Restrict HCL special casing of map[string]interface{} fields

The HCL2 parser needs to apply special parsing tweaks so it can parse
the task config the same way as HCL1. Particularly, it needs to
reinterprets `map[string]interface{}` fields and blocks that appear when
attributes are expected.

This commit restricts the special casing to the Job fields, and ignore
`variables` and `locals` block.

jobspec2/parse.go

@@ -11,11 +11,9 @@ import (
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
-	"github.com/hashicorp/hcl/v2/ext/dynblock"
 	"github.com/hashicorp/hcl/v2/hclsyntax"
 	hcljson "github.com/hashicorp/hcl/v2/json"
 	"github.com/hashicorp/nomad/api"
-	"github.com/hashicorp/nomad/jobspec2/hclutil"
 )
 
 func Parse(path string, r io.Reader) (*api.Job, error) {
@@ -104,9 +102,7 @@ func decode(c *jobConfig) error {
 		return diags
 	}
 
-	body := hclutil.BlocksAsAttrs(file.Body)
-	body = dynblock.Expand(body, c.EvalContext())
-	diags = c.decodeBody(body)
+	diags = c.decodeBody(file.Body)
 	if diags.HasErrors() {
 		var str strings.Builder
 		for i, diag := range diags {
@@ -117,7 +113,9 @@ func decode(c *jobConfig) error {
 		}
 		return errors.New(str.String())
 	}
-	diags = append(diags, decodeMapInterfaceType(&c, c.EvalContext())...)
+	diags = append(diags, decodeMapInterfaceType(&c.Job, c.EvalContext())...)
+	diags = append(diags, decodeMapInterfaceType(&c.Tasks, c.EvalContext())...)
+	diags = append(diags, decodeMapInterfaceType(&c.Vault, c.EvalContext())...)
 	return nil
 }
 

jobspec2/parse_job.go

@@ -113,6 +113,10 @@ func normalizeTemplates(templates []*api.Template) {
 	}
 }
 
+func intToPtr(v int) *int {
+	return &v
+}
+
 func int8ToPtr(v int8) *int8 {
 	return &v
 }

jobspec2/parse_map.go

@@ -41,6 +41,11 @@ func (w *walker) Map(m reflect.Value) error {
 		return nil
 	}
 
+	// ignore private map fields
+	if !m.CanSet() {
+		return nil
+	}
+
 	for _, k := range m.MapKeys() {
 		v := m.MapIndex(k)
 		if attr, ok := v.Interface().(*hcl.Attribute); ok {

jobspec2/parse_test.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"testing"
 
+	"github.com/hashicorp/nomad/api"
 	"github.com/hashicorp/nomad/jobspec"
 	"github.com/stretchr/testify/require"
 )
@@ -469,3 +470,132 @@ job "example" {
 		})
 	}
 }
+
+func TestParseJob_JobWithFunctionsAndLookups(t *testing.T) {
+	hcl := `
+variable "env" {
+  description = "target environment for the job"
+}
+
+locals {
+  environments = {
+    prod    = { count = 20, dcs = ["prod-dc1", "prod-dc2"] },
+    staging = { count = 3, dcs = ["dc1"] },
+  }
+
+  env = lookup(local.environments, var.env, { count = 0, dcs = [] })
+}
+
+job "job-webserver" {
+  datacenters = local.env.dcs
+  group "group-webserver" {
+    count = local.env.count
+
+    task "server" {
+      driver = "docker"
+
+      config {
+        image = "hashicorp/http-echo"
+        args  = ["-text", "Hello from ${var.env}"]
+      }
+    }
+  }
+}
+`
+	cases := []struct {
+		env         string
+		expectedJob *api.Job
+	}{
+		{
+			"prod",
+			&api.Job{
+				ID:          stringToPtr("job-webserver"),
+				Name:        stringToPtr("job-webserver"),
+				Datacenters: []string{"prod-dc1", "prod-dc2"},
+				TaskGroups: []*api.TaskGroup{
+					{
+						Name:  stringToPtr("group-webserver"),
+						Count: intToPtr(20),
+
+						Tasks: []*api.Task{
+							{
+								Name:   "server",
+								Driver: "docker",
+
+								Config: map[string]interface{}{
+									"image": "hashicorp/http-echo",
+									"args":  []interface{}{"-text", "Hello from prod"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			"staging",
+			&api.Job{
+				ID:          stringToPtr("job-webserver"),
+				Name:        stringToPtr("job-webserver"),
+				Datacenters: []string{"dc1"},
+				TaskGroups: []*api.TaskGroup{
+					{
+						Name:  stringToPtr("group-webserver"),
+						Count: intToPtr(3),
+
+						Tasks: []*api.Task{
+							{
+								Name:   "server",
+								Driver: "docker",
+
+								Config: map[string]interface{}{
+									"image": "hashicorp/http-echo",
+									"args":  []interface{}{"-text", "Hello from staging"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			"unknown",
+			&api.Job{
+				ID:          stringToPtr("job-webserver"),
+				Name:        stringToPtr("job-webserver"),
+				Datacenters: []string{},
+				TaskGroups: []*api.TaskGroup{
+					{
+						Name:  stringToPtr("group-webserver"),
+						Count: intToPtr(0),
+
+						Tasks: []*api.Task{
+							{
+								Name:   "server",
+								Driver: "docker",
+
+								Config: map[string]interface{}{
+									"image": "hashicorp/http-echo",
+									"args":  []interface{}{"-text", "Hello from unknown"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.env, func(t *testing.T) {
+			found, err := ParseWithConfig(&ParseConfig{
+				Path:    "example.hcl",
+				Body:    []byte(hcl),
+				AllowFS: false,
+				ArgVars: []string{"env=" + c.env},
+			})
+			require.NoError(t, err)
+			require.Equal(t, c.expectedJob, found)
+		})
+	}
+}

jobspec2/types.config.go

@@ -5,7 +5,9 @@ import (
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/ext/dynblock"
 	"github.com/hashicorp/nomad/api"
+	"github.com/hashicorp/nomad/jobspec2/hclutil"
 	"github.com/zclconf/go-cty/cty"
 )
 
@@ -240,6 +242,9 @@ func (c *jobConfig) decodeJob(content *hcl.BodyContent, ctx *hcl.EvalContext) hc
 			continue
 		}
 
+		body := hclutil.BlocksAsAttrs(b.Body)
+		body = dynblock.Expand(body, ctx)
+
 		if found != nil {
 			diags = append(diags, &hcl.Diagnostic{
 				Severity: hcl.DiagError,
@@ -256,12 +261,13 @@ func (c *jobConfig) decodeJob(content *hcl.BodyContent, ctx *hcl.EvalContext) hc
 
 		c.JobID = b.Labels[0]
 
-		extra, remain, mdiags := b.Body.PartialContent(&hcl.BodySchema{
+		extra, remain, mdiags := body.PartialContent(&hcl.BodySchema{
 			Blocks: []hcl.BlockHeaderSchema{
 				{Type: "vault"},
 				{Type: "task", LabelNames: []string{"name"}},
 			},
 		})
+
 		diags = append(diags, mdiags...)
 		diags = append(diags, c.decodeTopLevelExtras(extra, ctx)...)
 		diags = append(diags, hclDecoder.DecodeBody(remain, ctx, c.Job)...)