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device.go
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device.go
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package example
import (
"context"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sync"
"time"
log "github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/helper"
"github.com/hashicorp/nomad/plugins/base"
"github.com/hashicorp/nomad/plugins/device"
"github.com/hashicorp/nomad/plugins/shared/hclspec"
"github.com/hashicorp/nomad/plugins/shared/structs"
"github.com/kr/pretty"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
)
const (
// pluginName is the name of the plugin
pluginName = "example-fs-device"
// vendor is the vendor providing the devices
vendor = "nomad"
// deviceType is the type of device being returned
deviceType = "file"
// deviceName is the name of the devices being exposed
deviceName = "mock"
)
var (
// pluginInfo describes the plugin
pluginInfo = &base.PluginInfoResponse{
Type: base.PluginTypeDevice,
PluginApiVersions: []string{device.ApiVersion010},
PluginVersion: "v0.1.0",
Name: pluginName,
}
// configSpec is the specification of the plugin's configuration
configSpec = hclspec.NewObject(map[string]*hclspec.Spec{
"dir": hclspec.NewDefault(
hclspec.NewAttr("dir", "string", false),
hclspec.NewLiteral("\".\""),
),
"list_period": hclspec.NewDefault(
hclspec.NewAttr("list_period", "string", false),
hclspec.NewLiteral("\"5s\""),
),
"unhealthy_perm": hclspec.NewDefault(
hclspec.NewAttr("unhealthy_perm", "string", false),
hclspec.NewLiteral("\"-rwxrwxrwx\""),
),
})
)
// Config contains configuration information for the plugin.
type Config struct {
Dir string `codec:"dir"`
ListPeriod string `codec:"list_period"`
UnhealthyPerm string `codec:"unhealthy_perm"`
}
// FsDevice is an example device plugin. The device plugin exposes files as
// devices and periodically polls the directory for new files. If a file has a
// given file permission, it is considered unhealthy. This device plugin is
// purely for use as an example.
type FsDevice struct {
logger log.Logger
// deviceDir is the directory we expose as devices
deviceDir string
// unhealthyPerm is the permissions on a file we consider unhealthy
unhealthyPerm string
// listPeriod is how often we should list the device directory to detect new
// devices
listPeriod time.Duration
// devices is the set of detected devices and maps whether they are healthy
devices map[string]bool
deviceLock sync.RWMutex
}
// NewExampleDevice returns a new example device plugin.
func NewExampleDevice(log log.Logger) *FsDevice {
return &FsDevice{
logger: log.Named(pluginName),
devices: make(map[string]bool),
}
}
// PluginInfo returns information describing the plugin.
func (d *FsDevice) PluginInfo() (*base.PluginInfoResponse, error) {
return pluginInfo, nil
}
// ConfigSchema returns the plugins configuration schema.
func (d *FsDevice) ConfigSchema() (*hclspec.Spec, error) {
return configSpec, nil
}
// SetConfig is used to set the configuration of the plugin.
func (d *FsDevice) SetConfig(c *base.Config) error {
var config Config
if err := base.MsgPackDecode(c.PluginConfig, &config); err != nil {
return err
}
// Save the device directory and the unhealthy permissions
d.deviceDir = config.Dir
d.unhealthyPerm = config.UnhealthyPerm
// Convert the poll period
period, err := time.ParseDuration(config.ListPeriod)
if err != nil {
return fmt.Errorf("failed to parse list period %q: %v", config.ListPeriod, err)
}
d.listPeriod = period
d.logger.Debug("test debug")
d.logger.Info("config set", "config", log.Fmt("% #v", pretty.Formatter(config)))
return nil
}
// Fingerprint streams detected devices. If device changes are detected or the
// devices health changes, messages will be emitted.
func (d *FsDevice) Fingerprint(ctx context.Context) (<-chan *device.FingerprintResponse, error) {
if d.deviceDir == "" {
return nil, status.New(codes.Internal, "device directory not set in config").Err()
}
outCh := make(chan *device.FingerprintResponse)
go d.fingerprint(ctx, outCh)
return outCh, nil
}
// fingerprint is the long running goroutine that detects hardware
func (d *FsDevice) fingerprint(ctx context.Context, devices chan *device.FingerprintResponse) {
defer close(devices)
// Create a timer that will fire immediately for the first detection
ticker := time.NewTimer(0)
for {
select {
case <-ctx.Done():
return
case <-ticker.C:
ticker.Reset(d.listPeriod)
}
d.logger.Trace("scanning for changes")
files, err := ioutil.ReadDir(d.deviceDir)
if err != nil {
d.logger.Error("failed to list device directory", "error", err)
devices <- device.NewFingerprintError(err)
return
}
detected := d.diffFiles(files)
if len(detected) == 0 {
continue
}
devices <- device.NewFingerprint(getDeviceGroup(detected))
}
}
func (d *FsDevice) diffFiles(files []os.FileInfo) []*device.Device {
d.deviceLock.Lock()
defer d.deviceLock.Unlock()
// Build an unhealthy message
unhealthyDesc := fmt.Sprintf("Device has bad permissions %q", d.unhealthyPerm)
var changes bool
fnames := make(map[string]struct{})
for _, f := range files {
name := f.Name()
fnames[name] = struct{}{}
if f.IsDir() {
d.logger.Trace("skipping directory", "directory", name)
continue
}
// Determine the health
perms := f.Mode().Perm().String()
healthy := perms != d.unhealthyPerm
d.logger.Trace("checking health", "file perm", perms, "unhealthy perms", d.unhealthyPerm, "healthy", healthy)
// See if we alreay have the device
oldHealth, ok := d.devices[name]
if ok && oldHealth == healthy {
continue
}
// Health has changed or we have a new object
changes = true
d.devices[name] = healthy
}
for id := range d.devices {
if _, ok := fnames[id]; !ok {
delete(d.devices, id)
changes = true
}
}
// Nothing to do
if !changes {
return nil
}
// Build the devices
detected := make([]*device.Device, 0, len(d.devices))
for name, healthy := range d.devices {
var desc string
if !healthy {
desc = unhealthyDesc
}
detected = append(detected, &device.Device{
ID: name,
Healthy: healthy,
HealthDesc: desc,
})
}
return detected
}
// getDeviceGroup is a helper to build the DeviceGroup given a set of devices.
func getDeviceGroup(devices []*device.Device) *device.DeviceGroup {
return &device.DeviceGroup{
Vendor: vendor,
Type: deviceType,
Name: deviceName,
Devices: devices,
}
}
// Reserve returns information on how to mount the given devices.
func (d *FsDevice) Reserve(deviceIDs []string) (*device.ContainerReservation, error) {
if len(deviceIDs) == 0 {
return nil, status.New(codes.InvalidArgument, "no device ids given").Err()
}
deviceDir, err := filepath.Abs(d.deviceDir)
if err != nil {
return nil, status.Newf(codes.Internal, "failed to load device dir abs path").Err()
}
resp := &device.ContainerReservation{}
for _, id := range deviceIDs {
// Check if the device is known
if _, ok := d.devices[id]; !ok {
return nil, status.Newf(codes.InvalidArgument, "unknown device %q", id).Err()
}
// Add a mount
resp.Mounts = append(resp.Mounts, &device.Mount{
TaskPath: fmt.Sprintf("/tmp/task-mounts/%s", id),
HostPath: filepath.Join(deviceDir, id),
ReadOnly: false,
})
}
return resp, nil
}
// Stats streams statistics for the detected devices.
func (d *FsDevice) Stats(ctx context.Context, interval time.Duration) (<-chan *device.StatsResponse, error) {
outCh := make(chan *device.StatsResponse)
go d.stats(ctx, outCh, interval)
return outCh, nil
}
// stats is the long running goroutine that streams device statistics
func (d *FsDevice) stats(ctx context.Context, stats chan *device.StatsResponse, interval time.Duration) {
defer close(stats)
// Create a timer that will fire immediately for the first detection
ticker := time.NewTimer(0)
for {
select {
case <-ctx.Done():
return
case <-ticker.C:
ticker.Reset(interval)
}
deviceStats, err := d.collectStats()
if err != nil {
stats <- &device.StatsResponse{
Error: err,
}
return
}
if deviceStats == nil {
continue
}
stats <- &device.StatsResponse{
Groups: []*device.DeviceGroupStats{deviceStats},
}
}
}
func (d *FsDevice) collectStats() (*device.DeviceGroupStats, error) {
d.deviceLock.RLock()
defer d.deviceLock.RUnlock()
l := len(d.devices)
if l == 0 {
return nil, nil
}
now := time.Now()
group := &device.DeviceGroupStats{
Vendor: vendor,
Type: deviceType,
Name: deviceName,
InstanceStats: make(map[string]*device.DeviceStats, l),
}
for k := range d.devices {
p := filepath.Join(d.deviceDir, k)
f, err := os.Stat(p)
if err != nil {
return nil, fmt.Errorf("failed to stat %q: %v", p, err)
}
s := &device.DeviceStats{
Summary: &structs.StatValue{
IntNumeratorVal: helper.Int64ToPtr(f.Size()),
Unit: "bytes",
Desc: "Filesize in bytes",
},
Stats: &structs.StatObject{
Attributes: map[string]*structs.StatValue{
"size": {
IntNumeratorVal: helper.Int64ToPtr(f.Size()),
Unit: "bytes",
Desc: "Filesize in bytes",
},
"modify_time": {
StringVal: helper.StringToPtr(f.ModTime().String()),
Desc: "Last modified",
},
"mode": {
StringVal: helper.StringToPtr(f.Mode().String()),
Desc: "File mode",
},
},
},
Timestamp: now,
}
group.InstanceStats[k] = s
}
return group, nil
}