Add Scheduler config resource

nomad/provider.go

@@ -88,6 +88,7 @@ func Provider() terraform.ResourceProvider {
 			"nomad_quota_specification": resourceQuotaSpecification(),
 			"nomad_sentinel_policy":     resourceSentinelPolicy(),
 			"nomad_volume":              resourceVolume(),
+			"nomad_scheduler_config":    resourceSchedulerConfig(),
 		},
 	}
 }

nomad/resource_scheduler_config.go

@@ -0,0 +1,135 @@
+package nomad
+
+import (
+	"errors"
+	"fmt"
+	"log"
+
+	"github.com/hashicorp/nomad/api"
+	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
+	"github.com/hashicorp/terraform-plugin-sdk/helper/validation"
+)
+
+func resourceSchedulerConfig() *schema.Resource {
+	return &schema.Resource{
+		Create: resourceSchedulerConfigurationCreate,
+		Update: resourceSchedulerConfigurationCreate,
+		Delete: resourceSchedulerConfigurationDelete,
+		Read:   resourceSchedulerConfigurationRead,
+
+		Schema: map[string]*schema.Schema{
+			"scheduler_algorithm": {
+				Description: "Specifies whether scheduler binpacks or spreads allocations on available nodes.",
+				Type:        schema.TypeString,
+				Default:     "binpack",
+				Optional:    true,
+				Elem: &schema.Schema{
+					Type: schema.TypeString,
+					ValidateFunc: validation.StringInSlice([]string{
+						"binpack",
+						"spread",
+					}, false),
+				},
+			},
+			// TODO(jrasell) once the Terraform SDK has been updated within
+			//  this provider, we should add validation.MapKeyMatch to this
+			//  schema entry using a regex such as:
+			//  "("^[service,system,batch]_scheduler_enabled")".
+			"preemption_config": {
+				Description: "Options to enable preemption for various schedulers.",
+				Optional:    true,
+				Type:        schema.TypeMap,
+				Elem: &schema.Schema{
+					Type: schema.TypeBool,
+				},
+			},
+		},
+	}
+}
+
+func resourceSchedulerConfigurationCreate(d *schema.ResourceData, meta interface{}) error {
+	client := meta.(ProviderConfig).client
+	operator := client.Operator()
+
+	config := api.SchedulerConfiguration{
+		SchedulerAlgorithm: api.SchedulerAlgorithm(d.Get("scheduler_algorithm").(string)),
+		PreemptionConfig:   api.PreemptionConfig{},
+	}
+
+	// Unpack the preemption block.
+	preempt, ok := d.GetOk("preemption_config")
+	if ok {
+		preemptMap, ok := preempt.(map[string]interface{})
+		if !ok {
+			return errors.New("failed to unpack preemption configuration block")
+		}
+
+		if val, ok := preemptMap["batch_scheduler_enabled"].(bool); ok {
+			config.PreemptionConfig.BatchSchedulerEnabled = val
+		}
+		if val, ok := preemptMap["service_scheduler_enabled"].(bool); ok {
+			config.PreemptionConfig.ServiceSchedulerEnabled = val
+		}
+		if val, ok := preemptMap["system_scheduler_enabled"].(bool); ok {
+			config.PreemptionConfig.SystemSchedulerEnabled = val
+		}
+	}
+
+	// Perform the config write.
+	log.Printf("[DEBUG] Upserting Scheduler configuration")
+	if _, _, err := operator.SchedulerSetConfiguration(&config, nil); err != nil {
+		return fmt.Errorf("error upserting scheduler configuration: %s", err.Error())
+	}
+	log.Printf("[DEBUG] Upserted scheduler configuration")
+
+	return resourceSchedulerConfigurationRead(d, meta)
+}
+
+// resourceSchedulerConfigurationDelete does not do anything:
+//
+// There is not a correct way to destroy this "resource" nor check it was
+// destroyed.
+//
+// Consider the following:
+//   1. an operator manually updates the Nomad scheduler config, or doesn't
+//   2. they decide to move management over to Terraform
+//   3. they get rid of Terraform management
+//
+// If the destroy reverts to the Nomad default configuration, we are over
+// writing changes based on assumption. We cannot go back in time to the
+// initial version as we do not have this information available, so we just
+// have to leave it be.
+func resourceSchedulerConfigurationDelete(_ *schema.ResourceData, _ interface{}) error { return nil }
+
+func resourceSchedulerConfigurationRead(d *schema.ResourceData, meta interface{}) error {
+	client := meta.(ProviderConfig).client
+	operator := client.Operator()
+
+	// The scheduler config doesn't have a UUID, so the resource uses the agent
+	// region. Grab this so we can set it later.
+	reg, err := client.Agent().Region()
+	if err != nil {
+		return fmt.Errorf("error getting region: %s", err.Error())
+	}
+	// retrieve the config
+	log.Printf("[DEBUG] Reading scheduler configuration")
+	config, _, err := operator.SchedulerGetConfiguration(nil)
+	if err != nil {
+		return fmt.Errorf("error reading scheduler configuration: %s", err.Error())
+	}
+	log.Printf("[DEBUG] Read scheduler configuration")
+
+	d.SetId(fmt.Sprintf("nomad-scheduler-configuration-%s", reg))
+
+	// Set the algorithm, handling any error when performing the set.
+	if err := d.Set("scheduler_algorithm", config.SchedulerConfig.SchedulerAlgorithm); err != nil {
+		return err
+	}
+
+	premptMap := map[string]bool{
+		"batch_scheduler_enabled":   config.SchedulerConfig.PreemptionConfig.BatchSchedulerEnabled,
+		"service_scheduler_enabled": config.SchedulerConfig.PreemptionConfig.ServiceSchedulerEnabled,
+		"system_scheduler_enabled":  config.SchedulerConfig.PreemptionConfig.SystemSchedulerEnabled,
+	}
+	return d.Set("preemption_config", premptMap)
+}

nomad/resource_scheduler_config_test.go

@@ -0,0 +1,94 @@
+package nomad
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-sdk/helper/resource"
+	"github.com/hashicorp/terraform-plugin-sdk/terraform"
+)
+
+func TestSchedulerConfig_basic(t *testing.T) {
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testProviders,
+		CheckDestroy: testFinalConfiguration,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccNomadSchedulerConfigSpread,
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"scheduler_algorithm",
+						"spread",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.batch_scheduler_enabled",
+						"true",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.service_scheduler_enabled",
+						"true",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.system_scheduler_enabled",
+						"true",
+					),
+				),
+			},
+			{
+				Config: testAccNomadSchedulerConfigBinpack,
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"scheduler_algorithm",
+						"binpack",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.batch_scheduler_enabled",
+						"false",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.service_scheduler_enabled",
+						"true",
+					),
+					resource.TestCheckResourceAttr(
+						"nomad_scheduler_config.config",
+						"preemption_config.system_scheduler_enabled",
+						"false",
+					),
+				),
+			},
+		},
+	})
+}
+
+const testAccNomadSchedulerConfigSpread = `
+resource "nomad_scheduler_config" "config" {
+	scheduler_algorithm = "spread"
+	preemption_config = {
+		system_scheduler_enabled = true
+		batch_scheduler_enabled = true
+		service_scheduler_enabled = true
+	}
+}
+`
+
+const testAccNomadSchedulerConfigBinpack = `
+resource "nomad_scheduler_config" "config" {
+	scheduler_algorithm = "binpack"
+	preemption_config = {
+		system_scheduler_enabled = false
+		batch_scheduler_enabled = false
+		service_scheduler_enabled = true
+	}
+}
+`
+
+// for details on why this is the way it is, checkout the comments on
+// resourceSchedulerConfigurationDelete.
+func testFinalConfiguration(_ *terraform.State) error { return nil }

website/docs/r/scheduler_config.html.markdown

@@ -0,0 +1,41 @@
+---
+layout: "nomad"
+page_title: "Nomad: nomad_scheduler_config"
+sidebar_current: "docs-nomad-scheduler-config"
+description: |-
+  Manages scheduler configuration on the Nomad server.
+---
+
+# nomad_scheduler_config
+
+Manages scheduler configuration of the Nomad cluster.
+
+~> **Warning:** destroying this resource will not have any effect in the
+cluster configuration, since there's no clear definition of what a destroy
+action should do. The cluster will be left as-is and only the state reference
+will be removed.
+
+## Example Usage
+
+Set cluster scheduler configuration:
+
+```hcl
+resource "nomad_scheduler_config" "config" {
+  scheduler_algorithm = "spread"
+  preemption_config = {
+    system_scheduler_enabled  = true
+    batch_scheduler_enabled   = true
+    service_scheduler_enabled = true
+  }
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+- `algorithm` `(string: "binpack")` - Specifies whether scheduler binpacks or spreads allocations on available nodes. Possible values are `binpack` and `spread`.
+- `preemption_config` `(map[string]bool)` - Options to enable preemption for various schedulers.
+  - `system_scheduler_enabled` `(bool: true)` - Specifies whether preemption for system jobs is enabled. Note that if this is set to true, then system jobs can preempt any other jobs.
+  - `batch_scheduler_enabled` `(bool: false")` - Specifies whether preemption for batch jobs is enabled. Note that if this is set to true, then batch jobs can preempt any other jobs.
+  - `service_scheduler_enabled` `(bool: false)` - Specifies whether preemption for service jobs is enabled. Note that if this is set to true, then service jobs can preempt any other jobs.

website/nomad.erb

@@ -76,6 +76,9 @@
             <li<%= sidebar_current("docs-nomad-resource-sentinel-policy") %>>
               <a href="/docs/providers/nomad/r/sentinel_policy.html">nomad_sentinel_policy</a>
             </li>
+            <li<%= sidebar_current("docs-nomad-resource-scheduler-config") %>>
+              <a href="/docs/providers/nomad/r/scheduler_config.html">nomad_scheduler_config</a>
+            </li>
             <li<%= sidebar_current("docs-nomad-resource-volume-policy") %>>
               <a href="/docs/providers/nomad/r/volume.html">nomad_volume</a>
             </li>