job: add support for job submissions (#405)

If available, use the job submission source to detect changes to
`jobspec`. This can mitigate drift detection problems such as #1.

Read HCL2 variables from job submission even if the `nomad_job` resource
does not speify an `hcl2` block.

CHANGELOG.md

@@ -8,6 +8,7 @@ IMPROVEMENTS:
 * resource/nomad_csi_volume: update import key to be `<volume id>@<namespace>` to allow importing volumes from namespaces other than `default` ([#408](https://github.com/hashicorp/terraform-provider-nomad/pull/408))
 * resource/nomad_csi_volume_registration: update import key to be `<volume id>@<namespace>` to allow importing volume registrations from namespaces other than `default` ([#408](https://github.com/hashicorp/terraform-provider-nomad/pull/408))
   on Nomad version 1.6.3 or later, if the CSI plugin supports it ([#382](https://github.com/hashicorp/terraform-provider-nomad/pull/382))
+* resource/nomad_job: read and submit original jobspec on state refresh and job register ([#405](https://github.com/hashicorp/terraform-provider-nomad/pull/405))
 * resource/nomad_job: Add `rerun_if_dead` attribute to allow forcing a job to run again if it's marked as `dead`. ([#407](https://github.com/hashicorp/terraform-provider-nomad/pull/407))
 * resource/nomad_job: update import key to be `<job id>@<namespace>` to allow importing jobs from namespaces other than `default` ([#408](https://github.com/hashicorp/terraform-provider-nomad/pull/408))
 

nomad/resource_job.go

@@ -19,6 +19,8 @@ import (
 	"github.com/hashicorp/nomad/jobspec2"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/resource"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"golang.org/x/exp/maps"
+
 	"github.com/hashicorp/terraform-provider-nomad/nomad/helper"
 )
 
@@ -351,6 +353,11 @@ type HCL1JobParserConfig struct {
 type HCL2JobParserConfig struct {
 	AllowFS bool
 	Vars    map[string]string
+
+	// Deprecated: Starting in v2.0.0 the provider assumes HCL2 parsing by
+	// default. This field should only be used to update the `hcl2` attribute
+	// in state without causing a diff.
+	Enabled bool
 }
 
 // ResourceFieldGetter are able to retrieve field values.
@@ -407,9 +414,23 @@ func resourceJobRegister(d *schema.ResourceData, meta interface{}) error {
 	if err != nil {
 		wantModifyIndex = 0
 	}
+
+	sub := &api.JobSubmission{
+		Source:        jobspecRaw,
+		Format:        "hcl2",
+		VariableFlags: jobParserConfig.HCL2.Vars,
+	}
+	switch {
+	case jobParserConfig.JSON.Enabled:
+		sub.Format = "json"
+	case jobParserConfig.HCL1.Enabled:
+		sub.Format = "hcl1"
+	}
+
 	resp, _, err := client.Jobs().RegisterOpts(job, &api.RegisterOptions{
 		PolicyOverride: d.Get("policy_override").(bool),
 		ModifyIndex:    wantModifyIndex,
+		Submission:     sub,
 	}, &api.WriteOptions{
 		Namespace: *job.Namespace,
 	})
@@ -641,6 +662,56 @@ func resourceJobRead(d *schema.ResourceData, meta interface{}) error {
 		d.Set("allocation_ids", nil)
 	}
 
+	// Update jobspec submission data if available.
+	// Safely ignore errors as this is an optional step.
+	sub, _, err := client.Jobs().Submission(*job.ID, int(*job.Version), opts)
+	if err != nil {
+		log.Printf("[WARN] failed to read job submission: %v", err)
+	} else {
+		err := resourceJobReadSubmission(sub, d, meta)
+		if err != nil {
+			log.Printf("[WARN] failed to update job submission: %v", err)
+		}
+	}
+
+	return nil
+}
+
+func resourceJobReadSubmission(sub *api.JobSubmission, d *schema.ResourceData, meta any) error {
+	if sub == nil {
+		return nil
+	}
+
+	if sub.Source != "" {
+		d.Set("jobspec", sub.Source)
+	}
+
+	if sub.Format == "hcl2" {
+		var err error
+		var hcl2Config HCL2JobParserConfig
+
+		hcl2, ok := d.GetOk("hcl2")
+		if ok {
+			hcl2Config, err = parseHCL2JobParserConfig(hcl2)
+			if err != nil {
+				return fmt.Errorf("failed to parse HCL2 config: %v", err)
+			}
+		} else {
+			// Use default values if hcl2 is not set.
+			hcl2Config = HCL2JobParserConfig{
+				AllowFS: false,
+				Enabled: true,
+			}
+		}
+
+		// Only update hcl2 if there are changes to variables to avoid
+		// unnecessary updates if hcl2 is not set.
+		if !maps.Equal(sub.VariableFlags, hcl2Config.Vars) {
+			hcl2Config.Vars = sub.VariableFlags
+			d.Set("hcl2", flattenHCL2JobParserConfig(hcl2Config))
+		}
+	}
+
 	return nil
 }
 
@@ -827,6 +898,9 @@ func parseHCL2JobParserConfig(raw interface{}) (HCL2JobParserConfig, error) {
 	if allowFS, ok := hcl2Map["allow_fs"].(bool); ok {
 		config.AllowFS = allowFS
 	}
+	if enabled, ok := hcl2Map["enabled"].(bool); ok {
+		config.Enabled = enabled
+	}
 	if vars, ok := hcl2Map["vars"].(map[string]interface{}); ok {
 		config.Vars = make(map[string]string)
 		for k, v := range vars {
@@ -837,6 +911,14 @@ func parseHCL2JobParserConfig(raw interface{}) (HCL2JobParserConfig, error) {
 	return config, nil
 }
 
+func flattenHCL2JobParserConfig(c HCL2JobParserConfig) []any {
+	return []any{map[string]any{
+		"allow_fs": c.AllowFS,
+		"enabled":  c.Enabled,
+		"vars":     c.Vars,
+	}}
+}
+
 func parseJobspec(raw string, config JobParserConfig, vaultToken *string, consulToken *string) (*api.Job, error) {
 	var job *api.Job
 	var err error

nomad/resource_job_test.go

@@ -7,7 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"reflect"
 	"regexp"
 	"strings"
@@ -641,7 +641,7 @@ func testResourceJob_hcl2Check(s *terraform.State) error {
 	}
 	got := *tpl.EmbeddedTmpl
 
-	want, err := ioutil.ReadFile("./test-fixtures/hello.txt")
+	want, err := os.ReadFile("./test-fixtures/hello.txt")
 	if err != nil {
 		return fmt.Errorf("failed to open template data: %v", err)
 	}
@@ -650,6 +650,28 @@ func testResourceJob_hcl2Check(s *terraform.State) error {
 		return fmt.Errorf("template content mismatch (-want +got):\n%s", diff)
 	}
 
+	sub, _, err := client.Jobs().Submission(jobID, int(*job.Version), &api.QueryOptions{
+		Namespace: *job.Namespace,
+	})
+	if err != nil {
+		return fmt.Errorf("error reading job submissions: %s", err)
+	}
+	if diff := cmp.Diff(instanceState.Attributes["jobspec"], sub.Source); diff != "" {
+		return fmt.Errorf("job source mismatch (-want +got):\n%s", diff)
+	}
+
+	wantVars := make(map[string]string)
+	for k, v := range instanceState.Attributes {
+		if !strings.HasPrefix(k, "hcl2.0.vars") || k == "hcl2.0.vars.%" {
+			continue
+		}
+		varKey := strings.TrimPrefix(k, "hcl2.0.vars.")
+		wantVars[varKey] = v
+	}
+	if diff := cmp.Diff(wantVars, sub.VariableFlags); diff != "" {
+		return fmt.Errorf("job hcl2 variables mismatch (-want +got):\n%s", diff)
+	}
+
 	return nil
 }
 
@@ -1199,6 +1221,16 @@ func testResourceJob_initialCheckNS(t *testing.T, expectedNamespace string) r.Te
 			return fmt.Errorf("job namespace is %q; want %q", got, want)
 		}
 
+		sub, _, err := client.Jobs().Submission(jobID, int(*job.Version), &api.QueryOptions{
+			Namespace: expectedNamespace,
+		})
+		if err != nil {
+			return fmt.Errorf("error reading job submissions: %s", err)
+		}
+		if diff := cmp.Diff(instanceState.Attributes["jobspec"], sub.Source); diff != "" {
+			return fmt.Errorf("job source mismatch (-want +got):\n%s", diff)
+		}
+
 		return nil
 	}
 }

website/docs/r/job.html.markdown

@@ -249,6 +249,13 @@ EOF
 }
 ```
 
+## Tracking Jobspec Changes
+
+The Nomad API allows [submitting the raw jobspec when registering and updating
+jobs](https://developer.hashicorp.com/nomad/api-docs/jobs#submission). If
+available, the job submission source is used to detect changes to the `jobspec`
+and `hcl2.vars` arguments.
+
 ## Argument Reference
 
 The following arguments are supported: