cli-plugins: separate hook types from manager and refactor

cli-plugins/hooks/hook_types.go

@@ -0,0 +1,85 @@
+// FIXME(thaJeztah): remove once we are a module; the go:build directive prevents go from downgrading language version to go1.16:
+//go:build go1.24
+
+// Package hooks defines the contract between the Docker CLI and CLI plugin hook
+// implementations.
+//
+// # Audience
+//
+// This package is intended to be imported by CLI plugin implementations that
+// implement a "hooks" subcommand, and by the Docker CLI when invoking those
+// hooks.
+//
+// # Contract and wire format
+//
+// Hook inputs (see [Request]) are serialized as JSON and passed to the plugin hook
+// subcommand (currently as a command-line argument). Hook outputs are emitted by
+// the plugin as JSON (see [Response]).
+//
+// # Stability
+//
+// The types that represent the hook contract ([Request], [Response] and related
+// constants) are considered part of Docker CLI's public Go API.
+// Fields and values may be extended in a backwards-compatible way (for example,
+// adding new fields), but existing fields and their meaning should remain stable.
+// Plugins should ignore unknown fields and unknown hook types to remain
+// forwards-compatible.
+package hooks
+
+// ResponseType is the type of response from the plugin.
+type ResponseType int
+
+const (
+	NextSteps ResponseType = 0
+)
+
+// Request is the type representing the information
+// that plugins declaring support for hooks get passed when
+// being invoked following a CLI command execution.
+type Request struct {
+	// RootCmd is a string representing the matching hook configuration
+	// which is currently being invoked. If a hook for "docker context"
+	// is configured and the user executes "docker context ls", the plugin
+	// is invoked with "context".
+	RootCmd string `json:"RootCmd,omitzero"`
+
+	// Flags contains flags that were set on the command for which the
+	// hook was invoked. It uses flag names as key, with leading hyphens
+	// removed ("--flag" and "-flag" are included as "flag" and "f").
+	//
+	// Flag values are not included and are set to an empty string,
+	// except for boolean flags known to the CLI itself, for which
+	// the value is either "true", or "false".
+	//
+	// Plugins can use this information to adjust their [Response]
+	// based on whether the command triggering the hook was invoked
+	// with.
+	Flags map[string]string `json:"Flags,omitzero"`
+
+	// CommandError is a string containing the error output (if any)
+	// of the command for which the hook was invoked.
+	CommandError string `json:"CommandError,omitzero"`
+}
+
+// Response represents a plugin hook response. Plugins
+// declaring support for CLI hooks need to print a JSON
+// representation of this type when their hook subcommand
+// is invoked.
+type Response struct {
+	Type     ResponseType `json:"Type"`
+	Template string       `json:"Template,omitzero"`
+}
+
+// HookType is the type of response from the plugin.
+//
+// Deprecated: use [ResponseType] instead.
+//
+//go:fix inline
+type HookType = ResponseType
+
+// HookMessage represents a plugin hook response.
+//
+// Deprecated: use [Response] instead.
+//
+//go:fix inline
+type HookMessage = Response

cli-plugins/hooks/hook_utils.go

@@ -0,0 +1,75 @@
+package hooks
+
+import (
+	"fmt"
+)
+
+const (
+	hookTemplateCommandName = `{{command}}`
+	hookTemplateFlagValue   = `{{flagValue %q}}`
+	hookTemplateArg         = `{{argValue %d}}`
+)
+
+// TemplateReplaceSubcommandName returns a hook template string
+// that will be replaced by the CLI subcommand being executed
+//
+// Example:
+//
+//	Response{
+//		Type:     NextSteps,
+//		Template: "you ran the subcommand: " + TemplateReplaceSubcommandName(),
+//	}
+//
+// When being executed after the command:
+//
+//	docker run --name "my-container" alpine
+//
+// It results in the message:
+//
+//	you ran the subcommand: run
+func TemplateReplaceSubcommandName() string {
+	return hookTemplateCommandName
+}
+
+// TemplateReplaceFlagValue returns a hook template string that will be
+// replaced with the flags value when printed by the CLI.
+//
+// Example:
+//
+//	Response{
+//		Type:     NextSteps,
+//		Template: "you ran a container named: " + TemplateReplaceFlagValue("name"),
+//	}
+//
+// when executed after the command:
+//
+//	docker run --name "my-container" alpine
+//
+// it results in the message:
+//
+//	you ran a container named: my-container
+func TemplateReplaceFlagValue(flag string) string {
+	return fmt.Sprintf(hookTemplateFlagValue, flag)
+}
+
+// TemplateReplaceArg takes an index i and returns a hook
+// template string that the CLI will replace the template with
+// the ith argument after processing the passed flags.
+//
+// Example:
+//
+//	Response{
+//		Type:     NextSteps,
+//		Template: "run this image with `docker run " + TemplateReplaceArg(0) + "`",
+//	}
+//
+// when being executed after the command:
+//
+//	docker pull alpine
+//
+// It results in the message:
+//
+//	Run this image with `docker run alpine`
+func TemplateReplaceArg(i int) string {
+	return fmt.Sprintf(hookTemplateArg, i)
+}

cli-plugins/hooks/hooks_utils_test.go

@@ -0,0 +1,50 @@
+package hooks_test
+
+import (
+	"testing"
+
+	"github.com/docker/cli/cli-plugins/hooks"
+)
+
+func TestTemplateHelpers(t *testing.T) {
+	tests := []struct {
+		doc  string
+		got  func() string
+		want string
+	}{
+		{
+			doc:  "subcommand name",
+			got:  hooks.TemplateReplaceSubcommandName,
+			want: `{{command}}`,
+		},
+		{
+			doc: "flag value",
+			got: func() string {
+				return hooks.TemplateReplaceFlagValue("name")
+			},
+			want: `{{flagValue "name"}}`,
+		},
+		{
+			doc: "arg",
+			got: func() string {
+				return hooks.TemplateReplaceArg(0)
+			},
+			want: `{{argValue 0}}`,
+		},
+		{
+			doc: "arg",
+			got: func() string {
+				return hooks.TemplateReplaceArg(3)
+			},
+			want: `{{argValue 3}}`,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.doc, func(t *testing.T) {
+			if got := tc.got(); got != tc.want {
+				t.Fatalf("expected %q, got %q", tc.want, got)
+			}
+		})
+	}
+}

cli-plugins/hooks/printer.go

@@ -1,18 +1,23 @@
 package hooks
 
-import (
-	"fmt"
-	"io"
+import "io"
 
-	"github.com/morikuni/aec"
+const (
+	whatsNext = "\n\033[1mWhat's next:\033[0m\n"
+	indent    = "    "
 )
 
+// PrintNextSteps renders list of [NextSteps] messages and writes them
+// to out. It is a no-op if messages is empty.
 func PrintNextSteps(out io.Writer, messages []string) {
 	if len(messages) == 0 {
 		return
 	}
-	_, _ = fmt.Fprintln(out, aec.Bold.Apply("\nWhat's next:"))
-	for _, n := range messages {
-		_, _ = fmt.Fprintln(out, "   ", n)
+
+	_, _ = io.WriteString(out, whatsNext)
+	for _, msg := range messages {
+		_, _ = io.WriteString(out, indent)
+		_, _ = io.WriteString(out, msg)
+		_, _ = io.WriteString(out, "\n")
 	}
 }

cli-plugins/hooks/printer_test.go

@@ -1,38 +1,45 @@
-package hooks
+package hooks_test
 
 import (
-	"bytes"
+	"strings"
 	"testing"
 
-	"github.com/morikuni/aec"
+	"github.com/docker/cli/cli-plugins/hooks"
 	"gotest.tools/v3/assert"
 )
 
 func TestPrintHookMessages(t *testing.T) {
-	testCases := []struct {
+	const header = "\n\x1b[1mWhat's next:\x1b[0m\n"
+
+	tests := []struct {
+		doc            string
 		messages       []string
 		expectedOutput string
 	}{
 		{
-			messages:       []string{},
+			doc:            "no messages",
+			messages:       nil,
 			expectedOutput: "",
 		},
 		{
+			doc:      "single message",
 			messages: []string{"Bork!"},
-			expectedOutput: aec.Bold.Apply("\nWhat's next:") + "\n" +
+			expectedOutput: header +
 				"    Bork!\n",
 		},
 		{
+			doc:      "multiple messages",
 			messages: []string{"Foo", "bar"},
-			expectedOutput: aec.Bold.Apply("\nWhat's next:") + "\n" +
+			expectedOutput: header +
 				"    Foo\n" +
 				"    bar\n",
 		},
 	}
-
-	for _, tc := range testCases {
-		w := bytes.Buffer{}
-		PrintNextSteps(&w, tc.messages)
-		assert.Equal(t, w.String(), tc.expectedOutput)
+	for _, tc := range tests {
+		t.Run(tc.doc, func(t *testing.T) {
+			var w strings.Builder
+			hooks.PrintNextSteps(&w, tc.messages)
+			assert.Equal(t, w.String(), tc.expectedOutput)
+		})
 	}
 }