open-nomad/client/allocrunner/csi_hook.go
Tim Gross 309ac6c3d8
csi: don't wait to fire initial unmount RPC (#12102)
In PR #11892 we updated the `csi_hook` to unmount the volume locally
via the CSI node RPCs before releasing the claim from the server. The
timer for this hook was initialized with the retry time, forcing us to
wait 1s before making the first unmount RPC calls.

Use the new helper for timers to ensure we clean up the timer nicely.
2022-02-22 13:43:06 -05:00

335 lines
9.2 KiB
Go

package allocrunner
import (
"context"
"fmt"
"sync"
"time"
hclog "github.com/hashicorp/go-hclog"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/nomad/client/pluginmanager/csimanager"
"github.com/hashicorp/nomad/helper"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/hashicorp/nomad/plugins/drivers"
)
// csiHook will wait for remote csi volumes to be attached to the host before
// continuing.
//
// It is a noop for allocs that do not depend on CSI Volumes.
type csiHook struct {
alloc *structs.Allocation
logger hclog.Logger
csimanager csimanager.Manager
rpcClient RPCer
taskCapabilityGetter taskCapabilityGetter
updater hookResourceSetter
nodeSecret string
volumeRequests map[string]*volumeAndRequest
maxBackoffInterval time.Duration
maxBackoffDuration time.Duration
}
// implemented by allocrunner
type taskCapabilityGetter interface {
GetTaskDriverCapabilities(string) (*drivers.Capabilities, error)
}
func newCSIHook(alloc *structs.Allocation, logger hclog.Logger, csi csimanager.Manager, rpcClient RPCer, taskCapabilityGetter taskCapabilityGetter, updater hookResourceSetter, nodeSecret string) *csiHook {
return &csiHook{
alloc: alloc,
logger: logger.Named("csi_hook"),
csimanager: csi,
rpcClient: rpcClient,
taskCapabilityGetter: taskCapabilityGetter,
updater: updater,
nodeSecret: nodeSecret,
volumeRequests: map[string]*volumeAndRequest{},
maxBackoffInterval: time.Minute,
maxBackoffDuration: time.Hour * 24,
}
}
func (c *csiHook) Name() string {
return "csi_hook"
}
func (c *csiHook) Prerun() error {
if !c.shouldRun() {
return nil
}
// We use this context only to attach hclog to the gRPC context. The
// lifetime is the lifetime of the gRPC stream, not specific RPC timeouts,
// but we manage the stream lifetime via Close in the pluginmanager.
ctx := context.Background()
volumes, err := c.claimVolumesFromAlloc()
if err != nil {
return fmt.Errorf("claim volumes: %v", err)
}
c.volumeRequests = volumes
mounts := make(map[string]*csimanager.MountInfo, len(volumes))
for alias, pair := range volumes {
mounter, err := c.csimanager.MounterForPlugin(ctx, pair.volume.PluginID)
if err != nil {
return err
}
usageOpts := &csimanager.UsageOptions{
ReadOnly: pair.request.ReadOnly,
AttachmentMode: pair.request.AttachmentMode,
AccessMode: pair.request.AccessMode,
MountOptions: pair.request.MountOptions,
}
mountInfo, err := mounter.MountVolume(ctx, pair.volume, c.alloc, usageOpts, pair.publishContext)
if err != nil {
return err
}
mounts[alias] = mountInfo
}
res := c.updater.GetAllocHookResources()
res.CSIMounts = mounts
c.updater.SetAllocHookResources(res)
return nil
}
// Postrun sends an RPC to the server to unpublish the volume. This may
// forward client RPCs to the node plugins or to the controller plugins,
// depending on whether other allocations on this node have claims on this
// volume.
func (c *csiHook) Postrun() error {
if !c.shouldRun() {
return nil
}
var wg sync.WaitGroup
errs := make(chan error, len(c.volumeRequests))
for _, pair := range c.volumeRequests {
wg.Add(1)
// CSI RPCs can potentially fail for a very long time if a
// node plugin has failed. split the work into goroutines so
// that operators could potentially reuse one of a set of
// volumes even if this hook is stuck waiting on the others
go func(pair *volumeAndRequest) {
defer wg.Done()
// we can recover an unmount failure if the operator
// brings the plugin back up, so retry every few minutes
// but eventually give up
err := c.unmountWithRetry(pair)
if err != nil {
errs <- err
return
}
// we can't recover from this RPC error client-side; the
// volume claim GC job will have to clean up for us once
// the allocation is marked terminal
errs <- c.unpublish(pair)
}(pair)
}
wg.Wait()
close(errs) // so we don't block waiting if there were no errors
var mErr *multierror.Error
for err := range errs {
mErr = multierror.Append(mErr, err)
}
return mErr.ErrorOrNil()
}
type volumeAndRequest struct {
volume *structs.CSIVolume
request *structs.VolumeRequest
// When volumeAndRequest was returned from a volume claim, this field will be
// populated for plugins that require it.
publishContext map[string]string
}
// claimVolumesFromAlloc is used by the pre-run hook to fetch all of the volume
// metadata and claim it for use by this alloc/node at the same time.
func (c *csiHook) claimVolumesFromAlloc() (map[string]*volumeAndRequest, error) {
result := make(map[string]*volumeAndRequest)
tg := c.alloc.Job.LookupTaskGroup(c.alloc.TaskGroup)
// Initially, populate the result map with all of the requests
for alias, volumeRequest := range tg.Volumes {
if volumeRequest.Type == structs.VolumeTypeCSI {
for _, task := range tg.Tasks {
caps, err := c.taskCapabilityGetter.GetTaskDriverCapabilities(task.Name)
if err != nil {
return nil, fmt.Errorf("could not validate task driver capabilities: %v", err)
}
if caps.MountConfigs == drivers.MountConfigSupportNone {
return nil, fmt.Errorf(
"task driver %q for %q does not support CSI", task.Driver, task.Name)
}
}
result[alias] = &volumeAndRequest{request: volumeRequest}
}
}
// Iterate over the result map and upsert the volume field as each volume gets
// claimed by the server.
for alias, pair := range result {
claimType := structs.CSIVolumeClaimWrite
if pair.request.ReadOnly {
claimType = structs.CSIVolumeClaimRead
}
source := pair.request.Source
if pair.request.PerAlloc {
source = source + structs.AllocSuffix(c.alloc.Name)
}
req := &structs.CSIVolumeClaimRequest{
VolumeID: source,
AllocationID: c.alloc.ID,
NodeID: c.alloc.NodeID,
Claim: claimType,
AccessMode: pair.request.AccessMode,
AttachmentMode: pair.request.AttachmentMode,
WriteRequest: structs.WriteRequest{
Region: c.alloc.Job.Region,
Namespace: c.alloc.Job.Namespace,
AuthToken: c.nodeSecret,
},
}
var resp structs.CSIVolumeClaimResponse
if err := c.rpcClient.RPC("CSIVolume.Claim", req, &resp); err != nil {
return nil, fmt.Errorf("could not claim volume %s: %w", req.VolumeID, err)
}
if resp.Volume == nil {
return nil, fmt.Errorf("Unexpected nil volume returned for ID: %v", pair.request.Source)
}
result[alias].request = pair.request
result[alias].volume = resp.Volume
result[alias].publishContext = resp.PublishContext
}
return result, nil
}
func (c *csiHook) shouldRun() bool {
tg := c.alloc.Job.LookupTaskGroup(c.alloc.TaskGroup)
for _, vol := range tg.Volumes {
if vol.Type == structs.VolumeTypeCSI {
return true
}
}
return false
}
func (c *csiHook) unpublish(pair *volumeAndRequest) error {
mode := structs.CSIVolumeClaimRead
if !pair.request.ReadOnly {
mode = structs.CSIVolumeClaimWrite
}
source := pair.request.Source
if pair.request.PerAlloc {
// NOTE: PerAlloc can't be set if we have canaries
source = source + structs.AllocSuffix(c.alloc.Name)
}
req := &structs.CSIVolumeUnpublishRequest{
VolumeID: source,
Claim: &structs.CSIVolumeClaim{
AllocationID: c.alloc.ID,
NodeID: c.alloc.NodeID,
Mode: mode,
State: structs.CSIVolumeClaimStateUnpublishing,
},
WriteRequest: structs.WriteRequest{
Region: c.alloc.Job.Region,
Namespace: c.alloc.Job.Namespace,
AuthToken: c.nodeSecret,
},
}
return c.rpcClient.RPC("CSIVolume.Unpublish",
req, &structs.CSIVolumeUnpublishResponse{})
}
// unmountWithRetry tries to unmount/unstage the volume, retrying with
// exponential backoff capped to a maximum interval
func (c *csiHook) unmountWithRetry(pair *volumeAndRequest) error {
// note: allocrunner hooks don't have access to the client's
// shutdown context, just the allocrunner's shutdown; if we make
// it available in the future we should thread it through here so
// that retry can exit gracefully instead of dropping the
// in-flight goroutine
ctx, cancel := context.WithTimeout(context.TODO(), c.maxBackoffDuration)
defer cancel()
var err error
backoff := time.Second
t, stop := helper.NewSafeTimer(0)
defer stop()
for {
select {
case <-ctx.Done():
return err
case <-t.C:
}
err = c.unmountImpl(pair)
if err == nil {
break
}
if backoff < c.maxBackoffInterval {
backoff = backoff * 2
if backoff > c.maxBackoffInterval {
backoff = c.maxBackoffInterval
}
}
t.Reset(backoff)
}
return nil
}
// unmountImpl implements the call to the CSI plugin manager to
// unmount the volume. Each retry will write an "Unmount volume"
// NodeEvent
func (c *csiHook) unmountImpl(pair *volumeAndRequest) error {
mounter, err := c.csimanager.MounterForPlugin(context.TODO(), pair.volume.PluginID)
if err != nil {
return err
}
usageOpts := &csimanager.UsageOptions{
ReadOnly: pair.request.ReadOnly,
AttachmentMode: pair.request.AttachmentMode,
AccessMode: pair.request.AccessMode,
MountOptions: pair.request.MountOptions,
}
return mounter.UnmountVolume(context.TODO(),
pair.volume.ID, pair.volume.RemoteID(), c.alloc.ID, usageOpts)
}