fix(proxy): read RSS from /proc when psutil is missing so the release image reports memory

The release image installs only the proxy extras, and psutil is a locust and mirakuru dev
dependency, so /debug/memory/summary answered with an error and no ram_usage_mb on the e2e
gate. Fall back to /proc/self/statm and /proc/meminfo on Linux when psutil cannot be imported

litellm/proxy/common_utils/debug_utils.py

@@ -233,6 +233,80 @@ def _process_memory_usage(process: _ProcessHandle) -> _ProcessMemoryUsage:
     )
 
 
+PROC_STATM_PATH: Final = "/proc/self/statm"
+PROC_MEMINFO_PATH: Final = "/proc/meminfo"
+PSUTIL_MISSING_ERROR: Final = "Install psutil for memory monitoring: pip install psutil"
+
+
+class _ProcMemoryInfo(NamedTuple):
+    rss: int
+    vms: int
+
+
+class _ProcFilesystemProcess:
+    """Memory of the running process read from the Linux proc filesystem, for images without psutil."""
+
+    def __init__(
+        self,
+        statm_path: str = PROC_STATM_PATH,
+        meminfo_path: str = PROC_MEMINFO_PATH,
+        page_size: int | None = None,
+    ) -> None:
+        self._statm_path: Final = statm_path
+        self._meminfo_path: Final = meminfo_path
+        self._page_size: Final = os.sysconf("SC_PAGE_SIZE") if page_size is None else page_size
+
+    def memory_info(self) -> _ProcMemoryInfo:
+        with open(self._statm_path, encoding="ascii") as statm:
+            size_pages, resident_pages = statm.read().split()[:2]
+        return _ProcMemoryInfo(rss=int(resident_pages) * self._page_size, vms=int(size_pages) * self._page_size)
+
+    def memory_percent(self) -> float:
+        with open(self._meminfo_path, encoding="ascii") as meminfo:
+            total_kilobytes: Final = next(int(line.split()[1]) for line in meminfo if line.startswith("MemTotal:"))
+        return self.memory_info().rss / (total_kilobytes * 1024) * 100
+
+
+def _process_handle() -> _ProcessHandle | None:
+    try:
+        import psutil
+    except ImportError:
+        return _ProcFilesystemProcess() if os.path.exists(PROC_STATM_PATH) else None
+    return psutil.Process()
+
+
+def _health_status(memory_percent: float) -> str:
+    if memory_percent > 80:
+        return "critical"
+    if memory_percent > 60:
+        return "warning"
+    return "healthy"
+
+
+class _SummaryProcessMemory(TypedDict, total=False):
+    summary: ReadOnly[str]
+    ram_usage_mb: ReadOnly[float]
+    system_memory_percent: ReadOnly[float]
+    error: ReadOnly[str]
+
+
+def _summary_process_memory(process: _ProcessHandle | None) -> tuple[_SummaryProcessMemory, str]:
+    if process is None:
+        missing: Final[_SummaryProcessMemory] = {"error": PSUTIL_MISSING_ERROR}
+        return missing, "healthy"
+    try:
+        usage: Final = _process_memory_usage(process)
+    except Exception as e:
+        unreadable: Final[_SummaryProcessMemory] = {"error": str(e)}
+        return unreadable, "healthy"
+    memory: Final[_SummaryProcessMemory] = {
+        "summary": f"{usage.resident_megabytes:.1f} MB ({usage.percent:.1f}% of system memory)",
+        "ram_usage_mb": round(usage.resident_megabytes, 2),
+        "system_memory_percent": round(usage.percent, 2),
+    }
+    return memory, _health_status(usage.percent)
+
+
 @router.get("/debug/memory/summary", include_in_schema=False)
 async def get_memory_summary(
     _: UserAPIKeyAuth = Depends(user_api_key_auth),
@@ -260,35 +334,7 @@ async def get_memory_summary(
         user_api_key_cache,
     )
 
-    # Get process memory info
-    process_memory = {}
-    health_status = "healthy"
-
-    try:
-        import psutil
-
-        usage: Final = _process_memory_usage(psutil.Process())
-        memory_mb: Final = usage.resident_megabytes
-        memory_percent: Final = usage.percent
-
-        process_memory = {
-            "summary": f"{memory_mb:.1f} MB ({memory_percent:.1f}% of system memory)",
-            "ram_usage_mb": round(memory_mb, 2),
-            "system_memory_percent": round(memory_percent, 2),
-        }
-
-        # Check memory health status
-        if memory_percent > 80:
-            health_status = "critical"
-        elif memory_percent > 60:
-            health_status = "warning"
-        else:
-            health_status = "healthy"
-
-    except ImportError:
-        process_memory["error"] = "Install psutil for memory monitoring: pip install psutil"
-    except Exception as e:
-        process_memory["error"] = str(e)
+    process_memory, health_status = _summary_process_memory(_process_handle())
 
     # Get cache information
     caches: Final[dict[str, object]] = {}

tests/test_litellm/proxy/common_utils/test_debug_utils.py

@@ -1,10 +1,63 @@
 import os
 import socket
+from pathlib import Path
 
 import pytest
 
 from litellm.proxy._types import UserAPIKeyAuth
-from litellm.proxy.common_utils.debug_utils import get_memory_summary
+from litellm.proxy.common_utils.debug_utils import (
+    PSUTIL_MISSING_ERROR,
+    _ProcFilesystemProcess,
+    _summary_process_memory,
+    get_memory_summary,
+)
+
+PAGE_SIZE = 4096
+STATM_SIZE_PAGES = 100_000
+STATM_RESIDENT_PAGES = 30_000
+MEMINFO_TOTAL_KB = 1_000_000
+
+
+@pytest.fixture
+def proc_process(tmp_path: Path) -> _ProcFilesystemProcess:
+    statm = tmp_path / "statm"
+    statm.write_text(f"{STATM_SIZE_PAGES} {STATM_RESIDENT_PAGES} 5000 1 0 20000 0\n")
+    meminfo = tmp_path / "meminfo"
+    meminfo.write_text(
+        f"MemTotal:       {MEMINFO_TOTAL_KB} kB\nMemFree:         400000 kB\nMemAvailable:    600000 kB\n"
+    )
+    return _ProcFilesystemProcess(statm_path=str(statm), meminfo_path=str(meminfo), page_size=PAGE_SIZE)
+
+
+def test_proc_filesystem_process_reads_resident_and_virtual_bytes_from_statm(
+    proc_process: _ProcFilesystemProcess,
+) -> None:
+    memory_info = proc_process.memory_info()
+
+    assert memory_info.rss == STATM_RESIDENT_PAGES * PAGE_SIZE
+    assert memory_info.vms == STATM_SIZE_PAGES * PAGE_SIZE
+
+
+def test_proc_filesystem_process_reports_share_of_meminfo_total(proc_process: _ProcFilesystemProcess) -> None:
+    expected_percent = STATM_RESIDENT_PAGES * PAGE_SIZE / (MEMINFO_TOTAL_KB * 1024) * 100
+
+    assert proc_process.memory_percent() == pytest.approx(expected_percent)
+
+
+def test_summary_reports_rss_from_the_proc_filesystem(proc_process: _ProcFilesystemProcess) -> None:
+    memory, health_status = _summary_process_memory(proc_process)
+
+    assert memory["ram_usage_mb"] == round(STATM_RESIDENT_PAGES * PAGE_SIZE / (1024 * 1024), 2)
+    assert memory["system_memory_percent"] == pytest.approx(12.0)
+    assert health_status == "healthy"
+    assert "error" not in memory
+
+
+def test_summary_without_any_memory_source_names_psutil_and_reports_no_rss() -> None:
+    memory, health_status = _summary_process_memory(None)
+
+    assert memory == {"error": PSUTIL_MISSING_ERROR}
+    assert health_status == "healthy"
 
 
 @pytest.mark.asyncio