Fixed incorrect handling of missing config with optional args

parser/caller.go

@@ -84,13 +84,11 @@ func (c *Caller) callPlugin(kind, name string, config evaluation.Configuration,
 		return
 	}
 
-	// TODO: check that nil interface values are checked like this everywhere
-	needsConfig := !utils.IsNil(data.ConfigSpec)
-	hasConfig := !utils.IsNil(config)
+	acceptsConfig := !utils.IsNil(data.ConfigSpec)
+	hasConfig := config.Exists()
 
 	var configVal cty.Value
-	switch {
-	case needsConfig && hasConfig: // happy path
+	if acceptsConfig {
 		var stdDiag diagnostics.Diag
 		configVal, stdDiag = config.ParseConfig(data.ConfigSpec)
 		if !diags.Extend(stdDiag) {
@@ -105,20 +103,7 @@ func (c *Caller) callPlugin(kind, name string, config evaluation.Configuration,
 				}
 			}
 		}
-	case !needsConfig && !hasConfig:
-		// happy path, do nothing
-	case needsConfig && !hasConfig:
-		diags.Append(&hcl.Diagnostic{
-			Severity: hcl.DiagError,
-			Summary:  "Plugin requires configuration",
-			Detail: fmt.Sprintf("Plugin '%s %s' has no default configuration and "+
-				"no configuration was provided at the plugin invocation. "+
-				"Provide an inline config block or a config attribute",
-				kind, name),
-			Subject: invocation.MissingItemRange().Ptr(),
-			Context: invocation.Range().Ptr(),
-		})
-	case !needsConfig && hasConfig:
+	} else if hasConfig {
 		diags.Append(&hcl.Diagnostic{
 			Severity: hcl.DiagWarning,
 			Summary:  "Plugin doesn't support configuration",

parser/definedBlocks.go

@@ -69,6 +69,14 @@ func (db *DefinedBlocks) GetConfig(expr hcl.Expression) (cfg *definitions.Config
 	return
 }
 
+func (db *DefinedBlocks) DefaultConfigFor(plugin *definitions.Plugin) (config *definitions.Config) {
+	return db.Config[definitions.Key{
+		PluginKind: plugin.Kind(),
+		PluginName: plugin.Name(),
+		BlockName:  "",
+	}]
+}
+
 func (db *DefinedBlocks) Merge(other *DefinedBlocks) (diags diagnostics.Diag) {
 	for k, v := range other.Config {
 		diags.Append(AddIfMissing(db.Config, k, v))

parser/definitions/config.go

@@ -20,6 +20,11 @@ type Config struct {
 	value      cty.Value
 }
 
+// Exists implements evaluation.Configuration.
+func (c *Config) Exists() bool {
+	return c != nil
+}
+
 var _ evaluation.Configuration = (*Config)(nil)
 
 // ParseConfig implements Configuration.

parser/definitions/configEmpty.go

@@ -0,0 +1,49 @@
+package definitions
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hcldec"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+	"github.com/zclconf/go-cty/cty"
+
+	"github.com/blackstork-io/fabric/parser/evaluation"
+	"github.com/blackstork-io/fabric/pkg/diagnostics"
+)
+
+// Empty config, storing the range of the original block
+type ConfigEmpty struct {
+	MissingItemRange hcl.Range
+}
+
+// Exists implements evaluation.Configuration.
+func (c *ConfigEmpty) Exists() bool {
+	return false
+}
+
+// ParseConfig implements Configuration.
+func (c *ConfigEmpty) ParseConfig(spec hcldec.Spec) (val cty.Value, diags diagnostics.Diag) {
+	emptyBody := &hclsyntax.Body{
+		SrcRange: c.MissingItemRange,
+		EndRange: hcl.Range{
+			Filename: c.MissingItemRange.Filename,
+			Start:    c.MissingItemRange.End,
+			End:      c.MissingItemRange.End,
+		},
+	}
+
+	var diag hcl.Diagnostics
+	val, diag = hcldec.Decode(emptyBody, spec, nil)
+	for _, d := range diag {
+		d.Summary = fmt.Sprintf("Missing required configuration: %s", d.Summary)
+	}
+	return val, diagnostics.Diag(diag)
+}
+
+// Range implements Configuration.
+func (c *ConfigEmpty) Range() hcl.Range {
+	return c.MissingItemRange
+}
+
+var _ evaluation.Configuration = (*ConfigEmpty)(nil)

parser/definitions/configPtr.go

@@ -15,6 +15,11 @@ type ConfigPtr struct {
 	Ptr *hcl.Attribute
 }
 
+// Exists implements evaluation.Configuration.
+func (c *ConfigPtr) Exists() bool {
+	return c != nil
+}
+
 // ParseConfig implements Configuration.
 func (c *ConfigPtr) ParseConfig(spec hcldec.Spec) (val cty.Value, diags diagnostics.Diag) {
 	return c.Cfg.ParseConfig(spec)

parser/evaluation/evaluation.go

@@ -13,6 +13,7 @@ import (
 type Configuration interface {
 	ParseConfig(spec hcldec.Spec) (cty.Value, diagnostics.Diag)
 	Range() hcl.Range
+	Exists() bool
 }
 
 // To act as a plugin invocation (body of the plugin call block)

parser/parsePluginBlock.go

@@ -190,13 +190,13 @@ func (db *DefinedBlocks) parsePluginConfig(plugin *definitions.Plugin, configAtt
 		}
 	} else if plugin.IsRef() {
 		config = refBaseConfig
-	} else {
+	} else if defaultCfg := db.DefaultConfigFor(plugin); defaultCfg != nil {
 		// Apply default configs to non-refs only
-		config = db.Config[definitions.Key{
-			PluginKind: plugin.Kind(),
-			PluginName: plugin.Name(),
-			BlockName:  "",
-		}]
+		config = defaultCfg
+	} else {
+		config = &definitions.ConfigEmpty{
+			MissingItemRange: plugin.Block.Body.MissingItemRange(),
+		}
 	}
 	return
 }