go-lark

简体中文

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 ~450 ByteDance in-house developers with over 1.5k 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 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.PostNotification("title", "text")
}

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 bot and messaging API, other APIs such as Lark Doc, Calendar and so so are not supported.
go-lark implements API in v3/v4 version* (official documents may also mention im/v1 version) and event with Schema 1.0.

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

Messaging

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

PostText
PostTextMention
PostTextMentionAll
PostImage
PostShareChatCard

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
MsgImage: Image
MsgShareCard: Group Share Card
MsgInteractive: Interactive Card

MsgBuffer provides binding functions and content functions.

Binding functions:

Function	Usage	Comment
BindChatID	Bind a chat ID	Either `OpenID`, `UserID`, `Email` or `ChatID` should be present
BindOpenID	Bind a user open ID
BindUserID	Bind a user ID
BindEmail	Bind a user email
BindReply	Bind a reply ID	Required when reply other 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`
Image	`MsgImage`	Append image	Required to upload to Lark server in advance
ShareChat	`MsgShareCard`	Append group share card
Card	`MsgInteractive`	Append interactive card	May build with `CardBuilder`, see Declarative card builder

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 two of them in schema 1.0, which are needed for interacting between bot and Lark server:

URL Challenge
Receiving Messages

We recommend Gin middleware to handle these events.

Gin Middleware

Example: examples/gin-middleware

URL Challenge

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

Receiving Message

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>")

Lark does not provide messaging API debugger officially. Thus, we have to debug with real Lark conversation. We add PostEvent to simulate message sending to make it easier. PostEvent can also be used to redirect message, which acts like a reverse proxy.

Example: examples/event-forward

Notice: PostEvent does not support AES encryption at the moment.

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
}

Compatibility

go-lark is based on Lark API v3 and v4. The compatibility of each API depends on actual implementation. Compatibility table:

API scope	Compatibility	Migration
auth	N/A	Lark does not offer v4
messaging	v4 only
interactive card	v4 only
bot	N/A	Lark does not offer v4
group	partial v3 & v4	WIP

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?
- It can send but no card builder provided. You may need to build it manually and send with go-lark.

Contributing

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

machinly/lark