simplify hcl2 parsing helper

No need to pass in the entire eval context

client/allocrunner/taskrunner/task_runner.go

@@ -11,7 +11,6 @@ import (
 	metrics "github.com/armon/go-metrics"
 	log "github.com/hashicorp/go-hclog"
 	multierror "github.com/hashicorp/go-multierror"
-	"github.com/hashicorp/hcl2/hcl"
 	"github.com/hashicorp/hcl2/hcldec"
 	"github.com/hashicorp/nomad/client/allocdir"
 	"github.com/hashicorp/nomad/client/allocrunner/interfaces"
@@ -620,12 +619,7 @@ func (tr *TaskRunner) runDriver() error {
 		tr.logger.Warn("some environment variables not available for rendering", "keys", strings.Join(keys, ", "))
 	}
 
-	evalCtx := &hcl.EvalContext{
-		Variables: vars,
-		Functions: hclutils.GetStdlibFuncs(),
-	}
-
-	val, diag := hclutils.ParseHclInterface(tr.task.Config, tr.taskSchema, evalCtx)
+	val, diag := hclutils.ParseHclInterface(tr.task.Config, tr.taskSchema, vars)
 	if diag.HasErrors() {
 		return multierror.Append(errors.New("failed to parse config"), diag.Errs()...)
 	}

helper/pluginutils/hclutils/util.go

@@ -15,8 +15,14 @@ import (
 )
 
 // ParseHclInterface is used to convert an interface value representing a hcl2
-// body and return the interpolated value.
-func ParseHclInterface(val interface{}, spec hcldec.Spec, ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
+// body and return the interpolated value. Vars may be nil if there are no
+// variables to interpolate.
+func ParseHclInterface(val interface{}, spec hcldec.Spec, vars map[string]cty.Value) (cty.Value, hcl.Diagnostics) {
+	evalCtx := &hcl.EvalContext{
+		Variables: vars,
+		Functions: GetStdlibFuncs(),
+	}
+
 	// Encode to json
 	var buf bytes.Buffer
 	enc := codec.NewEncoder(&buf, structs.JsonHandle)
@@ -37,7 +43,7 @@ func ParseHclInterface(val interface{}, spec hcldec.Spec, ctx *hcl.EvalContext)
 		return cty.NilVal, diag
 	}
 
-	value, decDiag := hcldec.Decode(hclFile.Body, spec, ctx)
+	value, decDiag := hcldec.Decode(hclFile.Body, spec, evalCtx)
 	diag = diag.Extend(decDiag)
 	if diag.HasErrors() {
 		return cty.NilVal, diag

helper/pluginutils/loader/init.go

@@ -10,7 +10,6 @@ import (
 	multierror "github.com/hashicorp/go-multierror"
 	plugin "github.com/hashicorp/go-plugin"
 	version "github.com/hashicorp/go-version"
-	hcl2 "github.com/hashicorp/hcl2/hcl"
 	"github.com/hashicorp/nomad/helper/pluginutils/hclspecutils"
 	"github.com/hashicorp/nomad/helper/pluginutils/hclutils"
 	"github.com/hashicorp/nomad/nomad/structs/config"
@@ -18,14 +17,6 @@ import (
 	"github.com/zclconf/go-cty/cty/msgpack"
 )
 
-var (
-	// configParseCtx is the context used to parse a plugin's configuration
-	// stanza
-	configParseCtx = &hcl2.EvalContext{
-		Functions: hclutils.GetStdlibFuncs(),
-	}
-)
-
 // validateConfig returns whether or not the configuration is valid
 func validateConfig(config *PluginLoaderConfig) error {
 	var mErr multierror.Error
@@ -466,7 +457,7 @@ func (l *PluginLoader) validatePluginConfig(id PluginID, info *pluginInfo) error
 	}
 
 	// Parse the config using the spec
-	val, diag := hclutils.ParseHclInterface(info.config, spec, configParseCtx)
+	val, diag := hclutils.ParseHclInterface(info.config, spec, nil)
 	if diag.HasErrors() {
 		multierror.Append(&mErr, diag.Errs()...)
 		return multierror.Prefix(&mErr, "failed parsing config:")

plugins/shared/cmd/launcher/command/device.go

@@ -14,7 +14,6 @@ import (
 	plugin "github.com/hashicorp/go-plugin"
 	"github.com/hashicorp/hcl"
 	"github.com/hashicorp/hcl/hcl/ast"
-	hcl2 "github.com/hashicorp/hcl2/hcl"
 	"github.com/hashicorp/hcl2/hcldec"
 	"github.com/hashicorp/nomad/helper/pluginutils/hclspecutils"
 	"github.com/hashicorp/nomad/helper/pluginutils/hclutils"
@@ -197,11 +196,7 @@ func (c *Device) setConfig(spec hcldec.Spec, apiVersion string, config []byte, n
 
 	c.logger.Trace("raw hcl config", "config", hclog.Fmt("% #v", pretty.Formatter(configVal)))
 
-	ctx := &hcl2.EvalContext{
-		Functions: hclutils.GetStdlibFuncs(),
-	}
-
-	val, diag := hclutils.ParseHclInterface(configVal, spec, ctx)
+	val, diag := hclutils.ParseHclInterface(configVal, spec, nil)
 	if diag.HasErrors() {
 		errStr := "failed to parse config"
 		for _, err := range diag.Errs() {