Awesome

go-lark

go-lark is an easy-to-use SDK for Feishu and Lark Open Platform, which implements messaging APIs, with full-fledged supports on building Chat Bot and Notification Bot.

It is widely used and tested by ~650 ByteDance in-house developers with over 3k Go packages.

Features

Notification bot & chat bot supported
Send messages (Group, Private, Rich Text, and Card)
Quick to build message with MsgBuffer
Easy to create incoming message hook
Encryption and token verification supported
Middleware support for Gin & Hertz web framework
Highly extensible
Documentation & tests

Installation

go get github.com/go-lark/lark

Quick Start

Prerequisite

There are two types of bot that is supported by go-lark. We need to create a bot manually.

Chat Bot:

Feishu: create from Feishu Open Platform.
Lark: create from Lark Developer.
App ID and App Secret are required to init a ChatBot.

Notification Bot:

Create from group chat.
Web Hook URL is required.

Sending Message

Chat Bot:

import "github.com/go-lark/lark"

func main() {
    bot := lark.NewChatBot("<App ID>", "<App Secret>")
    bot.StartHeartbeat()
    bot.PostText("hello, world", lark.WithEmail("someone@example.com"))
}

Notification Bot:

import "github.com/go-lark/lark"

func main() {
    bot := lark.NewNotificationBot("<WEB HOOK URL>")
    bot.PostNotificationV2(lark.NewMsgBuffer(lark.MsgText).Text("hello, wolrd").Build())
}

Feishu/Lark API offers more features, please refers to Usage for further documentation.

Limits

go-lark is tested on Feishu endpoints, which literally compats Lark endpoints, because Feishu and Lark basically shares the same API specification. We do not guarantee all of the APIs work well with Lark, until we have tested it on Lark.
go-lark only supports Custom App. Marketplace App is not supported yet.
go-lark implements messaging, group chat, and bot API, other APIs such as Lark Doc, Calendar and so on are not supported.

Switch to Lark Endpoints

The default API endpoints are for Feishu, in order to switch to Lark, we should use SetDomain:

bot := lark.NewChatBot("<App ID>", "<App Secret>")
bot.SetDomain(lark.DomainLark)

Usage

Auth

Auto-renewable authentication:

// initialize a chat bot with appID and appSecret
bot := lark.NewChatBot(appID, appSecret)
// Renew access token periodically
bot.StartHeartbeat()
// Stop renewal
bot.StopHeartbeat()

Single-pass authentication:

bot := lark.NewChatBot(appID, appSecret)
resp, err := bot.GetTenantAccessTokenInternal(true)
// and we can now access the token value with `bot.TenantAccessToken()`

Example: examples/auth

Messaging

For Chat Bot, we can send simple messages with the following method:

PostText
PostTextMention
PostTextMentionAll
PostImage
PostShareChatCard
ReplyMessage
AddReaction
DeleteReaction

Basic message examples: examples/basic-message

To build rich messages, we may use Message Buffer (or simply MsgBuffer), which builds message conveniently with chaining methods.

Examples

Apart from the general auth and messaging chapter, there are comprehensive examples for almost all APIs. Here is a collection of ready-to-run examples for each part of go-lark:

Message Buffer

We can build message body with MsgBuffer and send with PostMessage, which supports the following message types:

MsgText: Text
MsgPost: Rich Text
MsgInteractive: Interactive Card
MsgShareCard: Group Share Card
MsgShareUser: User Share Card
MsgImage: Image
MsgFile: File
MsgAudio: Audio
MsgMedia: Media
MsgSticker: Sticker

MsgBuffer provides binding functions and content functions.

Binding functions:

Function	Usage	Comment
BindChatID	Bind a chat ID	Either `OpenID`, `UserID`, `Email`, `ChatID` or `UnionID` should be present
BindOpenID	Bind a user open ID
BindUserID	Bind a user ID
BindUnionID	Bind a union ID
BindEmail	Bind a user email
BindReply	Bind a reply ID	Required when reply a message

Content functions pair with message content types. If it mismatched, it would not have sent successfully. Content functions:

Function	Message Type	Usage	Comment
Text	`MsgText`	Append plain text	May build with `TextBuilder`
Post	`MsgPost`	Append rich text	May build with `PostBuilder`
Card	`MsgInteractive`	Append interactive card	May build with `CardBuilder`
ShareChat	`MsgShareCard`	Append group share card
ShareUser	`MsgShareUser`	Append user share card
Image	`MsgImage`	Append image	Required to upload to Lark server in advance
File	`MsgFile`	Append file	Required to upload to Lark server in advance
Audio	`MsgAudio`	Append audio	Required to upload to Lark server in advance
Media	`MsgMedia`	Append media	Required to upload to Lark server in advance
Sticker	`MsgSticker`	Append sticker	Required to upload to Lark server in advance

Error Handling

Each go-lark API function returns response and err. err is the error from HTTP client, when it was not nil, HTTP might have gone wrong.

While response is HTTP response from Lark API server, in which Code and OK represent whether it succeeds. The meaning of Code is defined here.

Event

Lark provides a number of events and they are in two different schema (1.0/2.0). go-lark now only implements a few of them, which are needed for interacting between bot and Lark server:

URL Challenge
Receiving Messages

We recommend HTTP middlewares to handle these events.

Middlewares

We have already implemented HTTP middlewares to support event handling:

Example: examples/gin-middleware examples/hertz-middleware

URL Challenge

r := gin.Default()
middleware := larkgin.NewLarkMiddleware()
middleware.BindURLPrefix("/handle") // supposed URL is http://your.domain.com/handle
r.Use(middleware.LarkChallengeHandler())

Event V2

Lark has provided event v2 and it applied automatically to newly created bots.

r := gin.Default()
middleware := larkgin.NewLarkMiddleware()
r.Use(middleware.LarkEventHandler())

Get the event (e.g. Message):

r.POST("/", func(c *gin.Context) {
    if evt, ok := middleware.GetEvent(c); ok { // => GetEvent instead of GetMessage
        if evt.Header.EventType == lark.EventTypeMessageReceived {
            if msg, err := evt.GetMessageReceived(); err == nil {
                fmt.Println(msg.Message.Content)
            }
        }
    }
})

Card Callback

We may also setup callback for card actions (e.g. button). The URL challenge part is the same.

We may use LarkCardHandler to handle the actions:

r.Use(middleware.LarkCardHandler())
r.POST("/callback", func(c *gin.Context) {
    if card, ok := middleware.GetCardCallback(c); ok {
    }
})

Receiving Message (Event V1)

For older bots, please use v1:

r := gin.Default()
middleware := larkgin.NewLarkMiddleware()
middleware.BindURLPrefix("/handle") // supposed URL is http://your.domain.com/handle
r.POST("/handle", func(c *gin.Context) {
    if msg, ok := middleware.GetMessage(c); ok && msg != nil {
        text := msg.Event.Text
        // your awesome logic
    }
})

Security & Encryption

Lark Open Platform offers AES encryption and token verification to ensure security for events.

AES Encryption: when switch on, all traffic will be encrypted with AES.
Token Verification: simple token verification for incoming messages.

We recommend you to enable token verification. If HTTPS is not available on your host, then enable AES encryption.

middleware.WithTokenVerfication("<verification-token>")
middleware.WithEncryption("<encryption-key>")

Debugging

Lark does not provide messaging API debugger officially. Thus, we have to debug with real Lark conversation. We recommend ngrok to debug events.

And we add PostEvent to simulate message sending to make it even easier. PostEvent can also be used to redirect events, which acts like a reverse proxy.

Development

Test

Dotenv Setup

go-lark uses godotenv test locally. You may have to create a .env file in repo directory, which contains environmental variables:
```
LARK_APP_ID
LARK_APP_SECRET
LARK_USER_EMAIL
LARK_USER_ID
LARK_UNION_ID
LARK_OPEN_ID
LARK_CHAT_ID
LARK_WEBHOOK_V2
LARK_WEBHOOK_V2_SIGNED
```
LARK_APP_ID and LARK_APP_SECRET are mandatory. Others are required only by specific API tests.

Run Test

GO_LARK_TEST_MODE=local ./scripts/test.sh

Extensions

go-lark's dev utilities (authentication, HTTP handling, and etc.) are capable for easily implementing most of APIs provided by Lark Open Platform. And we may use that as an extension for go-lark.

Here is an example that implementing a Lark Doc API with go-lark:

package lark

import "github.com/go-lark/lark"

const copyFileAPIPattern = "/open-apis/drive/explorer/v2/file/copy/files/%s"

// CopyFileResponse .
type CopyFileResponse struct {
	lark.BaseResponse

	Data CopyFileData `json:"data"`
}

// CopyFileData .
type CopyFileData struct {
	FolderToken string `json:"folderToken"`
	Revision    int64  `json:"revision"`
	Token       string `json:"token"`
	Type        string `json:"type"`
	URL         string `json:"url"`
}

// CopyFile implementation
func CopyFile(bot *lark.Bot, fileToken, dstFolderToken, dstName string) (*CopyFileResponse, error) {
	var respData model.CopyFileResponse
	err := bot.PostAPIRequest(
		"CopyFile",
		fmt.Sprintf(copyFileAPIPattern, fileToken),
		true,
		map[string]interface{}{
			"type":             "doc",
			"dstFolderToken":   dstFolderToken,
			"dstName":          dstName,
			"permissionNeeded": true,
			"CommentNeeded":    false,
		},
		&respData,
	)
	return &respData, err
}

FAQ

I got 99991401 when sending messages
- remove IP Whitelist from dashboard
My bot failed sending messages
1. check authentication.
2. not invite to the group.
3. API permission not applied.
Does go-lark support interactive message card?
- Yes, use a CardBuilder.

Contributing

If you think you've found a bug with go-lark, please file an issue.
Pull Request is welcomed.