89 lines
2.4 KiB
Go
89 lines
2.4 KiB
Go
package fingerprint
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import (
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"fmt"
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"log"
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"time"
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client "github.com/hashicorp/nomad/client/config"
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"github.com/hashicorp/nomad/nomad/structs"
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)
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const (
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cgroupAvailable = "available"
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cgroupUnavailable = "unavailable"
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interval = 15
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)
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type CGroupFingerprint struct {
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logger *log.Logger
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lastState string
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mountPointDetector MountPointDetector
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}
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// An interface to isolate calls to the cgroup library
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// This facilitates testing where we can implement
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// fake mount points to test various code paths
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type MountPointDetector interface {
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MountPoint() (string, error)
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}
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// Implements the interface detector which calls the cgroups library directly
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type DefaultMountPointDetector struct {
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}
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// Call out to the default cgroup library
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func (b *DefaultMountPointDetector) MountPoint() (string, error) {
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return FindCgroupMountpointDir()
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}
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// NewCGroupFingerprint returns a new cgroup fingerprinter
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func NewCGroupFingerprint(logger *log.Logger) Fingerprint {
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f := &CGroupFingerprint{
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logger: logger,
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lastState: cgroupUnavailable,
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mountPointDetector: &DefaultMountPointDetector{},
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}
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return f
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}
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// Fingerprint tries to find a valid cgroup moint point
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func (f *CGroupFingerprint) Fingerprint(cfg *client.Config, node *structs.Node) (bool, error) {
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mount, err := f.mountPointDetector.MountPoint()
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if err != nil {
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f.clearCGroupAttributes(node)
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return false, fmt.Errorf("Failed to discover cgroup mount point: %s", err)
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}
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// Check if a cgroup mount point was found
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if mount == "" {
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// Clear any attributes from the previous fingerprint.
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f.clearCGroupAttributes(node)
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if f.lastState == cgroupAvailable {
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f.logger.Printf("[INFO] fingerprint.cgroups: cgroups are unavailable")
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}
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f.lastState = cgroupUnavailable
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return true, nil
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}
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node.Attributes["unique.cgroup.mountpoint"] = mount
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if f.lastState == cgroupUnavailable {
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f.logger.Printf("[INFO] fingerprint.cgroups: cgroups are available")
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}
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f.lastState = cgroupAvailable
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return true, nil
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}
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// clearCGroupAttributes clears any node attributes related to cgroups that might
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// have been set in a previous fingerprint run.
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func (f *CGroupFingerprint) clearCGroupAttributes(n *structs.Node) {
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delete(n.Attributes, "unique.cgroup.mountpoint")
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}
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// Periodic determines the interval at which the periodic fingerprinter will run.
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func (f *CGroupFingerprint) Periodic() (bool, time.Duration) {
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return true, interval * time.Second
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}
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