fix: Don't return errors or warnings for PID 0

The scheduler/idle task is not our object of interes and it has no
cgroups or namespaces, it also never can belong to any container. Just
ignore it.

crates/bpf-common/src/parsing/procfs.rs

@@ -178,6 +178,10 @@ fn get_container_id_from_cgroup(cgroup_info: &str) -> Option<ContainerId> {
 }
 
 pub fn get_process_container_id(pid: Pid) -> Result<Option<ContainerId>, ProcfsError> {
+    if pid.as_raw() == 0 {
+        return Ok(None);
+    }
+
     let path = format!("/proc/{pid}/cgroup");
     let file = File::open(&path).map_err(|source| ProcfsError::ReadFile { source, path })?;
 

crates/bpf-filtering/src/process_tree.rs

@@ -66,12 +66,14 @@ fn get_process_namespace(pid: Pid, ns_type: &str) -> Result<u32, Error> {
 fn get_process_namespace_or_log(pid: Pid, namespace_type: &str) -> u32 {
     get_process_namespace(pid, namespace_type).map_or_else(
         |e| {
-            log::warn!(
-                "Failed to determine {} namespace for process {:?}: {}",
-                namespace_type,
-                pid,
-                e
-            );
+            if pid.as_raw() != 0 {
+                log::warn!(
+                    "Failed to determine {} namespace for process {:?}: {}",
+                    namespace_type,
+                    pid,
+                    e
+                );
+            }
             u32::default()
         },
         |v| v,