fleetd: support operators in metadata

Documentation/unit-files-and-scheduling.md

@@ -179,6 +179,14 @@ app.service     282f949f.../10.10.20.1  active  running
 app.service     fd1d3e94.../10.0.0.1    active  running
 ```
 
+`MachineMetadata` also support relational operators, including `<=`, `>=`, `<`, `>`, `==` and `!=`:
+
+```
+[X-Fleet]
+MachineMetadata=ram<1024
+```
+This requires an eligible machine to have the `ram` less than 1024. The value must be numeral when using `<=`, `>=`, `<` or `>`.
+
 A machine is not automatically configured with metadata.
 A deployer may define machine metadata using the `metadata` [config option][config-option].
 

fleetctl/list_machines.go

@@ -123,7 +123,11 @@ func formatMetadata(metadata map[string]string) string {
 	sorted.Sort()
 	for _, key := range sorted {
 		value := metadata[key]
-		pairs[idx] = fmt.Sprintf("%s=%s", key, value)
+		if hasMetadataOperator(value) {
+			pairs[idx] = fmt.Sprintf("%s%s", key, value)
+		} else {
+			pairs[idx] = fmt.Sprintf("%s=%s", key, value)
+		}
 		idx++
 	}
 	return strings.Join(pairs, ",")
@@ -135,3 +139,12 @@ func machineToFieldKeys(m map[string]machineToField) (keys []string) {
 	}
 	return
 }
+
+func hasMetadataOperator(instr string) bool {
+	for _, op := range []string{"<=", ">=", "!=", "==", "<", ">"} {
+		if strings.HasPrefix(instr, op) {
+			return true
+		}
+	}
+	return false
+}

functional/fixtures/units/metadata-op.service

@@ -0,0 +1,5 @@
+[Service]
+ExecStart=/bin/bash -c "while true; do echo Hello, World!; sleep 1; done"
+
+[X-Fleet]
+MachineMetadata="ram>=1024"

functional/metadata_test.go

@@ -16,6 +16,7 @@ package functional
 
 import (
 	"fmt"
+	"path"
 	"regexp"
 	"strings"
 	"testing"
@@ -90,3 +91,87 @@ func TestTemplatesWithSpecifiersInMetadata(t *testing.T) {
 		t.Fatalf("metadata@invalid unit should not be scheduled: \nstdout: %s\nstderr: %s", stdout, stderr)
 	}
 }
+
+// TestMetadataOperator ensures that metadata operators work also for
+// extended operators such as ">=", "<=", "<", ">", "!=", or "==".
+func TestMetadataOperator(t *testing.T) {
+	cluster, err := platform.NewNspawnCluster("smoke")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cluster.Destroy(t)
+
+	members, err := platform.CreateNClusterMembers(cluster, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	m0 := members[0]
+	_, err = cluster.WaitForNMachines(m0, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stdout, stderr, err := cluster.Fleetctl(m0, "list-machines", "--fields", "machine,metadata")
+	if err != nil {
+		t.Fatalf("Unable to get machine metadata\nstdout: %s\nstderr: %s\nerr: %v", stdout, stderr, err)
+	}
+
+	runMetaOp := func(ramEq string, expectSuccess bool) {
+		tmpMdOpService := "/tmp/metadata-op.service"
+		MdOpService := "fixtures/units/metadata-op.service"
+		MdOpBaseName := path.Base(MdOpService)
+		var nUnits int
+
+		if expectSuccess {
+			t.Logf("Testing %s expecting success...", ramEq)
+			nUnits = 1
+		} else {
+			t.Logf("Testing %s expecting failure...", ramEq)
+			nUnits = 0
+		}
+
+		err = util.GenNewFleetService(tmpMdOpService, MdOpService, ramEq, "ram>=1024")
+		if err != nil {
+			t.Fatalf("Failed to generate a temp fleet service: %v", err)
+		}
+
+		stdout, stderr, err = cluster.Fleetctl(m0, "start", "--no-block", tmpMdOpService)
+		if err != nil {
+			t.Fatalf("starting unit %s returned error:\nstdout: %s\nstderr: %s\nerr: %v",
+				tmpMdOpService, stdout, stderr, err)
+		}
+
+		_, err = cluster.WaitForNActiveUnits(m0, nUnits)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		stdout, stderr, err = cluster.Fleetctl(m0, "destroy", MdOpBaseName)
+		if err != nil {
+			t.Fatalf("unit %s cannot be stopped: \nstdout: %s\nstderr: %s\nerr: %v",
+				MdOpBaseName, stdout, stderr, err)
+		}
+
+		_, err = cluster.WaitForNUnitFiles(m0, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+	}
+
+	// run tests for success cases
+	runMetaOp("ram>=1024", true)
+	runMetaOp("ram<=1024", true)
+	runMetaOp("ram>1023", true)
+	runMetaOp("ram<1025", true)
+	runMetaOp("ram!=1025", true)
+	runMetaOp("ram==1024", true)
+
+	// run tests for failure cases
+	runMetaOp("ram>=1025", false)
+	runMetaOp("ram<=1023", false)
+	runMetaOp("ram>1024", false)
+	runMetaOp("ram<1024", false)
+	runMetaOp("ram!=1024", false)
+	runMetaOp("ram==1025", false)
+}

functional/util/config.go

@@ -26,6 +26,7 @@ import (
 
 const (
 	fleetAPIPort = 54728
+	fleetRAM     = 1024 // in MiB
 	FleetTTL     = "3s"
 	cloudConfig  = `#cloud-config
 
@@ -62,7 +63,7 @@ coreos:
     command: start
     content: |
      [Service]
-     Environment=FLEET_METADATA=hostname=%H
+     Environment=FLEET_METADATA=hostname=%H,ram={{printf "%d" .FleetRAM}}
      ExecStart=/opt/fleet/fleetd -config /opt/fleet/fleet.conf
 `
 )
@@ -80,6 +81,7 @@ type configValues struct {
 	EtcdEndpoint  string
 	EtcdKeyPrefix string
 	FleetAPIPort  int
+	FleetRAM      int
 	FleetAgentTTL string
 	FleetExtra    string
 }
@@ -118,6 +120,7 @@ func BuildCloudConfig(dst io.Writer, ip, etcdEndpoint, etcdKeyPrefix string) err
 		EtcdEndpoint:  etcdEndpoint,
 		EtcdKeyPrefix: etcdKeyPrefix,
 		FleetAPIPort:  fleetAPIPort,
+		FleetRAM:      fleetRAM,
 		FleetAgentTTL: FleetTTL,
 		FleetExtra:    os.Getenv("FLEETD_TEST_ENV"),
 	}

job/job.go

@@ -284,7 +284,17 @@ func (j *Job) RequiredTargetMetadata() map[string]pkg.Set {
 		fleetMachineMetadata,
 	} {
 		for _, valuePair := range j.requirements()[key] {
-			s := strings.Split(valuePair, "=")
+			var s []string
+			for _, sep := range []string{"==", "<=", ">=", "!=", "<", ">"} {
+				index := strings.Index(valuePair, sep)
+				if index != -1 {
+					s = []string{valuePair[0:index], valuePair[index:]}
+					break
+				}
+			}
+			if s == nil {
+				s = strings.Split(valuePair, "=")
+			}
 
 			if len(s) != 2 {
 				continue

machine/machine.go

@@ -15,6 +15,9 @@
 package machine
 
 import (
+	"strconv"
+	"strings"
+
 	"github.com/coreos/fleet/log"
 	"github.com/coreos/fleet/pkg"
 )
@@ -38,8 +41,89 @@ func HasMetadata(state *MachineState, metadata map[string]pkg.Set) bool {
 		if values.Contains(local) {
 			log.Debugf("Local Metadata(%s) meets requirement", key)
 		} else {
-			log.Debugf("Local Metadata(%s) does not match requirement", key)
-			return false
+			vs := values.Values()
+			for _, v := range vs {
+				if index := strings.Index(v, "<="); strings.Contains(v, "<=") && (index == 0) {
+					need, err1 := strconv.Atoi(v[2:])
+					have, err2 := strconv.Atoi(local)
+					if err1 == nil && err2 == nil {
+						if have <= need {
+							log.Debugf("Local Metadata(%s) meets requirement", key)
+							continue
+						} else {
+							log.Debugf("Local Metadata(%s) does not match requirement", key)
+							return false
+						}
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else if index := strings.Index(v, ">="); strings.Contains(v, ">=") && (index == 0) {
+					need, err1 := strconv.Atoi(v[2:])
+					have, err2 := strconv.Atoi(local)
+					if err1 == nil && err2 == nil {
+						if have >= need {
+							log.Debugf("Local Metadata(%s) meets requirement", key)
+							continue
+						} else {
+							log.Debugf("Local Metadata(%s) does not match requirement", key)
+							return false
+						}
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else if index := strings.Index(v, ">"); strings.Contains(v, ">") && (index == 0) {
+					need, err1 := strconv.Atoi(v[1:])
+					have, err2 := strconv.Atoi(local)
+					if err1 == nil && err2 == nil {
+						if have > need {
+							log.Debugf("Local Metadata(%s) meets requirement", key)
+							continue
+						} else {
+							log.Debugf("Local Metadata(%s) does not match requirement", key)
+							return false
+						}
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else if index := strings.Index(v, "<"); strings.Contains(v, "<") && (index == 0) {
+					need, err1 := strconv.Atoi(v[1:])
+					have, err2 := strconv.Atoi(local)
+					if err1 == nil && err2 == nil {
+						if have < need {
+							log.Debugf("Local Metadata(%s) meets requirement", key)
+							continue
+						} else {
+							log.Debugf("Local Metadata(%s) does not match requirement", key)
+							return false
+						}
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else if index := strings.Index(v, "!="); strings.Contains(v, "!=") && (index == 0) {
+					if v[2:] != local {
+						log.Debugf("Local Metadata(%s) meets requirement", key)
+						continue
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else if index := strings.Index(v, "=="); strings.Contains(v, "==") && (index == 0) {
+					if v[2:] == local {
+						log.Debugf("Local Metadata(%s) meets requirement", key)
+						continue
+					} else {
+						log.Debugf("Local Metadata(%s) does not match requirement", key)
+						return false
+					}
+				} else {
+					log.Debugf("Local Metadata(%s) does not match requirement", key)
+					return false
+				}
+			}
 		}
 	}