support the provisioner_engine metadata value (#135)

## Description

Boots should check the provisioiner_engine metadata value against the PROVISIONER_ENGINE_NAME runtime environment to decide if it should be handling DHCP requests for a given piece of hardware.

## Why is this needed

To allow for multiple differing versions of boots to be running in an environment, with DHCP relayed to both simultaneously to aid in blue/green deployment testing.

job/dhcp.go

@@ -28,6 +28,12 @@ func IsSpecialOS(i *packet.Instance) bool {
 // ServeDHCP responds to DHCP packets
 func (j Job) ServeDHCP(w dhcp4.ReplyWriter, req *dhcp4.Packet) bool {
 
+	// If we are not the chosen provisioner for this piece of hardware
+	// do not respond to the DHCP request
+	if !j.areWeProvisioner() {
+		return false
+	}
+
 	// setup reply
 	reply := dhcp.NewReply(w, req)
 	if reply == nil {
@@ -83,6 +89,14 @@ func (j Job) isPXEAllowed() bool {
 	return j.instance.AllowPXE
 }
 
+func (j Job) areWeProvisioner() bool {
+	if j.hardware.HardwareProvisioner() == "" {
+		return true
+	}
+
+	return j.hardware.HardwareProvisioner() == j.ProvisionerEngineName()
+}
+
 func (j Job) setPXEFilename(rep *dhcp4.Packet, isPacket, isARM, isUEFI bool) {
 	if j.HardwareState() == "in_use" {
 		if j.InstanceID() == "" {

job/dhcp_test.go

@@ -117,6 +117,34 @@ func TestAllowPXE(t *testing.T) {
 	}
 }
 
+func TestAreWeProvisioner(t *testing.T) {
+	for _, tt := range []struct {
+		want              bool
+		ProvisionerEngine string
+		env               string
+	}{
+		{want: true, ProvisionerEngine: "tinkerbell", env: "tinkerbell"},
+		{want: false, ProvisionerEngine: "tinkerbell", env: "packet"},
+		{want: true, ProvisionerEngine: "", env: "packet"},
+		{want: false, ProvisionerEngine: "tinkerbell", env: ""},
+	} {
+		t.Logf("want=%t, ProvisionerEngine=%s env=%s",
+			tt.want, tt.ProvisionerEngine, tt.env)
+		j := Job{
+			hardware: &packet.HardwareTinkerbellV1{
+				Metadata: packet.Metadata{
+					ProvisionerEngine: tt.ProvisionerEngine,
+				},
+			},
+		}
+		SetProvisionerEngineName(tt.env)
+		got := j.areWeProvisioner()
+		if got != tt.want {
+			t.Fatalf("unexpected return, want: %t, got %t", tt.want, got)
+		}
+	}
+}
+
 func TestIsSpecialOS(t *testing.T) {
 	t.Run("nil instance", func(t *testing.T) {
 		special := IsSpecialOS(nil)

job/job.go

@@ -14,12 +14,19 @@ import (
 )
 
 var client *packet.Client
+var provisionerEngineName string
 
 // SetClient sets the client used to interact with the api.
 func SetClient(c *packet.Client) {
 	client = c
 }
 
+// SetProvisionerEngineName sets the provisioning engine name used
+// for this instance of boots
+func SetProvisionerEngineName(engineName string) {
+	provisionerEngineName = engineName
+}
+
 // Job this comment is useless
 type Job struct {
 	log.Logger
@@ -42,6 +49,12 @@ func (j Job) AllowPxe() bool {
 	return j.hardware.HardwareAllowPXE(j.mac)
 }
 
+// ProvisionerEngineName returns the current provisioning engine name
+// as defined by the env var PROVISIONER_ENGINE_NAME supplied at runtime
+func (j Job) ProvisionerEngineName() string {
+	return provisionerEngineName
+}
+
 // HasActiveWorkflow fetches workflows for the given hardware and returns
 // the status true if there is a pending (active) workflow
 func HasActiveWorkflow(hwID packet.HardwareID) (bool, error) {

main.go

@@ -28,8 +28,9 @@ import (
 )
 
 var (
-	client     *packet.Client
-	apiBaseURL = env.URL("API_BASE_URL", "https://api.packet.net")
+	client                *packet.Client
+	apiBaseURL            = env.URL("API_BASE_URL", "https://api.packet.net")
+	provisionerEngineName = env.Get("PROVISIONER_ENGINE_NAME", "packet")
 
 	mainlog log.Logger
 
@@ -73,6 +74,7 @@ func main() {
 		mainlog.Fatal(err)
 	}
 	job.SetClient(client)
+	job.SetProvisionerEngineName(provisionerEngineName)
 
 	go func() {
 		mainlog.Info("serving syslog")

packet/models.go

@@ -62,6 +62,7 @@ type Hardware interface {
 	HardwareIPs() []IP
 	Interfaces() []Port // TODO: to be updated
 	HardwareManufacturer() string
+	HardwareProvisioner() string
 	HardwarePlanSlug() string
 	HardwarePlanVersionSlug() string
 	HardwareState() HardwareState
@@ -296,7 +297,8 @@ type Metadata struct {
 		PreinstalledOS OperatingSystem `json:"preinstalled_operating_system_version"`
 		PrivateSubnets []string        `json:"private_subnets"`
 	} `json:"custom"`
-	Facility Facility `json:"facility"`
+	Facility          Facility `json:"facility"`
+	ProvisionerEngine string   `json:"provisioner_engine"`
 }
 
 // Facility represents the facilty in use

packet/models_cacher.go

@@ -22,22 +22,23 @@ type HardwareCacher struct {
 	Name  string        `json:"name"`
 	State HardwareState `json:"state"`
 
-	BondingMode     BondingMode     `json:"bonding_mode"`
-	NetworkPorts    []Port          `json:"network_ports"`
-	Manufacturer    Manufacturer    `json:"manufacturer"`
-	PlanSlug        string          `json:"plan_slug"`
-	PlanVersionSlug string          `json:"plan_version_slug"`
-	Arch            string          `json:"arch"`
-	FacilityCode    string          `json:"facility_code"`
-	IPMI            IP              `json:"management"`
-	IPs             []IP            `json:"ip_addresses"`
-	PreinstallOS    OperatingSystem `json:"preinstalled_operating_system_version"`
-	PrivateSubnets  []string        `json:"private_subnets,omitempty"`
-	UEFI            bool            `json:"efi_boot"`
-	AllowPXE        bool            `json:"allow_pxe"`
-	AllowWorkflow   bool            `json:"allow_workflow"`
-	ServicesVersion ServicesVersion `json:"services"`
-	Instance        *Instance       `json:"instance"`
+	BondingMode       BondingMode     `json:"bonding_mode"`
+	NetworkPorts      []Port          `json:"network_ports"`
+	Manufacturer      Manufacturer    `json:"manufacturer"`
+	PlanSlug          string          `json:"plan_slug"`
+	PlanVersionSlug   string          `json:"plan_version_slug"`
+	Arch              string          `json:"arch"`
+	FacilityCode      string          `json:"facility_code"`
+	IPMI              IP              `json:"management"`
+	IPs               []IP            `json:"ip_addresses"`
+	PreinstallOS      OperatingSystem `json:"preinstalled_operating_system_version"`
+	PrivateSubnets    []string        `json:"private_subnets,omitempty"`
+	UEFI              bool            `json:"efi_boot"`
+	AllowPXE          bool            `json:"allow_pxe"`
+	AllowWorkflow     bool            `json:"allow_workflow"`
+	ServicesVersion   ServicesVersion `json:"services"`
+	Instance          *Instance       `json:"instance"`
+	ProvisionerEngine string          `json:"provisioner_engine"`
 }
 
 func (d DiscoveryCacher) Hardware() Hardware {
@@ -308,6 +309,10 @@ func (h HardwareCacher) HardwareManufacturer() string {
 	return h.Manufacturer.Slug
 }
 
+func (h HardwareCacher) HardwareProvisioner() string {
+	return h.ProvisionerEngine
+}
+
 func (h HardwareCacher) HardwarePlanSlug() string {
 	return h.PlanSlug
 }

packet/models_tinkerbell.go

@@ -146,6 +146,10 @@ func (h HardwareTinkerbellV1) HardwareIPs() []IP {
 //	return h.DHCP.IP // is this correct?
 //}
 
+func (h HardwareTinkerbellV1) HardwareProvisioner() string {
+	return h.Metadata.ProvisionerEngine
+}
+
 func (h HardwareTinkerbellV1) HardwareManufacturer() string {
 	return h.Metadata.Manufacturer.Slug
 }