Plugin

tip

When we need to do some extensions to Answer's functionality, for example, OAuth login, we design a way to use plugins to implement these functions.

Introduction

Official Plugins

You can find a list of officially supported plugins for Answer here.

Plugin Type

We classify plugins into different types. Different types of plugins have different functions. Plugins of the same type have the same effect, but are implemented differently.

• Connector: The Connector plugin helps us to implement third-party login functionality. e.g. GitHub OAuth Login
• Storage: The Storage plugin helps us to upload files to third-party storage. (preview)
• Cache: Support for using different caching middleware. e.g. Redis (preview)
• Filter: Filter out illegal questions or answers. (coming soon)
• Render: Parsers for different content formats. (coming soon)
• Finder: Support for using search engines to speed up the search for question answers. (coming soon)

Build

Answer binary supports packaging different required plugins into the binary.

Prerequisites

• Original Answer binary
• Golang >=1.18

Command

tip

We use the build command provided with the Answer binary to rebuild a version of Answer with the plugin.

For example, let's see how to build an Answer binary that includes the github third-party login plugin

# answer build --with [plugin@plugin_version=[replacement]] --output [file]
$ ./answer build --with github.com/answerdev/plugins/connector/github

# build a new answer with github login plugin then output to ./new_answer.
$ ./answer build --with github.com/answerdev/plugins/connector/[email protected] --output ./new_answer

# with multiple plugins
$ ./answer build \
--with github.com/answerdev/plugins/connector/github \
--with github.com/answerdev/plugins/connector/google

# with local plugins
$ ./answer build --with github.com/answerdev/plugins/connector/[email protected]=/my-local-space

# cross compilation. Build a linux-amd64 binary in macos
$ CGO_ENABLED=0 GOOS=linux GOARCH=amd64 ./answer build --with github.com/answerdev/plugins/connector/github

tip

You can use the plugin command to list the current binary containing plugins.

$ ./new_answer plugin

# output
# github connector[0.0.1] made by answerdev
# google connector[0.0.1] made by answerdev

Third-party plugin

tip

We recommend the use of official plugins, if you want to use third-party plugins, refer to the following.

• If the third-party plugin is publicly available, you can build with it like official plugins.
• If the third-party plugin is private, you need to download it then build with.

Use

The answer with the plug-in version is used in the same way as before. You can find the plugin's configuration in the admin page.

Upgrade

You just need to recompile and use the latest version of the plugin.

Develop

tip

Viewing the official plugin code will make you to quickly understand and learn plugin development.

Backend Development

Implement the base

The Base interface contains basic information about the plugin and is used to display.

// Info presents the plugin information
type Info struct {
    Name        Translator
    SlugName    string
    Description Translator
    Author      string
    Version     string
    Link        string
}

// Base is the base plugin
type Base interface {
    // Info returns the plugin information
    Info() Info
}

caution

The SlugName of the plugin must be unique. Two plugins with the same SlugName will panic when registering.

Implement the function interface

note

Different plugin types require different interfaces of implementation.

For example, following is the Connector plugin interface.

type Connector interface {
    Base
    
    // ConnectorLogoSVG presents the logo in svg format
    ConnectorLogoSVG() string
    
    // ConnectorName presents the name of the connector
    // e.g. Facebook, Twitter, Instagram
    ConnectorName() Translator
    
    // ConnectorSlugName presents the slug name of the connector
    // Please use lowercase and hyphen as the separator
    // e.g. facebook, twitter, instagram
    ConnectorSlugName() string
    
    // ConnectorSender presents the sender of the connector
    // It handles the start endpoint of the connector
    // receiverURL is the whole URL of the receiver
    ConnectorSender(ctx *GinContext, receiverURL string) (redirectURL string)
    
    // ConnectorReceiver presents the receiver of the connector
    // It handles the callback endpoint of the connector, and returns the
    ConnectorReceiver(ctx *GinContext, receiverURL string) (userInfo ExternalLoginUserInfo, err error)
}

tip

Translator is a struct for translation. Please refer to the documentation for details.

Implement the configuration interface

For details on the description of each configuration item, please refer to the documentation.

type Config interface {
    Base

    // ConfigFields returns the list of config fields
    ConfigFields() []ConfigField

    // ConfigReceiver receives the config data, it calls when the config is saved or initialized.
    // We recommend to unmarshal the data to a struct, and then use the struct to do something.
    // The config is encoded in JSON format.
    // It depends on the definition of ConfigFields.
    ConfigReceiver(config []byte) error
}

Register initialization function

import "github.com/answerdev/answer/plugin"

func init() {
    plugin.Register(&GitHubConnector{
        Config: &GitHubConnectorConfig{},
    })
}

Debugging tips

tip

During the development and debugging phase, you can use the following tips to avoid repetitive packaging.

1. Use answer source code for development.
2. Write your plugin directly in the plugin directory.
3. Import your plugin in the main function

After that you just need to start the answer project normally and it will contain the plugins you developed.

Contributing

For plugin types that have not been implemented yet, please wait for the official implementation to be completed before contributing. For existing plugin types, you can follow the steps below to contribute the plugin implementation to us.

1. Submit an issue request to ensure that the official is not developing the same plug-in as you.
2. Get confirmation that you can develop your plugin, test it and submit a PR.
3. Wait for the PR merge, the official will include your plugin.

Design & Principle

Since Golang is a static language, there is no friendly plugin mechanism. So instead of a dynamic approach, we use recompilation for deployment.