util: add support for the nsenter

add support to run rbd map and mount -t
commands with the nsenter.

complete design of pod/multus network
is added here https://github.com/rook/rook/
blob/master/design/ceph/multus-network.md#csi-pods

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

internal/util/cephcmds.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os"
 	"os/exec"
 	"time"
 
@@ -32,6 +33,47 @@ import (
 // InvalidPoolID used to denote an invalid pool.
 const InvalidPoolID int64 = -1
 
+// ExecuteCommandWithNSEnter executes passed in program with args with nsenter
+// and returns separate stdout and stderr streams. In case ctx is not set to
+// context.TODO(), the command will be logged after it was executed.
+func ExecuteCommandWithNSEnter(ctx context.Context, netPath, program string, args ...string) (string, string, error) {
+	var (
+		sanitizedArgs = StripSecretInArgs(args)
+		stdoutBuf     bytes.Buffer
+		stderrBuf     bytes.Buffer
+	)
+
+	// check netPath exists
+	if _, err := os.Stat(netPath); err != nil {
+		return "", "", fmt.Errorf("failed to get stat for %s %w", netPath, err)
+	}
+	//  nsenter --net=%s -- <program> <args>
+	args = append([]string{fmt.Sprintf("--net=%s", netPath), "--", program}, args...)
+	cmd := exec.Command("nsenter", args...) // #nosec:G204, commands executing not vulnerable.
+
+	cmd.Stdout = &stdoutBuf
+	cmd.Stderr = &stderrBuf
+
+	err := cmd.Run()
+	stdout := stdoutBuf.String()
+	stderr := stderrBuf.String()
+
+	if err != nil {
+		err = fmt.Errorf("an error (%w) occurred while running %s args: %v", err, program, sanitizedArgs)
+		if ctx != context.TODO() {
+			log.UsefulLog(ctx, "%s", err)
+		}
+
+		return stdout, stderr, err
+	}
+
+	if ctx != context.TODO() {
+		log.UsefulLog(ctx, "command succeeded: %s %v", program, sanitizedArgs)
+	}
+
+	return stdout, stderr, nil
+}
+
 // ExecCommand executes passed in program with args and returns separate stdout
 // and stderr streams. In case ctx is not set to context.TODO(), the command
 // will be logged after it was executed.

internal/util/csiconfig.go

@@ -49,6 +49,8 @@ type ClusterInfo struct {
 		// SubvolumeGroup contains the name of the SubvolumeGroup for CSI volumes
 		SubvolumeGroup string `json:"subvolumeGroup"`
 	} `json:"cephFS"`
+	// symlink filepath for the network namespace where we need to execute commands.
+	NetNamespaceFilePath string `json:"netNamespaceFilePath"`
 }
 
 // Expected JSON structure in the passed in config file is,
@@ -161,3 +163,12 @@ func GetClusterID(options map[string]string) (string, error) {
 
 	return clusterID, nil
 }
+
+func GetNetNamespaceFilePath(pathToConfig, clusterID string) (string, error) {
+	cluster, err := readClusterInfo(pathToConfig, clusterID)
+	if err != nil {
+		return "", err
+	}
+
+	return cluster.NetNamespaceFilePath, nil
+}

internal/util/csiconfig_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package util
 
 import (
+	"encoding/json"
 	"os"
 	"testing"
 )
@@ -138,3 +139,69 @@ func TestCSIConfig(t *testing.T) {
 		t.Errorf("Test setup error %s", err)
 	}
 }
+
+func TestGetNetNamespaceFilePath(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name      string
+		clusterID string
+		want      string
+	}{
+		{
+			name:      "get NetNamespaceFilePath for cluster-1",
+			clusterID: "cluster-1",
+			want:      "/var/lib/kubelet/plugins/rbd.ceph.csi.com/cluster1-net",
+		},
+		{
+			name:      "get NetNamespaceFilePath for cluster-2",
+			clusterID: "cluster-2",
+			want:      "/var/lib/kubelet/plugins/rbd.ceph.csi.com/cluster2-net",
+		},
+		{
+			name:      "when NetNamespaceFilePath is empty",
+			clusterID: "cluster-3",
+			want:      "",
+		},
+	}
+
+	csiConfig := []ClusterInfo{
+		{
+			ClusterID:            "cluster-1",
+			Monitors:             []string{"ip-1", "ip-2"},
+			NetNamespaceFilePath: "/var/lib/kubelet/plugins/rbd.ceph.csi.com/cluster1-net",
+		},
+		{
+			ClusterID:            "cluster-2",
+			Monitors:             []string{"ip-3", "ip-4"},
+			NetNamespaceFilePath: "/var/lib/kubelet/plugins/rbd.ceph.csi.com/cluster2-net",
+		},
+		{
+			ClusterID: "cluster-3",
+			Monitors:  []string{"ip-5", "ip-6"},
+		},
+	}
+	csiConfigFileContent, err := json.Marshal(csiConfig)
+	if err != nil {
+		t.Errorf("failed to marshal csi config info %v", err)
+	}
+	tmpConfPath := t.TempDir() + "/ceph-csi.json"
+	err = os.WriteFile(tmpConfPath, csiConfigFileContent, 0o600)
+	if err != nil {
+		t.Errorf("failed to write %s file content: %v", CsiConfigFile, err)
+	}
+	for _, tt := range tests {
+		ts := tt
+		t.Run(ts.name, func(t *testing.T) {
+			t.Parallel()
+			got, err := GetNetNamespaceFilePath(tmpConfPath, ts.clusterID)
+			if err != nil {
+				t.Errorf("GetNetNamespaceFilePath() error = %v", err)
+
+				return
+			}
+			if got != ts.want {
+				t.Errorf("GetNetNamespaceFilePath() = %v, want %v", got, ts.want)
+			}
+		})
+	}
+}