init: don't ignore errors

containers/container.go

@@ -1024,6 +1024,7 @@ func (c *Container) revalidateListens(now time.Time, actualListens map[netaddr.I
 		for pid := range c.processes {
 			fds, err := proc.ReadFds(pid)
 			if err != nil {
+				klog.Warningln(err)
 				continue
 			}
 			for _, fd := range fds {

ebpftracer/init.go

@@ -23,17 +23,18 @@ func readFds(pids []uint32) (files []file, socks []sock) {
 	for _, pid := range pids {
 		ns, err := proc.GetNetNs(pid)
 		if err != nil {
+			klog.Warningf("failed to get net ns for %d: %s", pid, err)
 			continue
 		}
 		nsId := ns.UniqueId()
 		sockets, ok := nss[nsId]
 		_ = ns.Close()
 		if !ok {
-			sockets = map[string]sock{}
-			nss[nsId] = sockets
 			if ss, err := proc.GetSockets(pid); err != nil {
-				klog.Warningln(err)
+				klog.Warningf("failed to get sockets for %d: %s", pid, err)
 			} else {
+				sockets = map[string]sock{}
+				nss[nsId] = sockets
 				for _, s := range ss {
 					sockets[s.Inode] = sock{Sock: s}
 				}
@@ -42,6 +43,7 @@ func readFds(pids []uint32) (files []file, socks []sock) {
 
 		fds, err := proc.ReadFds(pid)
 		if err != nil {
+			klog.Warningf("failed to read fds for %d: %s", pid, err)
 			continue
 		}
 		for _, fd := range fds {

proc/fd.go

@@ -5,6 +5,8 @@ import (
 	"path"
 	"strconv"
 	"strings"
+
+	"k8s.io/klog/v2"
 )
 
 type Fd struct {
@@ -18,16 +20,23 @@ func ReadFds(pid uint32) ([]Fd, error) {
 	fdDir := Path(pid, "fd")
 	entries, err := os.ReadDir(fdDir)
 	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
 		return nil, err
 	}
 	res := make([]Fd, 0, len(entries))
 	for _, entry := range entries {
 		fd, err := strconv.ParseUint(entry.Name(), 10, 64)
 		if err != nil {
+			klog.Warningf("failed to parse fd '%s': %s", entry.Name(), err)
 			continue
 		}
 		dest, err := os.Readlink(path.Join(fdDir, entry.Name()))
 		if err != nil {
+			if os.IsNotExist(err) {
+				klog.Warningf("failed to read link '%s': %s", entry.Name(), err)
+			}
 			continue
 		}
 		var socketInode string

proc/net.go

@@ -39,6 +39,9 @@ func GetSockets(pid uint32) ([]Sock, error) {
 func readSockets(src string) ([]Sock, error) {
 	f, err := os.Open(src)
 	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
 		return nil, err
 	}
 	defer f.Close()