feat: update VolumeGroup utility

- Add option to list all PVs
- Add helper to get, delete, extend VG
- Add helper to delete PV

Signed-off-by: Santosh Pillai <sapillai@redhat.com>

pkg/vgmanager/lvm.go

@@ -23,33 +23,207 @@ import (
 	"github.com/red-hat-storage/lvm-operator/pkg/internal"
 )
 
+type lvmError string
+
+func (s lvmError) Error() string { return string(s) }
+
+var (
+	ErrVolumeGroupNotFound = lvmError("volume group not found")
+)
+
 const (
-	lvmPath = "/usr/sbin/lvm"
+	lvmCmd      = "/usr/sbin/lvm"
+	vgCreateCmd = "/usr/sbin/vgcreate"
+	vgExtendCmd = "/usr/sbin/vgextend"
+	vgRemoveCmd = "/usr/sbin/vgremove"
+	pvRemoveCmd = "/usr/sbin/pvremove"
 )
 
+// vgsOutput represents the output of the `vgs --reportformat json` command
+type vgsOutput struct {
+	Report []struct {
+		Vg []struct {
+			Name string `json:"vg_name"`
+		} `json:"vg"`
+	} `json:"report"`
+}
+
+// pvsOutput represents the output of the `pvs --reportformat json` command
+type pvsOutput struct {
+	Report []struct {
+		Pv []struct {
+			Name   string `json:"pv_name"`
+			VgName string `json:"vg_name"`
+		} `json:"pv"`
+	} `json:"report"`
+}
+
 // VolumeGroup represents a volume group of linux lvm.
 type VolumeGroup struct {
+	// Name is the name of the volume group
 	Name string `json:"vg_name"`
+
+	// PVs is the list of physical volumes associated with the volume group
+	PVs []string `json:"pvs"`
 }
 
-// ListVolumeGroups lists all volume groups.
-func ListVolumeGroups(exec internal.Executor) ([]VolumeGroup, error) {
-	// volumeGroupMap type is used for marshalling the `vgs --reportformt json` command output
-	// Sample output:
-	// `{"report": [ {"vg": [{"vg_name":"fedora", "pv_count":"1", "lv_count":"3", "snap_count":"0", "vg_attr":"wz--n-", "vg_size":"<475.94g", "vg_free":"0 "}]}]`
-	volumeGroupMap := map[string][]map[string][]VolumeGroup{}
-	arg := []string{
+// Create creates a new volume group
+func (vg VolumeGroup) Create(exec internal.Executor, pvs []string) error {
+	if vg.Name == "" {
+		return fmt.Errorf("failed to create volume group. Volume group name is empty")
+	}
+
+	if len(pvs) == 0 {
+		return fmt.Errorf("failed to create volume group. Physical volume list is empty")
+	}
+
+	args := []string{vg.Name}
+	args = append(args, pvs...)
+
+	_, err := exec.ExecuteCommandWithOutputAsHost(vgCreateCmd, args...)
+	if err != nil {
+		return fmt.Errorf("failed to create volume group %q. %v", vg.Name, err)
+	}
+
+	return nil
+}
+
+// Extend extends the volume group only if new physical volumes are available
+func (vg VolumeGroup) Extend(exec internal.Executor, pvs []string) error {
+	if vg.Name == "" {
+		return fmt.Errorf("failed to extend volume group. Volume group name is empty")
+	}
+
+	if len(pvs) == 0 {
+		return fmt.Errorf("failed to extend volume group. Physical volume list is empty")
+	}
+
+	args := []string{vg.Name}
+	args = append(args, pvs...)
+
+	_, err := exec.ExecuteCommandWithOutputAsHost(vgExtendCmd, args...)
+	if err != nil {
+		return fmt.Errorf("failed to extend volume group %q. %v", vg.Name, err)
+	}
+
+	return nil
+}
+
+// Delete deletes a volume group and the physical volumes associated with it
+func (vg VolumeGroup) Delete(exec internal.Executor) error {
+	// Remove Volume Group
+	vgArgs := []string{vg.Name, "--nolock"}
+	_, err := exec.ExecuteCommandWithOutputAsHost(vgRemoveCmd, vgArgs...)
+	if err != nil {
+		return fmt.Errorf("failed to remove volume group %q. %v", vg.Name, err)
+	}
+
+	// Remove physical volumes
+	pvArgs := append(vg.PVs, "--nolock")
+	_, err = exec.ExecuteCommandWithOutputAsHost(pvRemoveCmd, pvArgs...)
+	if err != nil {
+		return fmt.Errorf("failed to remove physical volumes for the volume group %q. %v", vg.Name, err)
+	}
+	return nil
+}
+
+// GetVolumeGroup returns a volume group along with the associated physical volumes
+func GetVolumeGroup(exec internal.Executor, name string) (*VolumeGroup, error) {
+	res := new(vgsOutput)
+
+	// TODO: Check if `vgs <vg_name> --reportformat json` can be used to filter out the exact volume group name.
+	args := []string{
 		"vgs", "--reportformat", "json",
 	}
-	output, err := exec.ExecuteCommandWithOutputAsHost(lvmPath, arg...)
+	if err := execute(exec, res, args...); err != nil {
+		return nil, fmt.Errorf("failed to list volume groups. %v", err)
+	}
+
+	vgFound := false
+	volumeGroup := &VolumeGroup{}
+	for _, report := range res.Report {
+		for _, vg := range report.Vg {
+			if vg.Name == name {
+				volumeGroup.Name = vg.Name
+				vgFound = true
+				break
+			}
+		}
+	}
+
+	if !vgFound {
+		return nil, ErrVolumeGroupNotFound
+	}
+
+	// Get Physical Volumes associated with the Volume Group
+	pvs, err := ListPhysicalVolumes(exec, name)
 	if err != nil {
+		return nil, fmt.Errorf("failed to list physical volumes for volume group %q. %v", name, err)
+	}
+
+	volumeGroup.PVs = pvs
+	return volumeGroup, nil
+}
+
+// ListPhysicalVolumes returns list of physical volumes used to create the given volume group
+func ListPhysicalVolumes(exec internal.Executor, vgName string) ([]string, error) {
+	res := new(pvsOutput)
+	args := []string{
+		"pvs", "-S", fmt.Sprintf("vgname=%s", vgName), "--reportformat", "json",
+	}
+	if err := execute(exec, res, args...); err != nil {
+		return []string{}, err
+	}
+
+	pvs := []string{}
+	for _, report := range res.Report {
+		for _, pv := range report.Pv {
+			pvs = append(pvs, pv.Name)
+		}
+	}
+	return pvs, nil
+}
+
+// ListVolumeGroups lists all volume groups and the physical volumes associated with them.
+func ListVolumeGroups(exec internal.Executor) ([]VolumeGroup, error) {
+	res := new(vgsOutput)
+	args := []string{
+		"vgs", "--reportformat", "json",
+	}
+
+	if err := execute(exec, res, args...); err != nil {
 		return nil, fmt.Errorf("failed to list volume groups. %v", err)
 	}
 
-	err = json.Unmarshal([]byte(output), &volumeGroupMap)
+	vgList := []VolumeGroup{}
+	for _, report := range res.Report {
+		for _, vg := range report.Vg {
+			vgList = append(vgList, VolumeGroup{Name: vg.Name, PVs: []string{}})
+		}
+	}
+
+	// Get Physical Volumes associated with the Volume Group
+	for i, vg := range vgList {
+		pvs, err := ListPhysicalVolumes(exec, vg.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to list physical volumes for volume group %q. %v", vg.Name, err)
+		}
+		vgList[i].PVs = pvs
+	}
+
+	return vgList, nil
+}
+
+func execute(exec internal.Executor, v interface{}, args ...string) error {
+	output, err := exec.ExecuteCommandWithOutputAsHost(lvmCmd, args...)
+	if err != nil {
+		return fmt.Errorf("failed to execute command. %v", err)
+	}
+
+	err = json.Unmarshal([]byte(output), &v)
 	if err != nil {
-		return nil, fmt.Errorf("failed to unmarshal volume group response. %v", err)
+		return fmt.Errorf("failed to unmarshal response. %v", err)
 	}
 
-	return volumeGroupMap["report"][0]["vg"], nil
+	return nil
 }