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refactor(lvm): continue refactoring of lvm command calling convention (…
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…#261)

* refactor(ci): rename env variables and update vgcreate command

Env vars LVM_SYSTEMID and LVM_CONFIG are used to describe a potentially
foreign lvm system on the kubernetes host. The lvm system is only meant
to be foreign to the lvm-localpv containers.

Due to the way the ci tests are written, the kubernetes host and the
lvm-localpv conatiners must have identical lvm configurations or ci
tests might fail.

The variables LVM_SYSTEMID and LVM_CONFIG have been renamed to
FOREIGN_LVM_SYSTEMID and FOREIGN_LVM_CONFIG, respectively. This is
helpful when determining their roles at a glance.

A secondary change was made to the foreign pv creation: the lvm option
`--config` has been used in place of `--systemid` to hopefully minimize
unintended side effects of using the same lvm config (with the exception
of the system id) during volume group creation.

Signed-off-by: kro <[email protected]>

* refactor(lvm): update all lvm commands to use split output

The LVM system may sometimes produce non-critical warnings which are
written to STDERR without formatting. Combining STDERR with STDIN may
cause failures when the output is being formatted or otherwise
interpreted.

Following pull #250, it's been requested that all lvm commands be
refactored to use a split output in order to resolve this issue under
non-tested scenarios. See issue #247.

The definition for RunCommandSplit has been moved above all uses of the
function, and any Command using CombinedOutput and an lvm command (s.a.:
lvs, vgs, lvcreate, &c.) has been refactored to instead use
RunCommandSplit to obtain the command's output.

If anything is written to STDERR by the lvm commands, RunCommandSplit
prints the message to the log as a warning.

Signed-off-by: kro <[email protected]>

---------

Signed-off-by: kro <[email protected]>
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@kro-cat
kro-cat authored Oct 18, 2023
1 parent 9a7388f commit 9e0ac5b
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Showing 2 changed files with 42 additions and 50 deletions.
10 changes: 5 additions & 5 deletions ci/ci-test.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,9 +29,9 @@ then
export KUBECONFIG="${HOME}/.kube/config"
fi

# systemid for the testing environment. The kubernetes host machine will serve as the foreign lvm system.
LVM_SYSTEMID="openebs-ci-test-system"
LVM_CONFIG="global{system_id_source=lvmlocal}local{system_id=${LVM_SYSTEMID}}"
# foreign systemid for the testing environment.
FOREIGN_LVM_SYSTEMID="openebs-ci-test-system"
FOREIGN_LVM_CONFIG="global{system_id_source=lvmlocal}local{system_id=${FOREIGN_LVM_SYSTEMID}}"

# Clean up generated resources for successive tests.
cleanup_loopdev() {
Expand All @@ -54,7 +54,7 @@ cleanup_lvmvg() {
cleanup_foreign_lvmvg() {
if [ -f /tmp/openebs_ci_foreign_disk.img ]
then
sudo vgremove foreign_lvmvg --config="${LVM_CONFIG}" -y || true
sudo vgremove foreign_lvmvg --config="${FOREIGN_LVM_CONFIG}" -y || true
rm /tmp/openebs_ci_foreign_disk.img
fi
cleanup_loopdev
Expand Down Expand Up @@ -91,7 +91,7 @@ cleanup_foreign_lvmvg
truncate -s 1024G /tmp/openebs_ci_foreign_disk.img
foreign_disk="$(sudo losetup -f /tmp/openebs_ci_foreign_disk.img --show)"
sudo pvcreate "${foreign_disk}"
sudo vgcreate foreign_lvmvg "${foreign_disk}" --systemid="${LVM_SYSTEMID}"
sudo vgcreate foreign_lvmvg "${foreign_disk}" --config="${FOREIGN_LVM_CONFIG}"

# install snapshot and thin volume module for lvm
sudo modprobe dm-snapshot
Expand Down
82 changes: 37 additions & 45 deletions pkg/lvm/lvm_util.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,27 @@ func buildLVMDestroyArgs(vol *apis.LVMVolume) []string {
return LVMVolArg
}

// RunCommandSplit is a wrapper function to run a command and receive its
// STDERR and STDOUT streams in separate []byte vars.
func RunCommandSplit(command string, args ...string) ([]byte, []byte, error) {
var cmdStdout bytes.Buffer
var cmdStderr bytes.Buffer

cmd := exec.Command(command, args...)
cmd.Stdout = &cmdStdout
cmd.Stderr = &cmdStderr
err := cmd.Run()

output := cmdStdout.Bytes()
error_output := cmdStderr.Bytes()

if len(error_output) > 0 {
klog.Warningf("lvm: said into stderr: %s", error_output)
}

return output, error_output, err
}

// CreateVolume creates the lvm volume
func CreateVolume(vol *apis.LVMVolume) error {
volume := vol.Spec.VolGroup + "/" + vol.Name
Expand All @@ -275,8 +296,7 @@ func CreateVolume(vol *apis.LVMVolume) error {
}

args := buildLVMCreateArgs(vol)
cmd := exec.Command(LVCreate, args...)
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit(LVCreate, args...)

if err != nil {
err = newExecError(out, err)
Expand Down Expand Up @@ -314,8 +334,7 @@ func DestroyVolume(vol *apis.LVMVolume) error {
}

args := buildLVMDestroyArgs(vol)
cmd := exec.Command(LVRemove, args...)
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit(LVRemove, args...)

if err != nil {
klog.Errorf(
Expand Down Expand Up @@ -406,8 +425,7 @@ func ResizeLVMVolume(vol *apis.LVMVolume, resizefs bool) error {
volume := vol.Spec.VolGroup + "/" + vol.Name

args := buildVolumeResizeArgs(vol, resizefs)
cmd := exec.Command(LVExtend, args...)
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit(LVExtend, args...)

if err != nil {
klog.Errorf(
Expand All @@ -430,8 +448,7 @@ func getLVSize(vol *apis.LVMVolume) (uint64, error) {
"--nosuffix",
}

cmd := exec.Command(LVList, args...)
raw, err := cmd.CombinedOutput()
raw, _, err := RunCommandSplit(LVList, args...)
if err != nil {
return 0, errors.Wrapf(
err,
Expand Down Expand Up @@ -495,8 +512,7 @@ func CreateSnapshot(snap *apis.LVMSnapshot) error {
snapVolume := snap.Spec.VolGroup + "/" + getLVMSnapName(snap.Name)

args := buildLVMSnapCreateArgs(snap)
cmd := exec.Command(LVCreate, args...)
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit(LVCreate, args...)

if err != nil {
klog.Errorf("lvm: could not create snapshot %s cmd %v error: %s", snapVolume, args, string(out))
Expand Down Expand Up @@ -524,8 +540,7 @@ func DestroySnapshot(snap *apis.LVMSnapshot) error {
}

args := buildLVMSnapDestroyArgs(snap)
cmd := exec.Command(LVRemove, args...)
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit(LVRemove, args...)

if err != nil {
klog.Errorf("lvm: could not remove snapshot %s cmd %v error: %s", snapVolume, args, string(out))
Expand Down Expand Up @@ -639,34 +654,13 @@ func getIntFieldValue(fieldName, fieldValue string) int {
// serving vgs or other lvm utility.
func ReloadLVMMetadataCache() error {
args := []string{"--cache"}
cmd := exec.Command(PVScan, args...)
output, err := cmd.CombinedOutput()
output, _, err := RunCommandSplit(PVScan, args...)
if err != nil {
klog.Errorf("lvm: reload lvm metadata cache: %v - %v", string(output), err)
return err
}
return nil
}

// RunCommandSplit is a wrapper function to run a command and receive its
// STDERR and STDOUT streams in separate []byte vars.
func RunCommandSplit(command string, args ...string) ([]byte, []byte, error) {
var cmdStdout bytes.Buffer
var cmdStderr bytes.Buffer

cmd := exec.Command(command, args...)
cmd.Stdout = &cmdStdout
cmd.Stderr = &cmdStderr
err := cmd.Run()

output := cmdStdout.Bytes()
error_output := cmdStderr.Bytes()

if len(error_output) > 0 {
klog.Warningf("lvm: said into stderr: %s", error_output)
}

return output, error_output, err
return nil
}

// ListLVMVolumeGroup invokes `vgs` to list all the available volume
Expand Down Expand Up @@ -880,12 +874,12 @@ func ListLVMLogicalVolume() ([]LogicalVolume, error) {
"--reportformat", "json",
"--units", "b",
}
cmd := exec.Command(LVList, args...)
output, err := cmd.CombinedOutput()
output, _, err := RunCommandSplit(LVList, args...)
if err != nil {
klog.Errorf("lvm: error while running command %s %v: %v", LVList, args, err)
return nil, err
}

return decodeLvsJSON(output)
}

Expand All @@ -902,12 +896,12 @@ func ListLVMPhysicalVolume() ([]PhysicalVolume, error) {
"--reportformat", "json",
"--units", "b",
}
cmd := exec.Command(PVList, args...)
output, err := cmd.CombinedOutput()
output, _, err := RunCommandSplit(PVList, args...)
if err != nil {
klog.Errorf("lvm: error while running command %s %v: %v", PVList, args, err)
return nil, err
}

return decodePvsJSON(output)
}

Expand Down Expand Up @@ -1029,20 +1023,19 @@ func decodePvsJSON(raw []byte) ([]PhysicalVolume, error) {

// lvThinExists verifies if thin pool/volume already exists for given volumegroup
func lvThinExists(vg string, name string) bool {
cmd := exec.Command("lvs", vg+"/"+name, "--noheadings", "-o", "lv_name")
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit("lvs", vg+"/"+name, "--noheadings", "-o", "lv_name")
if err != nil {
klog.Errorf("failed to list existing volumes:%v", err)
return false
}

return name == strings.TrimSpace(string(out))
}

// snapshotExists checks if a snapshot volume exists for the given volumegroup
// and snapshot name.
func isSnapshotExists(vg, snapVolumeName string) (bool, error) {
cmd := exec.Command("lvs", vg+"/"+snapVolumeName, "--noheadings", "-o", "lv_name")
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit("lvs", vg+"/"+snapVolumeName, "--noheadings", "-o", "lv_name")
if err != nil {
return false, err
}
Expand All @@ -1051,8 +1044,7 @@ func isSnapshotExists(vg, snapVolumeName string) (bool, error) {

// getVGSize get the size in bytes for given volumegroup name
func getVGSize(vgname string) string {
cmd := exec.Command("vgs", vgname, "--noheadings", "-o", "vg_free", "--units", "b", "--nosuffix")
out, err := cmd.CombinedOutput()
out, _, err := RunCommandSplit("vgs", vgname, "--noheadings", "-o", "vg_free", "--units", "b", "--nosuffix")
if err != nil {
klog.Errorf("failed to list existing volumegroup:%v , %v", vgname, err)
return ""
Expand Down

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