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
• Node.js >=16.17
• pnpm >=7

Command

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/apache/incubator-answer-plugins/connector-github
# build a new answer with github login plugin then output to ./new_answer.
$ ./answer build --with github.com/apache/incubator-answer-plugins/connector-github@1.0.0 --output ./new_answer
# with multiple plugins
$ ./answer build \
--with github.com/apache/incubator-answer-plugins/connector-github \
--with github.com/apache/incubator-answer-plugins/connector-google
# with local plugins
$ ./answer build --with github.com/apache/incubator-answer-plugins/connector-github@1.0.0=/my-local-space
# cross compilation. Build a linux-amd64 binary in macos
$ CGO_ENABLED=0 GOOS=linux GOARCH=amd64 ./answer build --with github.com/apache/incubator-answer-plugins/connector-github
# specify the answer version using ANSWER_MODULE environment variable
$ ANSWER_MODULE=github.com/apache/incubator-answer@v1.2.0-RC1 ./answer build --with github.com/apache/incubator-answer-plugins/connector-github

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

Build docker image with plugin from answer base image

You can follow the steps above to build the binary with the plugin first, and then build a docker image that contains the binary. Of course, you can also build directly on top of the original image.

```dockerfile title=”Dockerfile” FROM apache/answer as answer-builder

FROM golang:1.19-alpine AS golang-builder

COPY —from=answer-builder /usr/bin/answer /usr/bin/answer

RUN apk —no-cache add \ build-base git bash nodejs npm go && \ npm install -g pnpm@8.9.2

RUN answer build \ —with github.com/apache/incubator-answer-plugins/connector-basic \ —with github.com/apache/incubator-answer-plugins/storage-s3 \ —with github.com/apache/incubator-answer-plugins/search-elasticsearch \ —output /usr/bin/new_answer

FROM alpine LABEL maintainer=”linkinstar@apache.org”

ARG TIMEZONE ENV TIMEZONE=${TIMEZONE:-“Asia/Shanghai”}

RUN apk update \ && apk —no-cache add \ bash \ ca-certificates \ curl \ dumb-init \ gettext \ openssh \ sqlite \ gnupg \ tzdata \ && ln -sf /usr/share/zoneinfo/${TIMEZONE} /etc/localtime \ && echo “${TIMEZONE}” > /etc/timezone

COPY —from=golang-builder /usr/bin/new_answer /usr/bin/answer COPY —from=answer-builder /data /data COPY —from=answer-builder /entrypoint.sh /entrypoint.sh RUN chmod 755 /entrypoint.sh

VOLUME /data EXPOSE 80 ENTRYPOINT [“/entrypoint.sh”]

> You can update the --with parameter to add more plugins that you need.
```shell
# create a Dockerfile and copy the content above
$ vim Dockerfile
$ docker build -t answer-with-plugin .
$ docker run -d -p 9080:80 -v answer-data:/data --name answer answer-with-plugin

Third-party plugin

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.

Usage

The Answer with the plugin version is used in the same way as before. You can find the plugin’s configuration in the admin page.

Upgrade

Note that if you are upgrading from a non-plugin version to a plugin version, you also need to execute the upgrade command (also considered as an upgrade).

You need build a new Answer binary with the new plugin version, then replace the old Answer binary with the new one. As with normal upgrades, you need to execute different upgrade steps depending on the deployment method. For example, if you are using binary deployment, you need to execute the upgrade command.

Develop and contributing

Please refer to the documentation for details.

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. Please refer to the blog for details.