Merge pull request #9720 from hashicorp/b-consul-sreg-update

consul: always include task services hook

CHANGELOG.md

@@ -5,6 +5,7 @@ IMPROVEMENTS:
  * consul/connect: interpolate the connect, service meta, and service canary meta blocks with the task environment [[GH-9586](https://github.com/hashicorp/nomad/pull/9586)]
 
 BUG FIXES:
+ * consul: Fixed a bug where updating a task to include services would not work [[GH-9707](https://github.com/hashicorp/nomad/issues/9707)]
  * template: Fixed multiple issues in template src/dest and artifact dest interpolation [[GH-9671](https://github.com/hashicorp/nomad/issues/9671)]
  * template: Fixed a bug where dynamic secrets did not trigger the template `change_mode` after a client restart. [[GH-9636](https://github.com/hashicorp/nomad/issues/9636)]
  * server: Fixed a bug where new servers may bootstrap prematurely when configured with `bootstrap_expect = 0`.

client/allocrunner/taskrunner/task_runner_hooks.go

@@ -101,8 +101,8 @@ func (tr *TaskRunner) initHooks() {
 		}))
 	}
 
-	// If there are any services, add the service hook
+	// Always add the service hook. A task with no services on initial registration
-	if len(task.Services) != 0 {
+	// may be updated to include services, which must be handled with this hook.
 	tr.runnerHooks = append(tr.runnerHooks, newServiceHook(serviceHookConfig{
 		alloc:     tr.Alloc(),
 		task:      tr.Task(),
@@ -110,7 +110,6 @@ func (tr *TaskRunner) initHooks() {
 		restarter: tr,
 		logger:    hookLogger,
 	}))
-	}
 
 	// If this is a Connect sidecar proxy (or a Connect Native) service,
 	// add the sidsHook for requesting a Service Identity token (if ACLs).

e2e/consul/consul.go

@@ -17,6 +17,9 @@ import (
 const (
 	consulJobBasic      = "consul/input/consul_example.nomad"
 	consulJobCanaryTags = "consul/input/canary_tags.nomad"
+
+	consulJobRegisterOnUpdatePart1 = "consul/input/services_empty.nomad"
+	consulJobRegisterOnUpdatePart2 = "consul/input/services_present.nomad"
 )
 
 type ConsulE2ETest struct {
@@ -47,24 +50,25 @@ func (tc *ConsulE2ETest) AfterEach(f *framework.F) {
 	}
 
 	for _, id := range tc.jobIds {
-		tc.Nomad().Jobs().Deregister(id, true, nil)
+		_, _, err := tc.Nomad().Jobs().Deregister(id, true, nil)
+		require.NoError(f.T(), err)
 	}
 	tc.jobIds = []string{}
-	tc.Nomad().System().GarbageCollect()
+	require.NoError(f.T(), tc.Nomad().System().GarbageCollect())
 }
 
 // TestConsulRegistration asserts that a job registers services with tags in Consul.
 func (tc *ConsulE2ETest) TestConsulRegistration(f *framework.F) {
 	t := f.T()
+	r := require.New(t)
 
 	nomadClient := tc.Nomad()
-	catalog := tc.Consul().Catalog()
+	jobId := "consul" + uuid.Short()
-	jobId := "consul" + uuid.Generate()[0:8]
 	tc.jobIds = append(tc.jobIds, jobId)
 
-	allocs := e2eutil.RegisterAndWaitForAllocs(f.T(), nomadClient, consulJobBasic, jobId, "")
+	allocations := e2eutil.RegisterAndWaitForAllocs(f.T(), nomadClient, consulJobBasic, jobId, "")
-	require.Equal(t, 3, len(allocs))
+	require.Equal(t, 3, len(allocations))
-	allocIDs := e2eutil.AllocIDsFromAllocationListStubs(allocs)
+	allocIDs := e2eutil.AllocIDsFromAllocationListStubs(allocations)
 	e2eutil.WaitForAllocsRunning(t, tc.Nomad(), allocIDs)
 
 	expectedTags := []string{
@@ -73,42 +77,58 @@ func (tc *ConsulE2ETest) TestConsulRegistration(f *framework.F) {
 	}
 
 	// Assert services get registered
-	testutil.WaitForResult(func() (bool, error) {
+	e2eutil.RequireConsulRegistered(r, tc.Consul(), "consul-example", 3)
-		services, _, err := catalog.Service("consul-example", "", nil)
+	services, _, err := tc.Consul().Catalog().Service("consul-example", "", nil)
-		if err != nil {
+	require.NoError(t, err)
-			return false, fmt.Errorf("error contacting Consul: %v", err)
-		}
-		if expected := 3; len(services) != expected {
-			return false, fmt.Errorf("expected %d services but found %d", expected, len(services))
-		}
 	for _, s := range services {
 		// If we've made it this far the tags should *always* match
-			require.True(t, helper.CompareSliceSetString(expectedTags, s.ServiceTags))
+		require.ElementsMatch(t, expectedTags, s.ServiceTags)
 	}
-		return true, nil
-	}, func(err error) {
-		t.Fatalf("error waiting for services to be registered: %v", err)
-	})
 
 	// Stop the job
 	e2eutil.WaitForJobStopped(t, nomadClient, jobId)
 
-	// Verify that services were deregistered in Consul
+	// Verify that services were de-registered in Consul
-	testutil.WaitForResult(func() (bool, error) {
+	e2eutil.RequireConsulDeregistered(r, tc.Consul(), "consul-example")
-		s, _, err := catalog.Service("consul-example", "", nil)
+}
-		if err != nil {
-			return false, err
-		}
 
-		return len(s) == 0, fmt.Errorf("expected 0 services but found: %v", s)
+func (tc *ConsulE2ETest) TestConsulRegisterOnUpdate(f *framework.F) {
-	}, func(err error) {
+	t := f.T()
-		t.Fatalf("error waiting for services to be deregistered: %v", err)
+	r := require.New(t)
-	})
+
+	nomadClient := tc.Nomad()
+	catalog := tc.Consul().Catalog()
+	jobID := "consul" + uuid.Short()
+	tc.jobIds = append(tc.jobIds, jobID)
+
+	// Initial job has no services for task.
+	allocations := e2eutil.RegisterAndWaitForAllocs(t, nomadClient, consulJobRegisterOnUpdatePart1, jobID, "")
+	require.Equal(t, 1, len(allocations))
+	allocIDs := e2eutil.AllocIDsFromAllocationListStubs(allocations)
+	e2eutil.WaitForAllocsRunning(t, tc.Nomad(), allocIDs)
+
+	// Assert service not yet registered.
+	results, _, err := catalog.Service("nc-service", "", nil)
+	require.NoError(t, err)
+	require.Empty(t, results)
+
+	// On update, add services for task.
+	allocations = e2eutil.RegisterAndWaitForAllocs(t, nomadClient, consulJobRegisterOnUpdatePart2, jobID, "")
+	require.Equal(t, 1, len(allocations))
+	allocIDs = e2eutil.AllocIDsFromAllocationListStubs(allocations)
+	e2eutil.WaitForAllocsRunning(t, tc.Nomad(), allocIDs)
+
+	// Assert service is now registered.
+	e2eutil.RequireConsulRegistered(r, tc.Consul(), "nc-service", 1)
 }
 
 // TestCanaryInplaceUpgrades verifies setting and unsetting canary tags
 func (tc *ConsulE2ETest) TestCanaryInplaceUpgrades(f *framework.F) {
 	t := f.T()
+
+	// TODO(shoenig) https://github.com/hashicorp/nomad/issues/9627
+	t.Skip("THIS TEST IS BROKEN (#9627)")
+
 	nomadClient := tc.Nomad()
 	consulClient := tc.Consul()
 	jobId := "consul" + uuid.Generate()[0:8]

e2e/consul/input/consul_example.nomad

@@ -23,7 +23,7 @@ job "consul-example" {
     healthy_deadline = "5m"
   }
 
-  group "cache" {
+  group "group" {
     count = 3
 
     network {
@@ -41,7 +41,7 @@ job "consul-example" {
       size = 300
     }
 
-    task "redis" {
+    task "example" {
       driver = "docker"
 
       config {

e2e/consul/input/services_empty.nomad

@@ -0,0 +1,29 @@
+job "consul-register-on-update" {
+  datacenters = ["dc1"]
+  type        = "service"
+
+  constraint {
+    attribute = "${attr.kernel.name}"
+    value     = "linux"
+  }
+
+  group "echo" {
+
+    task "busybox-nc" {
+      driver = "docker"
+
+      config {
+        image   = "busybox:1"
+        command = "nc"
+        args = [
+          "-ll",
+          "-p",
+          "1234",
+          "-e",
+        "/bin/cat"]
+      }
+
+      # no initial service definition
+    }
+  }
+}

e2e/consul/input/services_present.nomad

@@ -0,0 +1,31 @@
+job "consul-register-on-update" {
+  datacenters = ["dc1"]
+  type        = "service"
+
+  constraint {
+    attribute = "${attr.kernel.name}"
+    value     = "linux"
+  }
+
+  group "echo" {
+
+    task "busybox-nc" {
+      driver = "docker"
+
+      config {
+        image   = "busybox:1"
+        command = "nc"
+        args = [
+          "-ll",
+          "-p",
+          "1234",
+          "-e",
+        "/bin/cat"]
+      }
+
+      service {
+        name = "nc-service"
+      }
+    }
+  }
+}

e2e/consul/script_checks.go

@@ -32,64 +32,65 @@ func (tc *ScriptChecksE2ETest) BeforeAll(f *framework.F) {
 // and associated script checks. It updates, stops, etc. the job to verify
 // that script checks are re-registered as expected.
 func (tc *ScriptChecksE2ETest) TestGroupScriptCheck(f *framework.F) {
+	r := require.New(f.T())
+
 	nomadClient := tc.Nomad()
-	uuid := uuid.Generate()
-	require := require.New(f.T())
 	consulClient := tc.Consul()
 
-	jobId := "checks_group" + uuid[0:8]
+	jobId := "checks_group" + uuid.Short()
 	tc.jobIds = append(tc.jobIds, jobId)
 
 	// Job run: verify that checks were registered in Consul
 	allocs := e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_group.nomad", jobId, "")
-	require.Equal(1, len(allocs))
+	r.Equal(1, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-3", capi.HealthCritical)
 
 	// Check in warning state becomes healthy after check passes
 	_, _, err := exec(nomadClient, allocs,
 		[]string{"/bin/sh", "-c", "touch /tmp/${NOMAD_ALLOC_ID}-alive-2b"})
-	require.NoError(err)
+	r.NoError(err)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-2", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-2", capi.HealthPassing)
 
 	// Job update: verify checks are re-registered in Consul
 	allocs = e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_group_update.nomad", jobId, "")
-	require.Equal(1, len(allocs))
+	r.Equal(1, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-2", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-2", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-3", capi.HealthCritical)
 
 	// Verify we don't have any linger script checks running on the client
 	out, _, err := exec(nomadClient, allocs, []string{"pgrep", "sleep"})
-	require.NoError(err)
+	r.NoError(err)
 	running := strings.Split(strings.TrimSpace(out.String()), "\n")
-	require.LessOrEqual(len(running), 2) // task itself + 1 check == 2
+	r.LessOrEqual(len(running), 2) // task itself + 1 check == 2
 
 	// Clean job stop: verify that checks were deregistered in Consul
-	nomadClient.Jobs().Deregister(jobId, false, nil) // nomad job stop
+	_, _, err = nomadClient.Jobs().Deregister(jobId, false, nil) // nomad job stop
-	e2eutil.RequireConsulDeregistered(require, consulClient, "group-service-1")
+	r.NoError(err)
-	e2eutil.RequireConsulDeregistered(require, consulClient, "group-service-2")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "group-service-1")
-	e2eutil.RequireConsulDeregistered(require, consulClient, "group-service-3")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "group-service-2")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "group-service-3")
 
 	// Restore for next test
 	allocs = e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_group.nomad", jobId, "")
-	require.Equal(2, len(allocs))
+	r.Equal(2, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-3", capi.HealthCritical)
 
 	// Crash a task: verify that checks become healthy again
 	_, _, err = exec(nomadClient, allocs, []string{"pkill", "sleep"})
 	if err != nil && err.Error() != "plugin is shut down" {
-		require.FailNow("unexpected error: %v", err)
+		r.FailNow("unexpected error: %v", err)
 	}
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "group-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "group-service-3", capi.HealthCritical)
 
 	// TODO(tgross) ...
 	// Restart client: verify that checks are re-registered
@@ -99,78 +100,82 @@ func (tc *ScriptChecksE2ETest) TestGroupScriptCheck(f *framework.F) {
 // and associated script checks. It updates, stops, etc. the job to verify
 // that script checks are re-registered as expected.
 func (tc *ScriptChecksE2ETest) TestTaskScriptCheck(f *framework.F) {
+	r := require.New(f.T())
+
 	nomadClient := tc.Nomad()
-	uuid := uuid.Generate()
-	require := require.New(f.T())
 	consulClient := tc.Consul()
 
-	jobId := "checks_task" + uuid[0:8]
+	jobId := "checks_task" + uuid.Short()
 	tc.jobIds = append(tc.jobIds, jobId)
 
 	// Job run: verify that checks were registered in Consul
 	allocs := e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_task.nomad", jobId, "")
-	require.Equal(1, len(allocs))
+	r.Equal(1, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-3", capi.HealthCritical)
 
 	// Check in warning state becomes healthy after check passes
 	_, _, err := exec(nomadClient, allocs,
 		[]string{"/bin/sh", "-c", "touch ${NOMAD_TASK_DIR}/alive-2b"})
-	require.NoError(err)
+	r.NoError(err)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-2", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-2", capi.HealthPassing)
 
 	// Job update: verify checks are re-registered in Consul
 	allocs = e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_task_update.nomad", jobId, "")
-	require.Equal(1, len(allocs))
+	r.Equal(1, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-2", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-2", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-3", capi.HealthCritical)
 
 	// Verify we don't have any linger script checks running on the client
 	out, _, err := exec(nomadClient, allocs, []string{"pgrep", "sleep"})
-	require.NoError(err)
+	r.NoError(err)
 	running := strings.Split(strings.TrimSpace(out.String()), "\n")
-	require.LessOrEqual(len(running), 2) // task itself + 1 check == 2
+	r.LessOrEqual(len(running), 2) // task itself + 1 check == 2
 
 	// Clean job stop: verify that checks were deregistered in Consul
-	nomadClient.Jobs().Deregister(jobId, false, nil) // nomad job stop
+	_, _, err = nomadClient.Jobs().Deregister(jobId, false, nil) // nomad job stop
-	e2eutil.RequireConsulDeregistered(require, consulClient, "task-service-1")
+	r.NoError(err)
-	e2eutil.RequireConsulDeregistered(require, consulClient, "task-service-2")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "task-service-1")
-	e2eutil.RequireConsulDeregistered(require, consulClient, "task-service-3")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "task-service-2")
+	e2eutil.RequireConsulDeregistered(r, consulClient, "task-service-3")
 
 	// Restore for next test
 	allocs = e2eutil.RegisterAndWaitForAllocs(f.T(),
 		nomadClient, "consul/input/checks_task.nomad", jobId, "")
-	require.Equal(2, len(allocs))
+	r.Equal(2, len(allocs))
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-3", capi.HealthCritical)
 
 	// Crash a task: verify that checks become healthy again
 	_, _, err = exec(nomadClient, allocs, []string{"pkill", "sleep"})
 	if err != nil && err.Error() != "plugin is shut down" {
-		require.FailNow("unexpected error: %v", err)
+		r.FailNow("unexpected error: %v", err)
 	}
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-1", capi.HealthPassing)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-1", capi.HealthPassing)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-2", capi.HealthWarning)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-2", capi.HealthWarning)
-	e2eutil.RequireConsulStatus(require, consulClient, "task-service-3", capi.HealthCritical)
+	e2eutil.RequireConsulStatus(r, consulClient, "task-service-3", capi.HealthCritical)
 
 	// TODO(tgross) ...
 	// Restart client: verify that checks are re-registered
 }
 
 func (tc *ScriptChecksE2ETest) AfterEach(f *framework.F) {
+	r := require.New(f.T())
+
 	nomadClient := tc.Nomad()
 	jobs := nomadClient.Jobs()
 	// Stop all jobs in test
 	for _, id := range tc.jobIds {
-		jobs.Deregister(id, true, nil)
+		_, _, err := jobs.Deregister(id, true, nil)
+		r.NoError(err)
 	}
 	// Garbage collect
-	nomadClient.System().GarbageCollect()
+	r.NoError(nomadClient.System().GarbageCollect())
 }
 
 func exec(client *api.Client, allocs []*api.AllocationListStub, command []string) (bytes.Buffer, bytes.Buffer, error) {

e2e/e2eutil/consul.go

@@ -7,10 +7,8 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// RequireConsulStatus asserts the aggregate health of the service converges to
+// RequireConsulStatus asserts the aggregate health of the service converges to the expected status.
-// the expected status
+func RequireConsulStatus(require *require.Assertions, client *capi.Client, serviceName, expectedStatus string) {
-func RequireConsulStatus(require *require.Assertions,
-	client *capi.Client, serviceName, expectedStatus string) {
 	require.Eventually(func() bool {
 		_, status := serviceStatus(require, client, serviceName)
 		return status == expectedStatus
@@ -20,10 +18,8 @@ func RequireConsulStatus(require *require.Assertions,
 	)
 }
 
-// serviceStatus gets the aggregate health of the service and returns
+// serviceStatus gets the aggregate health of the service and returns the []ServiceEntry for further checking.
-// the []ServiceEntry for further checking
+func serviceStatus(require *require.Assertions, client *capi.Client, serviceName string) ([]*capi.ServiceEntry, string) {
-func serviceStatus(require *require.Assertions,
-	client *capi.Client, serviceName string) ([]*capi.ServiceEntry, string) {
 	services, _, err := client.Health().Service(serviceName, "", false, nil)
 	require.NoError(err, "expected no error for %q, got %v", serviceName, err)
 	if len(services) > 0 {
@@ -32,12 +28,20 @@ func serviceStatus(require *require.Assertions,
 	return nil, "(unknown status)"
 }
 
-// RequireConsulDeregistered asserts that the service eventually is deregistered from Consul
+// RequireConsulDeregistered asserts that the service eventually is de-registered from Consul.
-func RequireConsulDeregistered(require *require.Assertions,
+func RequireConsulDeregistered(require *require.Assertions, client *capi.Client, service string) {
-	client *capi.Client, serviceName string) {
 	require.Eventually(func() bool {
-		services, _, err := client.Health().Service(serviceName, "", false, nil)
+		services, _, err := client.Health().Service(service, "", false, nil)
-		require.NoError(err, "expected no error for %q, got %v", serviceName, err)
+		require.NoError(err)
 		return len(services) == 0
 	}, 5*time.Second, time.Second)
 }
+
+// RequireConsulRegistered assert that the service is registered in Consul.
+func RequireConsulRegistered(require *require.Assertions, client *capi.Client, service string, count int) {
+	require.Eventually(func() bool {
+		services, _, err := client.Catalog().Service(service, "", nil)
+		require.NoError(err)
+		return len(services) == count
+	}, 5*time.Second, time.Second)
+}

helper/uuid/uuid.go

@@ -1,14 +1,14 @@
 package uuid
 
 import (
-	crand "crypto/rand"
+	"crypto/rand"
 	"fmt"
 )
 
-// Generate is used to generate a random UUID
+// Generate is used to generate a random UUID.
 func Generate() string {
 	buf := make([]byte, 16)
-	if _, err := crand.Read(buf); err != nil {
+	if _, err := rand.Read(buf); err != nil {
 		panic(fmt.Errorf("failed to read random bytes: %v", err))
 	}
 
@@ -19,3 +19,8 @@ func Generate() string {
 		buf[8:10],
 		buf[10:16])
 }
+
+// Short is used to generate the first 8 characters of a UUID.
+func Short() string {
+	return Generate()[0:8]
+}