package module
v0.11.0 Latest Latest

This package is not in the latest version of its module.

Go to latest
Published: Jul 26, 2020 License: BSD-3-Clause Imports: 21 Imported by: 25


Joe Bot :robot:

A general-purpose bot library inspired by Hubot but written in Go.

Joe is a library used to write chat bots in the Go programming language. It is very much inspired by the awesome Hubot framework developed by the folks at Github and brings its power to people who want to implement chat bots using Go.

Getting Started

Joe is a software library that is packaged as Go module. You can get it via:

go get

Example usage

You can find all code examples, more explanation and complete recipes at

Each bot consists of a chat Adapter (e.g. to integrate with Slack), a Memory implementation to remember key-value data (e.g. using Redis) and a Brain which routes new messages or custom events (e.g. receiving an HTTP call) to the corresponding registered handler functions.

By default joe.New(…) uses the CLI adapter which makes the bot read messages from stdin and respond on stdout. Additionally the bot will store key value data in-memory which means it will forget anything you told it when it is restarted. This default setup is useful for local development without any dependencies but you will quickly want to add other Modules to extend the bots capabilities.

The following example connects the Bot with a Slack workspace and stores key-value data in Redis. To allow the message handlers to access the memory we define them as functions on a custom ExampleBottype which embeds the joe.Bot.

package main

import (


type ExampleBot struct {

func main() {
	b := &ExampleBot{
		Bot: joe.New("example",

	b.Respond("remember (.+) is (.+)", b.Remember)
	b.Respond("what is (.+)", b.WhatIs)

	err := b.Run()
	if err != nil {

func (b *ExampleBot) Remember(msg joe.Message) error {
	key, value := msg.Matches[0], msg.Matches[1]
	msg.Respond("OK, I'll remember %s is %s", key, value)
	return b.Store.Set(key, value)

func (b *ExampleBot) WhatIs(msg joe.Message) error {
	key := msg.Matches[0]
	var value string
	ok, err := b.Store.Get(key, &value)
	if err != nil {
		return fmt.Errorf("failed to retrieve key %q from brain: %w", key, err)

	if ok {
		msg.Respond("%s is %s", key, value)
	} else {
		msg.Respond("I do not remember %q", key)

	return nil

Available modules

Joe ships with no third-party modules such as Redis integration to avoid pulling in more dependencies than you actually require. There are however already some modules that you can use directly to extend the functionality of your bot without writing too much code yourself.

If you have written a module and want to share it, please add it to this list and open a pull request.

Chat Adapters

Memory Modules

Other Modules

Built With

  • zap - Blazing fast, structured, leveled logging in Go
  • multierr - Package multierr allows combining one or more errors together
  • testify - A simple unit test library


Please read for details on our code of conduct and on the process for submitting pull requests to this repository.



All significant (e.g. breaking) changes are documented in the

After the v1.0 release we plan to use SemVer for versioning. For the versions available, see the tags on this repository.


  • Friedrich Große - Initial work - fgrosse

See also the list of contributors who participated in this project.


This project is licensed under the BSD-3-Clause License - see the LICENSE file for details.


  • Hubot and its great community for the inspiration
  • embedmd for a cool tool to embed source code in markdown files



Package joe contains a general purpose bot library inspired by Hubot.



View Source
const ErrNotAllowed = Error("not allowed")

ErrNotAllowed is returned if the user is not allowed access to a specific scope.

View Source
const ErrNotImplemented = Error("not implemented")

ErrNotImplemented is returned if the user tries to use a feature that is not implemented on the corresponding components (e.g. the Adapter). For instance, not all Adapter implementations may support emoji reactions and trying to attach a reaction to a message might return this error.


This section is empty.


func FinishEventContent added in v0.10.0

func FinishEventContent(ctx context.Context)

FinishEventContent can be called from within your event handler functions to indicate that the Brain should not execute any other handlers after the calling handler has returned.


type Adapter

type Adapter interface {
	Send(text, channel string) error
	Close() error

An Adapter connects the bot with the chat by enabling it to receive and send messages. Additionally advanced adapters can emit more events than just the ReceiveMessageEvent (e.g. the slack adapter also emits the UserTypingEvent). All adapter events must be setup in the RegisterAt function of the Adapter.

Joe provides a default CLIAdapter implementation which connects the bot with the local shell to receive messages from stdin and print messages to stdout.

type Auth added in v0.7.0

type Auth struct {
	// contains filtered or unexported fields

Auth implements logic to add user authorization checks to your bot.

func NewAuth added in v0.7.0

func NewAuth(logger *zap.Logger, store *Storage) *Auth

NewAuth creates a new Auth instance.

func (*Auth) CheckPermission added in v0.7.0

func (a *Auth) CheckPermission(scope, userID string) error

CheckPermission checks if a user has permissions to access a resource under a given scope. If the user is not permitted access this function returns ErrNotAllowed.

Scopes are interpreted in a hierarchical way where scope A can contain scope B if A is a prefix to B. For example, you can check if a user is allowed to read or write from the "Example" API by checking the "" or "api.example.write" scope. When you grant the scope to a user you can now either decide only to grant the very specific "" scope which means the user will not have write permissions or you can allow people write-only access via "api.example.write".

Alternatively you can also grant any access to the Example API via "api.example" which includes both the read and write scope beneath it. If you choose to, you could also allow even more general access to everything in the api via the "api" scope. The empty scope "" cannot be granted and will thus always return an error in the permission check.

func (*Auth) Grant added in v0.7.0

func (a *Auth) Grant(scope, userID string) (bool, error)

Grant adds a permission scope to the given user. When a scope was granted to a specific user it can be checked later via CheckPermission(…). The returned boolean indicates whether the scope was actually added (i.e. true) or the user already had the granted scope (false).

Note that granting a scope is an idempotent operations so granting the same scope multiple times is a safe operation and will not change the internal permissions that are written to the Memory.

The empty scope cannot be granted and trying to do so will result in an error. If you want to grant access to all scopes you should prefix them with a common scope such as "root." or "api.".

func (*Auth) Revoke added in v0.8.0

func (a *Auth) Revoke(scope, userID string) (bool, error)

Revoke removes a previously granted permission from a user. If the user does not currently have the revoked scope this function returns false and no error.

If you are trying to revoke a permission but the user was previously granted a scope that contains the revoked scope this function returns an error.

func (*Auth) UserPermissions added in v0.9.0

func (a *Auth) UserPermissions(userID string) ([]string, error)

UserPermissions returns all permission scopes for a specific user.

func (*Auth) Users added in v0.9.0

func (a *Auth) Users() ([]string, error)

Users returns a list of user IDs having one or more permission scopes.

type Bot

type Bot struct {
	Name    string
	Adapter Adapter
	Brain   *Brain
	Store   *Storage
	Auth    *Auth
	Logger  *zap.Logger
	// contains filtered or unexported fields

A Bot represents an event based chat bot. For the most simple usage you can use the Bot.Respond(…) function to make the bot execute a function when it receives a message that matches a given pattern.

More advanced usage includes persisting memory or emitting your own events using the Brain of the robot.

func New

func New(name string, modules ...Module) *Bot

New creates a new Bot and initializes it with the given Modules and Options. By default the Bot will use an in-memory Storage and a CLI adapter that reads messages from stdin and writes to stdout.

The modules can be used to change the Memory or Adapter or register other new functionality. Additionally you can pass Options which allow setting some simple configuration such as the event handler timeouts or injecting a different context. All Options are available as functions in this package that start with "With…".

If there was an error initializing a Module it is stored and returned on the next call to Bot.Run(). Before you start the bot however you should register your custom event handlers.


b := joe.New("example",

b.Respond("ping", b.Pong)

err := b.Run()

func (*Bot) Respond

func (b *Bot) Respond(msg string, fun func(Message) error)

Respond registers an event handler that listens for the ReceiveMessageEvent and executes the given function only if the message text matches the given message. The message will be matched against the msg string as regular expression that must match the entire message in a case insensitive way.

You can use sub matches in the msg which will be passed to the function via Message.Matches.

If you need complete control over the regular expression, e.g. because you want the patter to match only a substring of the message but not all of it, you can use Bot.RespondRegex(…). For even more control you can also directly use Brain.RegisterHandler(…) with a function that accepts ReceiveMessageEvent instances.

If multiple matching patterns are registered, only the first registered handler is executed.

func (*Bot) RespondRegex

func (b *Bot) RespondRegex(expr string, fun func(Message) error)

RespondRegex is like Bot.Respond(…) but gives a little more control over the regular expression. However, also with this function messages are matched in a case insensitive way.

func (*Bot) Run

func (b *Bot) Run() error

Run starts the bot and runs its event handler loop until the bots context is canceled (by default via SIGINT, SIGQUIT or SIGTERM). If there was an an error when setting up the Bot via New() or when registering the event handlers it will be returned immediately.

func (*Bot) Say

func (b *Bot) Say(channel, msg string, args ...interface{})

Say is a helper function to makes the Bot output the message via its Adapter (e.g. to the CLI or to Slack). If there is at least one vararg the msg and args are formatted using fmt.Sprintf.

type Brain

type Brain struct {
	// contains filtered or unexported fields

The Brain contains the core logic of a Bot by implementing an event handling system that dispatches events to all registered event handlers.

func NewBrain

func NewBrain(logger *zap.Logger) *Brain

NewBrain creates a new robot Brain. If the passed logger is nil it will fallback to the zap.NewNop() logger.

func (*Brain) Emit

func (b *Brain) Emit(event interface{}, callbacks ...func(Event))

Emit sends the first argument as event to the brain from where it is dispatched to all registered handlers. The events are dispatched asynchronously but in the same order in which they are send to this function. Emit does not block until the event is delivered to the registered event handlers. If you want to wait until all handlers have processed the event you can pass one or more callback functions that will be executed when all handlers finished execution of this event.

func (*Brain) HandleEvents

func (b *Brain) HandleEvents()

HandleEvents starts the event handling loop of the Brain. This function blocks until Brain.Shutdown() is called and returned.

func (*Brain) RegisterHandler

func (b *Brain) RegisterHandler(fun interface{})

RegisterHandler registers a function to be executed when a specific event is fired. The function signature must comply with the following rules or the bot that uses this Brain will return an error on its next Bot.Run() call:

Allowed function signatures:

// AnyType can be any scalar, struct or interface type as long as it is not
// a pointer.

// You can optionally accept a context as the first argument. The context
// is used to signal handler timeouts or when the bot is shutting down.
func(context.Context, AnyType)

// You can optionally return a single error value. Returning any other type
// or returning more than one value is not possible. If the handler
// returns an error it will be logged.
func(AnyType) error

// Event handlers can also accept an interface in which case they will be
// be called for all events which implement the interface. Consequently,
// you can register a function which accepts the empty interface which will
// will receive all emitted events. Such event handlers can optionally also
// accept a context and/or return an error like other handlers.
func(context.Context, interface{}) error

The event, that will be dispatched to the passed handler function, corresponds directly to the accepted function argument. For instance if you want to emit and receive a custom event you can implement it like this:

type CustomEvent struct {}

b := NewBrain(nil)
b.RegisterHandler(func(evt CustomEvent) {

If multiple handlers are registered for the same event type, then they are all executed in the order in which they have been registered.

You should register all handlers before you start the bot via Bot.Run(…). While registering handlers later is also possible, any registration errors will silently be ignored if you register an invalid handler when the bot is already running.

func (*Brain) Shutdown added in v0.2.0

func (b *Brain) Shutdown(ctx context.Context)

Shutdown stops the event handler loop of the Brain and waits until all pending events have been processed. After the brain is shutdown, it will no longer accept new events. The passed context can be used to stop waiting for any pending events or handlers and instead exit immediately (e.g. after a timeout or a second SIGTERM).

type CLIAdapter

type CLIAdapter struct {
	Prefix string
	Input  io.ReadCloser
	Output io.Writer
	Logger *zap.Logger
	Author string // used to set the author of the messages, defaults to os.Getenv("USER)
	// contains filtered or unexported fields

The CLIAdapter is the default Adapter implementation that the bot uses if no other adapter was configured. It emits a ReceiveMessageEvent for each line it receives from stdin and prints all sent messages to stdout.

The CLIAdapter does not set the Message.Data field.

func NewCLIAdapter

func NewCLIAdapter(name string, logger *zap.Logger) *CLIAdapter

NewCLIAdapter creates a new CLIAdapter. The caller must call Close to make the CLIAdapter stop reading messages and emitting events.

func (*CLIAdapter) Close

func (a *CLIAdapter) Close() error

Close makes the CLIAdapter stop emitting any new events or printing any output. Calling this function more than once will result in an error.

func (*CLIAdapter) React added in v0.9.0

func (a *CLIAdapter) React(r reactions.Reaction, _ Message) error

React implements the optional ReactionAwareAdapter interface by simply printing the given reaction as UTF8 emoji to the CLI.

func (*CLIAdapter) RegisterAt added in v0.2.0

func (a *CLIAdapter) RegisterAt(brain *Brain)

RegisterAt starts the CLIAdapter by reading messages from stdin and emitting a ReceiveMessageEvent for each of them. Additionally the adapter hooks into the InitEvent to print a nice prefix to stdout to show to the user it is ready to accept input.

func (*CLIAdapter) Send

func (a *CLIAdapter) Send(text, channel string) error

Send implements the Adapter interface by sending the given text to stdout. The channel argument is required by the Adapter interface but is otherwise ignored.

type Config

type Config struct {
	Context        context.Context
	Name           string
	HandlerTimeout time.Duration
	// contains filtered or unexported fields

Config is the configuration of a Bot that can be used or changed during setup in a Module. Some configuration settings such as the Logger are read only can only be accessed via the corresponding getter function of the Config.

func NewConfig added in v0.6.0

func NewConfig(logger *zap.Logger, brain *Brain, store *Storage, adapter Adapter) Config

NewConfig creates a new Config that is used to setup the underlying components of a Bot. For the typical use case you do not have to create a Config yourself but rather configure a Bot by passing the corresponding Modules to joe.New(…).

func (*Config) EventEmitter

func (c *Config) EventEmitter() EventEmitter

EventEmitter returns the EventEmitter that can be used to send events to the Bot and other modules.

func (*Config) Logger

func (c *Config) Logger(name string) *zap.Logger

Logger returns a new named logger.

func (*Config) RegisterHandler

func (c *Config) RegisterHandler(fun interface{})

RegisterHandler can be used to register an event handler in a Module.

func (*Config) SetAdapter

func (c *Config) SetAdapter(a Adapter)

SetAdapter can be used to change the Adapter implementation of the Bot.

func (*Config) SetMemory

func (c *Config) SetMemory(mem Memory)

SetMemory can be used to change the Memory implementation of the bot.

func (*Config) SetMemoryEncoder added in v0.8.0

func (c *Config) SetMemoryEncoder(enc MemoryEncoder)

SetMemoryEncoder can be used to change the MemoryEncoder implementation of the bot.

type Error added in v0.7.0

type Error string

Error is the error type used by Joe. This allows joe errors to be defined as constants following

func (Error) Error added in v0.7.0

func (err Error) Error() string

Error implements the "error" interface of the standard library.

type Event

type Event struct {
	Data       interface{}
	Callbacks  []func(Event)
	AbortEarly bool

An Event represents a concrete event type and optional callbacks that are triggered when the event was processed by all registered handlers.

type EventEmitter

type EventEmitter interface {
	Emit(event interface{}, callbacks ...func(Event))

The EventEmitter can be used by a Module by calling Config.EventEmitter(). Events are emitted asynchronously so every call to Emit is non-blocking.

type InitEvent

type InitEvent struct{}

The InitEvent is the first event that is handled by the Brain after the Bot is started via Bot.Run().

type Memory

type Memory interface {
	Set(key string, value []byte) error
	Get(key string) ([]byte, bool, error)
	Delete(key string) (bool, error)
	Keys() ([]string, error)
	Close() error

The Memory interface allows the bot to persist data as key-value pairs. The default implementation of the Memory is to store all keys and values in a map (i.e. in-memory). Other implementations typically offer actual long term persistence into a file or to redis.

type MemoryEncoder added in v0.8.0

type MemoryEncoder interface {
	Encode(value interface{}) ([]byte, error)
	Decode(data []byte, target interface{}) error

A MemoryEncoder is used to encode and decode any values that are stored in the Memory. The default implementation that is used by the Storage uses a JSON encoding.

type Message

type Message struct {
	Context  context.Context
	ID       string // The ID of the message, identifying it at least uniquely within the Channel
	Text     string
	AuthorID string
	Channel  string
	Matches  []string    // contains all sub matches of the regular expression that matched the Text
	Data     interface{} // corresponds to the ReceiveMessageEvent.Data field
	// contains filtered or unexported fields

A Message is automatically created from a ReceiveMessageEvent and then passed to the RespondFunc that was registered via Bot.Respond(…) or Bot.RespondRegex(…) when the message matches the regular expression of the handler.

func (*Message) React added in v0.9.0

func (msg *Message) React(reaction reactions.Reaction) error

React attempts to let the Adapter attach the given reaction to this message. If the adapter does not support this feature this function will return ErrNotImplemented.

func (*Message) Respond

func (msg *Message) Respond(text string, args ...interface{})

Respond is a helper function to directly send a response back to the channel the message originated from. This function ignores any error when sending the response. If you want to handle the error use Message.RespondE instead.

func (*Message) RespondE

func (msg *Message) RespondE(text string, args ...interface{}) error

RespondE is a helper function to directly send a response back to the channel the message originated from. If there was an error it will be returned from this function.

type Module

type Module interface {
	Apply(*Config) error

A Module is an optional Bot extension that can add new capabilities such as a different Memory implementation or Adapter.

func WithContext

func WithContext(ctx context.Context) Module

WithContext is an option to replace the default context of a bot.

func WithHandlerTimeout

func WithHandlerTimeout(timeout time.Duration) Module

WithHandlerTimeout is an option to set a timeout on event handlers functions. By default no timeout is enforced.

func WithLogLevel added in v0.11.0

func WithLogLevel(level zapcore.Level) Module

WithLogLevel is an option to change the default log level of a bot.

func WithLogger added in v0.3.0

func WithLogger(logger *zap.Logger) Module

WithLogger is an option to replace the default logger of a bot.

type ModuleFunc added in v0.4.0

type ModuleFunc func(*Config) error

ModuleFunc is a function implementation of a Module.

func (ModuleFunc) Apply added in v0.4.0

func (f ModuleFunc) Apply(conf *Config) error

Apply implements the Module interface.

type ReactionAwareAdapter added in v0.9.0

type ReactionAwareAdapter interface {
	React(reactions.Reaction, Message) error

ReactionAwareAdapter is an optional interface that Adapters can implement if they support reacting to messages with emojis.

type ReceiveMessageEvent

type ReceiveMessageEvent struct {
	ID       string // The ID of the message, identifying it at least uniquely within the Channel
	Text     string // The message text.
	AuthorID string // A string identifying the author of the message on the adapter.
	Channel  string // The channel over which the message was received.

	// A message may optionally also contain additional information that was
	// received by the Adapter (e.g. with the slack adapter this may be the
	// *slack.MessageEvent. Each Adapter implementation should document if and
	// what information is available here, if any at all.
	Data interface{}

The ReceiveMessageEvent is typically emitted by an Adapter when the Bot sees a new message from the chat.

type ShutdownEvent

type ShutdownEvent struct{}

The ShutdownEvent is the last event that is handled by the Brain before it stops handling any events after the bot context is done.

type Storage added in v0.8.0

type Storage struct {
	// contains filtered or unexported fields

A Storage provides a convenient interface to a Memory implementation. It is responsible for how the actual key value data is encoded and provides concurrent access as well as logging.

The default Storage that is returned by joe.NewStorage() encodes values as JSON and stores them in-memory.

func NewStorage added in v0.8.0

func NewStorage(logger *zap.Logger) *Storage

NewStorage creates a new Storage instance that encodes values as JSON and stores them in-memory. You can change the memory and encoding via the provided setters.

func (*Storage) Close added in v0.8.0

func (s *Storage) Close() error

Close closes the Memory that is managed by this Storage.

func (*Storage) Delete added in v0.8.0

func (s *Storage) Delete(key string) (bool, error)

Delete removes a key and its associated value from the memory. The boolean return value indicates if the key existed or not.

func (*Storage) Get added in v0.8.0

func (s *Storage) Get(key string, value interface{}) (bool, error)

Get retrieves the value under the requested key and decodes it into the passed "value" argument which must be a pointer. The boolean return value indicates if the value actually existed in the Memory and is false if it did not. It is legal to pass <nil> as the value if you only want to check if the given key exists but you do not actually care about the concrete value.

func (*Storage) Keys added in v0.8.0

func (s *Storage) Keys() ([]string, error)

Keys returns all keys known to the Memory.

func (*Storage) Set added in v0.8.0

func (s *Storage) Set(key string, value interface{}) error

Set encodes the given data and stores it in the Memory that is managed by the Storage.

func (*Storage) SetMemory added in v0.8.0

func (s *Storage) SetMemory(m Memory)

SetMemory assigns a different Memory implementation.

func (*Storage) SetMemoryEncoder added in v0.8.0

func (s *Storage) SetMemoryEncoder(enc MemoryEncoder)

SetMemoryEncoder assigns a different MemoryEncoder.

type User

type User struct {
	ID       string
	Name     string
	RealName string

User contains all the information about a user.

type UserTypingEvent

type UserTypingEvent struct {
	User    User
	Channel string

The UserTypingEvent is emitted by the Adapter and indicates that the Bot sees that a user is typing. This event may not be emitted on all Adapter implementations but only when it is actually supported (e.g. on slack).


Path Synopsis
Package joetest implements helpers to implement unit tests for bots.
Package joetest implements helpers to implement unit tests for bots.
Package reactions contains a list of generated reactions that are widely used in different chat applications on the internet.
Package reactions contains a list of generated reactions that are widely used in different chat applications on the internet.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL