Add path attribute to required plugins

hcl2template/plugin.go

@@ -41,6 +41,10 @@ func (cfg *PackerConfig) PluginRequirements() (plugingetter.Requirements, hcl.Di
 				continue
 			}
 
+			if block.Path != "" {
+				continue
+			}
+
 			reqs = append(reqs, &plugingetter.Requirement{
 				Accessor:           name,
 				Identifier:         block.Type,
@@ -54,6 +58,19 @@ func (cfg *PackerConfig) PluginRequirements() (plugingetter.Requirements, hcl.Di
 	return reqs, diags
 }
 
+func (cfg *PackerConfig) getLocalPlugins() []*RequiredPlugin {
+	reqs := []*RequiredPlugin{}
+	for _, block := range cfg.Packer.RequiredPlugins {
+		for _, reqPlugin := range block.RequiredPlugins {
+			if reqPlugin.Path != "" {
+				reqs = append(reqs, reqPlugin)
+			}
+		}
+	}
+
+	return reqs
+}
+
 func (cfg *PackerConfig) DetectPluginBinaries() hcl.Diagnostics {
 	opts := plugingetter.ListInstallationsOptions{
 		FromFolders: cfg.parser.PluginConfig.KnownPluginFolders,
@@ -106,6 +123,21 @@ func (cfg *PackerConfig) DetectPluginBinaries() hcl.Diagnostics {
 		}
 	}
 
+	localPlugins := cfg.getLocalPlugins()
+	for _, local := range localPlugins {
+		err := cfg.parser.PluginConfig.DiscoverMultiPlugin(local.Name, local.Path)
+		if err != nil {
+			diags = diags.Append(&hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  "Failed to load required plugin",
+				Detail: fmt.Sprintf("The required plugin %q, failed to be loaded from path %q: %s",
+					local.Name,
+					local.Path,
+					err),
+			})
+		}
+	}
+
 	if len(uninstalledPlugins) > 0 {
 		detailMessage := &strings.Builder{}
 		detailMessage.WriteString("The following plugins are required, but not installed:\n\n")

hcl2template/types.required_plugins.go

@@ -5,6 +5,7 @@ package hcl2template
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/hashicorp/go-version"
 	"github.com/hashicorp/hcl/v2"
@@ -51,7 +52,10 @@ type RequiredPlugin struct {
 	// for example, "awesomecloud" instead of github.com/awesome/awesomecloud.
 	// This one is left here in case we want to go back to allowing inexplicit
 	// source url definitions.
-	Source      string
+	Source string
+	// Path supersedes every other attribute if specified, and will load the
+	// plugin from the local path specified.
+	Path        string
 	Type        *addrs.Plugin
 	Requirement VersionConstraint
 	DeclRange   hcl.Range
@@ -103,6 +107,42 @@ func decodeRequiredPluginsBlock(block *hcl.Block) (*RequiredPlugins, hcl.Diagnos
 			continue
 
 		case expr.Type().IsObjectType():
+			if expr.Type().HasAttribute("path") {
+				path := expr.GetAttr("path")
+
+				if !path.Type().Equals(cty.String) || path.IsNull() {
+					diags = diags.Append(&hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  `Invalid "path" value`,
+						Detail:   `Path must be specified as a string. For example: path = "./packer-plugin-example"`,
+						Subject:  attr.Expr.Range().Ptr(),
+					})
+					break
+				}
+
+				rp.Path = path.AsString()
+
+				_, err := os.Stat(rp.Path)
+				if err != nil {
+					diags = diags.Append(&hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  "Plugin not found",
+						Detail:   fmt.Sprintf("The plugin %q could not be found at path %q: %s", attr.Name, rp.Path, err),
+						Subject:  attr.Expr.Range().Ptr(),
+					})
+				}
+
+				diags = diags.Append(&hcl.Diagnostic{
+					Severity: hcl.DiagWarning,
+					Summary:  "Loading plugin from local path",
+					Detail: fmt.Sprintf("The plugin %q is loaded from a local path %q. "+
+						"This reduces the portability of the template, and thus should"+
+						" only be used for local testing.", attr.Name, rp.Path),
+				})
+
+				break
+			}
+
 			if !expr.Type().HasAttribute("version") {
 				diags = append(diags, &hcl.Diagnostic{
 					Severity: hcl.DiagError,
@@ -182,18 +222,17 @@ func decodeRequiredPluginsBlock(block *hcl.Block) (*RequiredPlugins, hcl.Diagnos
 
 			attrTypes := expr.Type().AttributeTypes()
 			for name := range attrTypes {
-				if name == "version" || name == "source" {
+				if name == "version" || name == "source" || name == "path" {
 					continue
 				}
 				diags = append(diags, &hcl.Diagnostic{
 					Severity: hcl.DiagError,
 					Summary:  "Invalid required_plugins object",
-					Detail:   `required_plugins objects can only contain "version" and "source" attributes.`,
+					Detail:   `required_plugins objects can only contain "version", "source" or "path" attributes.`,
 					Subject:  attr.Expr.Range().Ptr(),
 				})
 				break
 			}
-
 		default:
 			// should not happen
 			diags = append(diags, &hcl.Diagnostic{

hcl2template/types.required_plugins_test.go

@@ -130,6 +130,47 @@ func TestPackerConfig_required_plugin_parse(t *testing.T) {
 					RequiredPlugins: nil,
 				},
 			}},
+		{
+			name: "test-path-nonexistent-plugin",
+			cfg: PackerConfig{
+				parser: getBasicParser(func(p *Parser) {}),
+			},
+			requirePlugins: `
+			packer {
+				required_plugins {
+					unknown = {
+						path = "./invalid"
+					}
+				}
+			}
+			`,
+			restOfTemplate: `
+			source "null" "test" {
+				communicator = "none"
+			}
+			build {
+				sources = ["null.test"]
+			}
+			`,
+			wantDiags: true,
+			wantConfig: PackerConfig{
+				Packer: struct {
+					VersionConstraints []VersionConstraint
+					RequiredPlugins    []*RequiredPlugins
+				}{
+					RequiredPlugins: []*RequiredPlugins{
+						{
+							RequiredPlugins: map[string]*RequiredPlugin{
+								"unknown": {
+									Name: "unknown",
+									Path: "./invalid",
+								},
+							},
+						},
+					},
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -138,7 +179,9 @@ func TestPackerConfig_required_plugin_parse(t *testing.T) {
 			if len(diags) > 0 {
 				t.Fatal(diags)
 			}
-			if diags := cfg.decodeRequiredPluginsBlock(file); len(diags) > 0 {
+
+			diags = cfg.decodeRequiredPluginsBlock(file)
+			if !tt.wantDiags && len(diags) > 0 {
 				t.Fatal(diags)
 			}