packer: log plugins used and their version/path

As maintainers of Packer and plugins, we ask our users to provide us
with the versions of Packer and the plugins they use when they open an
issue for us to review.

This is often misunderstood, and may be hidden in the logs, making it
harder for all of us to understand where to look.

This commit adds a log statement that reports the list of plugins used,
their version, and the path they've been loaded from.

bundled_plugin_versions.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	_ "embed"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+
+	"github.com/hashicorp/packer/packer"
+	"golang.org/x/mod/modfile"
+)
+
+//go:embed go.mod
+var mod string
+
+var pluginRegex = regexp.MustCompile("packer-plugin-.*$")
+
+func GetBundledPluginVersions() map[string]packer.PluginSpec {
+	pluginSpecs := map[string]packer.PluginSpec{}
+
+	mods, err := modfile.Parse("", []byte(mod), nil)
+	if err != nil {
+		panic(fmt.Sprintf("failed to parse embedded modfile: %s", err))
+	}
+
+	for _, req := range mods.Require {
+		if pluginRegex.MatchString(req.Mod.Path) {
+			pluginName := pluginRegex.FindString(req.Mod.Path)
+			pluginShortName := strings.Replace(pluginName, "packer-plugin-", "", 1)
+			pluginSpecs[pluginShortName] = packer.PluginSpec{
+				Name:    pluginShortName,
+				Version: fmt.Sprintf("bundled (%s)", req.Mod.Version),
+				Path:    os.Args[0],
+			}
+		}
+	}
+
+	return pluginSpecs
+}

command/build.go

@@ -101,6 +101,8 @@ func (c *BuildCommand) RunContext(buildCtx context.Context, cla *BuildArgs) int
 		return ret
 	}
 
+	c.LogPluginUsage(packerStarter)
+
 	hcpRegistry, diags := registry.New(packerStarter, c.Ui)
 	ret = writeDiags(c.Ui, nil, diags)
 	if ret != 0 {

command/meta.go

@@ -8,7 +8,9 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"log"
 	"os"
+	"sort"
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
@@ -257,7 +259,9 @@ func (m *Meta) detectBundledPluginsJSON(core *packer.Core) []string {
 		}
 	}
 
-	return compileBundledPluginList(bundledPlugins)
+	bundledPluginList := compileBundledPluginList(bundledPlugins)
+
+	return bundledPluginList
 }
 
 var knownPluginPrefixes = map[string]string{
@@ -354,5 +358,110 @@ func (m *Meta) detectBundledPluginsHCL2(config *hcl2template.PackerConfig) []str
 		}
 	}
 
-	return compileBundledPluginList(bundledPlugins)
+	bundledPluginList := compileBundledPluginList(bundledPlugins)
+
+	return bundledPluginList
+}
+
+func (m *Meta) LogPluginUsage(handler packer.Handler) {
+	switch h := handler.(type) {
+	case *packer.Core:
+		m.logPluginUsageJSON(h)
+	case *hcl2template.PackerConfig:
+		m.logPluginUsageHCL2(handler.(*hcl2template.PackerConfig))
+	}
+}
+
+func (m *Meta) logPluginUsageJSON(c *packer.Core) {
+	usedPlugins := map[string]packer.PluginSpec{}
+
+	tmpl := c.Template
+	if tmpl == nil {
+		panic("No template parsed. This is a Packer bug which should be reported, please open an issue on the project's issue tracker.")
+	}
+
+	for _, b := range tmpl.Builders {
+		// Check since internal components are not registered as components
+		ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(b.Type)
+		if ok {
+			usedPlugins[ps.Name] = ps
+		}
+	}
+
+	for _, p := range tmpl.Provisioners {
+		// Check since internal components are not registered as components
+		ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(p.Type)
+		if ok {
+			usedPlugins[ps.Name] = ps
+		}
+	}
+
+	for _, pps := range tmpl.PostProcessors {
+		for _, pp := range pps {
+			// Check since internal components are not registered as components
+			ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(pp.Type)
+			if ok {
+				usedPlugins[ps.Name] = ps
+			}
+		}
+	}
+
+	logPlugins(usedPlugins)
+}
+
+func (m *Meta) logPluginUsageHCL2(config *hcl2template.PackerConfig) {
+	usedPlugins := map[string]packer.PluginSpec{}
+
+	for _, b := range config.Builds {
+		for _, src := range b.Sources {
+			ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(src.Type)
+			if ok {
+				usedPlugins[ps.Name] = ps
+			}
+		}
+
+		for _, p := range b.ProvisionerBlocks {
+			ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(p.PType)
+			if ok {
+				usedPlugins[ps.Name] = ps
+			}
+		}
+
+		for _, pps := range b.PostProcessorsLists {
+			for _, pp := range pps {
+				ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(pp.PType)
+				if ok {
+					usedPlugins[ps.Name] = ps
+				}
+			}
+		}
+	}
+
+	for _, ds := range config.Datasources {
+		ps, ok := m.CoreConfig.Components.PluginConfig.GetSpecForPlugin(ds.Type)
+		if ok {
+			usedPlugins[ps.Name] = ps
+		}
+	}
+
+	logPlugins(usedPlugins)
+}
+
+func logPlugins(usedPlugins map[string]packer.PluginSpec) {
+	// Could happen if no plugin is loaded and we only rely on internal components
+	if len(usedPlugins) == 0 {
+		return
+	}
+
+	pluginNames := make([]string, 0, len(usedPlugins))
+	for pn := range usedPlugins {
+		pluginNames = append(pluginNames, pn)
+	}
+	sort.Strings(pluginNames)
+
+	log.Printf("[INFO] - Used plugins")
+	for _, pn := range pluginNames {
+		ps := usedPlugins[pn]
+		log.Printf(fmt.Sprintf("*\t%s - %s: %s", ps.Name, ps.Version, ps.Path))
+	}
 }

command/validate.go

@@ -81,6 +81,8 @@ func (c *ValidateCommand) RunContext(ctx context.Context, cla *ValidateArgs) int
 		return ret
 	}
 
+	c.LogPluginUsage(packerStarter)
+
 	_, diags = packerStarter.GetBuilds(packer.GetBuildsOptions{
 		Only:   cla.Only,
 		Except: cla.Except,

main.go

@@ -325,7 +325,6 @@ func loadConfig() (*config, error) {
 		PluginMinPort:      10000,
 		PluginMaxPort:      25000,
 		KnownPluginFolders: packer.PluginFolders("."),
-
 		// BuilderRedirects
 		BuilderRedirects: map[string]string{
 
@@ -391,7 +390,13 @@ func loadConfig() (*config, error) {
 			//"vsphere":          "github.com/hashicorp/vsphere",
 			//"vsphere-template": "github.com/hashicorp/vsphere",
 		},
+		PluginComponents: map[string]packer.PluginSpec{},
+	}
+	bundledPlugins := GetBundledPluginVersions()
+	for pn, ps := range bundledPlugins {
+		config.Plugins.PluginComponents[pn] = ps
 	}
+
 	if err := config.Plugins.Discover(); err != nil {
 		return nil, err
 	}

packer/plugin.go

@@ -25,6 +25,20 @@ var defaultChecksummer = plugingetter.Checksummer{
 	Hash: sha256.New(),
 }
 
+type PluginSpec struct {
+	Name    string
+	Path    string
+	Version string
+}
+
+func (ps PluginSpec) String() string {
+	return fmt.Sprintf(`
+Plugin: %s
+Path: %s
+Version: %s`,
+		ps.Name, ps.Path, ps.Version)
+}
+
 // PluginConfig helps load and use packer plugins
 type PluginConfig struct {
 	KnownPluginFolders []string
@@ -51,6 +65,50 @@ type PluginConfig struct {
 	DatasourceRedirects    map[string]string
 	ProvisionerRedirects   map[string]string
 	PostProcessorRedirects map[string]string
+	PluginComponents       map[string]PluginSpec
+}
+
+// GetSpecForComponent returns a pluginspec if the component requested exists in the loaded plugin specs
+//
+// If it does not, the returned boolean will be false.
+func (c PluginConfig) GetSpecForPlugin(name string) (PluginSpec, bool) {
+	names := getPartsFromComponent(name)
+
+	for _, name := range names {
+		pc, ok := c.PluginComponents[name]
+		if ok {
+			return pc, true
+		}
+	}
+
+	return PluginSpec{}, false
+}
+
+// getPartsFromComponent splits the plugin on '-' and returns a list of potential names
+// starting from the longest, and ending on the shortest.
+//
+// Ex:
+// ```go
+//
+//	getPartsFromComponent("plugin-name-component-name") => [
+//		"plugin-name-component-name",
+//		"plugin-name-component",
+//		"plugin-name",
+//		"plugin",
+//	]
+//
+// ```
+func getPartsFromComponent(name string) []string {
+	rets := []string{}
+
+	parts := strings.Split(name, "-")
+
+	for len(parts) > 0 {
+		rets = append(rets, strings.Join(parts, "-"))
+		parts = parts[:len(parts)-1]
+	}
+
+	return rets
 }
 
 // PACKERSPACE is used to represent the spaces that separate args for a command
@@ -280,6 +338,12 @@ func (c *PluginConfig) DiscoverMultiPlugin(pluginName, pluginPath string) error
 		return err
 	}
 
+	pluginSpec := PluginSpec{
+		Name:    pluginName,
+		Path:    pluginPath,
+		Version: desc.Version,
+	}
+
 	pluginPrefix := pluginName + "-"
 
 	for _, builderName := range desc.Builders {
@@ -340,6 +404,8 @@ func (c *PluginConfig) DiscoverMultiPlugin(pluginName, pluginPath string) error
 		log.Printf("found external %v datasource from %s plugin", desc.Datasources, pluginName)
 	}
 
+	c.PluginComponents[pluginName] = pluginSpec
+
 	return nil
 }