().ToString());
+    buf.WriteKey("levelStr").WriteString(ToString(rec.Priority));
+
+    TStringBuf message(rec.Data, rec.Len);
+    message.ChopSuffix(TStringBuf("\n"));
+    buf.WriteKey("message").WriteString(message);
+
+    if (loggerName) {
+        buf.WriteKey("loggerName").WriteString(loggerName);
+    }
+
+    // TLogElement::With appends MetaFlags, so keys may repeat; last value wins.
+    THashMap<TStringBuf, TStringBuf> meta;
+    for (const auto& [key, value] : rec.MetaFlags) {
+        meta[key] = value;
+    }
+
+    for (const auto& [key, value] : meta) {
+        if (IsTopLevelMetaKey(key)) {
+            buf.WriteKey(key).WriteString(value);
+        }
+    }
+
+    bool openedFields = false;
+    for (const auto& [key, value] : meta) {
+        if (key == "loggerName" || IsTopLevelMetaKey(key)) {
+            continue;
+        }
+        if (!openedFields) {
+            buf.WriteKey("@fields");
+            buf.BeginObject();
+            openedFields = true;
+        }
+        buf.WriteKey(key).WriteString(value);
+    }
+    if (openedFields) {
+        buf.EndObject();
+    }
+
+    buf.EndObject();
+    return buf.Str() + '\n';
+}
+
+TDeployJsonLogBackend::TDeployJsonLogBackend(
+    THolder<TLogBackend> slave,
+    TString loggerName)
+    : Slave_(std::move(slave))
+    , LoggerName_(std::move(loggerName))
+{
+}
+
+void TDeployJsonLogBackend::WriteData(const TLogRecord& rec) {
+    const TString formatted = FormatDeployJsonLogRecord(rec, LoggerName_);
+    Slave_->WriteData(TLogRecord(rec.Priority, formatted.data(), formatted.size()));
+}
+
+void TDeployJsonLogBackend::ReopenLog() {
+    Slave_->ReopenLog();
+}