feat(cli): enable extended client access (#285)

This patch gets rid of the clientMixin in command structs in favor of passing a CmdOptions struct to the New (formerly Builder) function in CmdInfo.

This change allows the client to be extended as shown in the following example:

// Example command implementation

type cmdFoo struct {
        /* ... */
	client *MyClient
}

func init() {
	AddCommand(&CmdInfo{
		/* ... */
		New: func(opts *CmdOptions) flags.Commander {
			return &cmdFoo{client: &MyClient{opts.Client}}
		},
	})
}

func (cmd *cmdFoo) Execute(args []string) error {
        return cmd.client.Foo()
}

// Example client implementation

import "github.com/canonical/pebble/client"

type MyClient struct {
        *client.Client
}

func (c *MyClient) Foo() error {
        /* ... */
}

internals/cli/cli.go

@@ -52,6 +52,12 @@ const defaultPebbleDir = "/var/lib/pebble/default"
 // ErrExtraArgs is returned  if extra arguments to a command are found
 var ErrExtraArgs = fmt.Errorf("too many arguments for command")
 
+// CmdOptions exposes state made accessible during command execution.
+type CmdOptions struct {
+	Client *client.Client
+	Parser *flags.Parser
+}
+
 // CmdInfo holds information needed by the CLI to execute commands and
 // populate entries in the help manual.
 type CmdInfo struct {
@@ -67,9 +73,8 @@ type CmdInfo struct {
 	// command, and in the Pebble man page.
 	Description string
 
-	// Builder is a function that creates a new instance of the command
-	// struct containing an Execute(args []string) implementation.
-	Builder func() flags.Commander
+	// New is a function that creates a new instance of the command.
+	New func(*CmdOptions) flags.Commander
 
 	// ArgsHelp (optional) contains help about the command-line arguments
 	// (including options) supported by the command.
@@ -139,22 +144,6 @@ func fixupArg(optName string) string {
 	return optName
 }
 
-type clientSetter interface {
-	setClient(*client.Client)
-}
-
-type clientMixin struct {
-	client *client.Client
-}
-
-func (ch *clientMixin) setClient(cli *client.Client) {
-	ch.client = cli
-}
-
-type parserSetter interface {
-	setParser(*flags.Parser)
-}
-
 type defaultOptions struct {
 	Version func() `long:"version" hidden:"yes" description:"Print the version and exit"`
 }
@@ -192,13 +181,7 @@ func Parser(cli *client.Client) *flags.Parser {
 
 	// Add all commands
 	for _, c := range commands {
-		obj := c.Builder()
-		if x, ok := obj.(clientSetter); ok {
-			x.setClient(cli)
-		}
-		if x, ok := obj.(parserSetter); ok {
-			x.setParser(parser)
-		}
+		obj := c.New(&CmdOptions{Client: cli, Parser: parser})
 
 		var target *flags.Command
 		if c.Debug {

internals/cli/cmd_add.go

@@ -32,7 +32,8 @@ label (or append if the label is not found).
 `
 
 type cmdAdd struct {
-	clientMixin
+	client *client.Client
+
 	Combine    bool `long:"combine"`
 	Positional struct {
 		Label     string `positional-arg-name:"<label>" required:"1"`
@@ -48,7 +49,9 @@ func init() {
 		ArgsHelp: map[string]string{
 			"--combine": "Combine the new layer with an existing layer that has the given label (default is to append)",
 		},
-		Builder: func() flags.Commander { return &cmdAdd{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdAdd{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_autostart.go

@@ -27,6 +27,8 @@ to start by default.
 `
 
 type cmdAutoStart struct {
+	client *client.Client
+
 	waitMixin
 }
 
@@ -36,7 +38,9 @@ func init() {
 		Summary:     cmdAutoStartSummary,
 		Description: cmdAutoStartDescription,
 		ArgsHelp:    waitArgsHelp,
-		Builder:     func() flags.Commander { return &cmdAutoStart{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdAutoStart{client: opts.Client}
+		},
 	})
 }
 
@@ -51,7 +55,7 @@ func (cmd cmdAutoStart) Execute(args []string) error {
 		return err
 	}
 
-	if _, err := cmd.wait(changeID); err != nil {
+	if _, err := cmd.wait(cmd.client, changeID); err != nil {
 		if err == noWait {
 			return nil
 		}

internals/cli/cmd_changes.go

@@ -30,7 +30,8 @@ The changes command displays a summary of system changes performed recently.
 `
 
 type cmdChanges struct {
-	clientMixin
+	client *client.Client
+
 	timeMixin
 	Positional struct {
 		Service string `positional-arg-name:"<service>"`
@@ -44,6 +45,8 @@ change that happened recently.
 `
 
 type cmdTasks struct {
+	client *client.Client
+
 	timeMixin
 	changeIDMixin
 }
@@ -54,14 +57,18 @@ func init() {
 		Summary:     cmdChangesSummary,
 		Description: cmdChangesDescription,
 		ArgsHelp:    timeArgsHelp,
-		Builder:     func() flags.Commander { return &cmdChanges{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdChanges{client: opts.Client}
+		},
 	})
 	AddCommand(&CmdInfo{
 		Name:        "tasks",
 		Summary:     cmdTasksSummary,
 		Description: cmdTasksDescription,
 		ArgsHelp:    merge(changeIDMixinArgsHelp, timeArgsHelp),
-		Builder:     func() flags.Commander { return &cmdTasks{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdTasks{client: opts.Client}
+		},
 	})
 }
 
@@ -133,7 +140,7 @@ func (c *cmdChanges) Execute(args []string) error {
 }
 
 func (c *cmdTasks) Execute([]string) error {
-	chid, err := c.GetChangeID()
+	chid, err := c.GetChangeID(c.client)
 	if err != nil {
 		if err == noChangeFoundOK {
 			return nil

internals/cli/cmd_checks.go

@@ -30,7 +30,8 @@ arguments.
 `
 
 type cmdChecks struct {
-	clientMixin
+	client *client.Client
+
 	Level      string `long:"level"`
 	Positional struct {
 		Checks []string `positional-arg-name:"<check>"`
@@ -45,7 +46,9 @@ func init() {
 		ArgsHelp: map[string]string{
 			"--level": `Check level to filter for ("alive" or "ready")`,
 		},
-		Builder: func() flags.Commander { return &cmdChecks{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdChecks{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_enter.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/canonical/go-flags"
 
+	"github.com/canonical/pebble/client"
 	"github.com/canonical/pebble/internals/logger"
 )
 
@@ -46,21 +47,24 @@ These subcommands are currently supported:
 `
 
 type cmdEnter struct {
-	clientMixin
+	client *client.Client
+	parser *flags.Parser
+
 	sharedRunEnterOpts
 	Run        bool `long:"run"`
 	Positional struct {
 		Cmd []string `positional-arg-name:"<subcommand>"`
 	} `positional-args:"yes"`
-	parser *flags.Parser
 }
 
 func init() {
 	AddCommand(&CmdInfo{
 		Name:        "enter",
 		Summary:     cmdEnterSummary,
 		Description: cmdEnterDescription,
-		Builder:     func() flags.Commander { return &cmdEnter{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdEnter{client: opts.Client, parser: opts.Parser}
+		},
 		ArgsHelp: merge(sharedRunEnterArgsHelp, map[string]string{
 			"--run": "Start default services before executing subcommand",
 		}),
@@ -104,8 +108,8 @@ func (cmd *cmdEnter) Execute(args []string) error {
 
 	runCmd := cmdRun{
 		sharedRunEnterOpts: cmd.sharedRunEnterOpts,
+		client:             cmd.client,
 	}
-	runCmd.setClient(cmd.client)
 
 	if len(cmd.Positional.Cmd) == 0 {
 		runCmd.run(nil)
@@ -195,7 +199,3 @@ func (cmd *cmdEnter) Execute(args []string) error {
 
 	return err
 }
-
-func (cmd *cmdEnter) setParser(parser *flags.Parser) {
-	cmd.parser = parser
-}

internals/cli/cmd_exec.go

@@ -43,7 +43,8 @@ pebble exec --timeout 10s -- echo -n foo bar
 `
 
 type cmdExec struct {
-	clientMixin
+	client *client.Client
+
 	WorkingDir     string        `short:"w"`
 	Env            []string      `long:"env"`
 	UserID         *int          `long:"uid"`
@@ -81,7 +82,9 @@ func init() {
 			"-I":        "Disable interactive mode and use a pipe for stdin",
 		},
 		PassAfterNonOption: true,
-		Builder:            func() flags.Commander { return &cmdExec{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdExec{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_help.go

@@ -31,12 +31,13 @@ The help command displays information about commands.
 `
 
 type cmdHelp struct {
+	parser *flags.Parser
+
 	All        bool `long:"all"`
 	Manpage    bool `long:"man" hidden:"true"`
 	Positional struct {
 		Subs []string `positional-arg-name:"<command>"`
 	} `positional-args:"yes"`
-	parser *flags.Parser
 }
 
 func init() {
@@ -48,7 +49,9 @@ func init() {
 			"--all": "Show a short summary of all commands",
 			"--man": "Generate the manpage",
 		},
-		Builder: func() flags.Commander { return &cmdHelp{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdHelp{parser: opts.Parser}
+		},
 	})
 }
 

internals/cli/cmd_logs.go

@@ -34,7 +34,8 @@ if none are specified) and displays them in chronological order.
 `
 
 type cmdLogs struct {
-	clientMixin
+	client *client.Client
+
 	Follow     bool   `short:"f" long:"follow"`
 	Format     string `long:"format"`
 	N          string `short:"n"`
@@ -53,7 +54,9 @@ func init() {
 			"--format": "Output format: \"text\" (default) or \"json\" (JSON lines).",
 			"-n":       "Number of logs to show (before following); defaults to 30.\nIf 'all', show all buffered logs.",
 		},
-		Builder: func() flags.Commander { return &cmdLogs{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdLogs{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_ls.go

@@ -33,12 +33,11 @@ may be specified for the last path element.
 `
 
 type cmdLs struct {
-	clientMixin
-	timeMixin
+	client *client.Client
 
+	timeMixin
 	Directory  bool `short:"d"`
 	LongFormat bool `short:"l"`
-
 	Positional struct {
 		Path string `positional-arg-name:"<path>"`
 	} `positional-args:"yes" required:"yes"`
@@ -53,7 +52,9 @@ func init() {
 			"-d": "List matching entries themselves, not directory contents",
 			"-l": "Use a long listing format",
 		}),
-		Builder: func() flags.Commander { return &cmdLs{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdLs{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_mkdir.go

@@ -30,16 +30,15 @@ The mkdir command creates the specified directory.
 `
 
 type cmdMkdir struct {
-	clientMixin
+	client *client.Client
 
 	MakeParents bool   `short:"p"`
 	Permissions string `short:"m"`
 	UserID      *int   `long:"uid"`
 	User        string `long:"user"`
 	GroupID     *int   `long:"gid"`
 	Group       string `long:"group"`
-
-	Positional struct {
+	Positional  struct {
 		Path string `positional-arg-name:"<path>"`
 	} `positional-args:"yes" required:"yes"`
 }
@@ -49,7 +48,6 @@ func init() {
 		Name:        "mkdir",
 		Summary:     cmdMkdirSummary,
 		Description: cmdMkdirDescription,
-		Builder:     func() flags.Commander { return &cmdMkdir{} },
 		ArgsHelp: map[string]string{
 			"-p":      "Create parent directories as needed",
 			"-m":      "Set permissions (e.g. 0644)",
@@ -58,6 +56,9 @@ func init() {
 			"--gid":   "Use specified group ID",
 			"--group": "Use specified group name",
 		},
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdMkdir{client: opts.Client}
+		},
 	})
 }
 

internals/cli/cmd_plan.go

@@ -27,15 +27,17 @@ format. Layers are combined according to the override rules defined in them.
 `
 
 type cmdPlan struct {
-	clientMixin
+	client *client.Client
 }
 
 func init() {
 	AddCommand(&CmdInfo{
 		Name:        "plan",
 		Summary:     cmdPlanSummary,
 		Description: cmdPlanDescription,
-		Builder:     func() flags.Commander { return &cmdPlan{} },
+		New: func(opts *CmdOptions) flags.Commander {
+			return &cmdPlan{client: opts.Client}
+		},
 	})
 }