CANARY (DO NOT MERGE): force userspace DNS path on + strace the fs mount

Throwaway instrumentation to validate the NFS mount end to end in a test
cluster, off the CRUSOE-70481 branch:

- userspaceDNSResolutionEnabled() forced to true, simulating the feature flag
  rolled out (the flag endpoint is not deployed in the test env, so the real
  fetch would 404 -> false).
- fs node Mounter wrapped (straceMountExec) so `mount` runs under strace,
  writing the trace to /tmp/crusoe-mount-strace-<ts>.log -- captures the
  mount(2) source/options and the connect() targets the kernel dials.
- strace added to the runtime image.

DO NOT MERGE. This branch exists only to build a canary image for e2e testing.

Author: npujari-crusoe

Dockerfile

@@ -30,6 +30,7 @@ RUN apk upgrade --no-cache && \
     apk add --no-cache e2fsprogs-extra~=1.47.0 && \
     apk add --no-cache blkid~=2.40.1 && \
     apk add --no-cache xfsprogs-extra~=6.8.0 && \
+    apk add --no-cache strace && \
     rm -rf /var/cache/apk/*
 
 COPY --from=builder /build/dist/crusoe-csi-driver /usr/local/go/bin/crusoe-csi-driver

internal/node/fs/fs_node.go

@@ -182,20 +182,14 @@ func (d *Node) fetchDiskOrNil(
 }
 
 // userspaceDNSResolutionEnabled reports whether the project has opted into
-// CSI-side NFS DNS resolution. It defaults to false (legacy behaviour) on any
-// flag-fetch error, so an unreachable or not-yet-deployed flag endpoint keeps
-// today's behaviour.
-func (d *Node) userspaceDNSResolutionEnabled(ctx context.Context) bool {
-	enabled, err := crusoe.GetUserspaceDNSResolutionFlag(
-		ctx, d.CrusoeHTTPClient, d.CrusoeAPIEndpoint, d.HostInstance.ProjectId)
-	if err != nil {
-		klog.Warningf("failed to fetch userspace-DNS-resolution flag, defaulting to legacy resolution: %s",
-			err.Error())
-
-		return false
-	}
-
-	return enabled
+// CSI-side NFS DNS resolution.
+//
+// CANARY (DO NOT MERGE): forced to true to simulate the feature flag rolled out.
+// The real implementation fetches GetUserspaceDNSResolutionFlag and defaults to
+// false on error; here the flag endpoint is not deployed in the test env, so we
+// short-circuit to exercise the userspace path end to end.
+func (d *Node) userspaceDNSResolutionEnabled(_ context.Context) bool {
+	return true
 }
 
 // legacyResolveNFSTarget reproduces the previously-released resolution exactly:

internal/server.go

@@ -85,9 +85,10 @@ func registerNode(grpcServer *grpc.Server, hostInstance *crusoeapi.InstanceV1Alp
 	case common.DiskTypeFS:
 		maxVolumesPerNode = common.MaxFSVolumesPerNode
 		nodeServer = &fs.Node{
-			CrusoeClient:      newCrusoeClientWithViperConfig(),
-			CrusoeHTTPClient:  newCrusoeHTTPClientWithViperConfig(),
-			Mounter:           mount.NewSafeFormatAndMount(mount.New(""), exec.New()),
+			CrusoeClient:     newCrusoeClientWithViperConfig(),
+			CrusoeHTTPClient: newCrusoeHTTPClientWithViperConfig(),
+			// CANARY (DO NOT MERGE): strace-wrap the fs mount for e2e validation.
+			Mounter:           mount.NewSafeFormatAndMount(mount.New(""), straceMountExec{exec.New()}),
 			Resizer:           mount.NewResizeFs(exec.New()),
 			CrusoeAPIEndpoint: viper.GetString(CrusoeAPIEndpointFlag),
 			NFSRemotePorts:    viper.GetString(NFSRemotePortsFlag),

internal/strace_mount_canary.go

@@ -0,0 +1,52 @@
+package internal
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"k8s.io/klog/v2"
+	"k8s.io/utils/exec"
+)
+
+// straceMountExec is CANARY INSTRUMENTATION — DO NOT MERGE.
+//
+// It wraps an exec.Interface so the fs node's `mount` command runs under strace,
+// writing a per-mount trace to a file. It exists only to validate the NFS mount
+// end to end during canary testing — the mount(2) source/options and the
+// connect() targets the kernel actually dials. Requires `strace` in the runtime
+// image. Non-mount commands pass through unchanged.
+type straceMountExec struct {
+	exec.Interface
+}
+
+func (e straceMountExec) Command(cmd string, args ...string) exec.Cmd {
+	if cmd == "mount" {
+		return e.Interface.Command("strace", straceMountArgs(args)...)
+	}
+
+	return e.Interface.Command(cmd, args...)
+}
+
+func (e straceMountExec) CommandContext(ctx context.Context, cmd string, args ...string) exec.Cmd {
+	if cmd == "mount" {
+		return e.Interface.CommandContext(ctx, "strace", straceMountArgs(args)...)
+	}
+
+	return e.Interface.CommandContext(ctx, cmd, args...)
+}
+
+func straceMountArgs(mountArgs []string) []string {
+	logPath := fmt.Sprintf("/tmp/crusoe-mount-strace-%d.log", time.Now().UnixNano())
+	klog.Warningf("CANARY: tracing mount under strace -> %s", logPath)
+
+	// -f follows mount.nfs forks; -tt timestamps; -s 512 keeps long mount-option
+	// strings intact; connect/sendto/sendmsg show the IPs the kernel dials.
+	straceArgs := []string{
+		"-f", "-tt", "-s", "512",
+		"-e", "trace=mount,connect,sendto,sendmsg",
+		"-o", logPath, "mount",
+	}
+
+	return append(straceArgs, mountArgs...)
+}