【ラズパイでもDocker！】Docker Alpineコンテナ上のNode.jsネイティブアプリからラズパイのGPIOを操作する方法

            $ docker pull arm32v7/node:alpine
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
arm32v7/node        alpine              30bb03f6ec2e        6 months ago        96.6MB
armhf/alpine        latest              15ed6d4bf10d        2 years ago         3.6MB
        

            $ docker run -it \
    --rm \
    -v /sys:/sys \
    arm32v7/node:alpine /bin/sh
        

            $ apk add --update python make g++
        

            $ mkdir /usr/local/app && cd /usr/local/app
#👇新規のpackage.jsonを発行
$ npm init -y
Wrote to /usr/local/app/package.json:
{
  "name": "app",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

#👇index.jsがアプリのエントリーポイント
$ touch index.js
$ ls
index.js package.json
        

            $ npm i onoff
> epoll@4.0.0 install /usr/local/app/node_modules/epoll
> node-gyp rebuild

make: Entering directory '/usr/local/app/node_modules/epoll/build'
  CXX(target) Release/obj.target/epoll/app/epoll.o
  SOLINK_MODULE(target) Release/obj.target/epoll.node
  COPY Release/epoll.node
make: Leaving directory '/usr/local/app/node_modules/epoll/build'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN src@1.0.0 No description
npm WARN src@1.0.0 No repository field.

+ onoff@6.0.0
added 6 packages from 12 contributors and audited 6 packages in 26.364s
found 0 vulnerabilities
        

            const { Gpio } = require('onoff');

// GPIO2を出力設定で利用
const ledOut = new Gpio('2', 'out');

// LEDの状態(false=消灯)
let isLedOn = false;

// 一定時間間隔でループ処理
setInterval(() => {
    ledOut.writeSync( isLedOn ? 0 : 1 ); // 1の書き込みで点灯・0で消灯
    isLedOn = !isLedOn; // 状態を反転
}, 500); // 0.5秒
        

            $ node index.js
#...ずっとチカチカ
        

            $ docker run -it \
    --rm \
    --device /dev/gpiomem \
    arm32v7/node:alpine /bin/sh
        

            $ node index.js
internal/fs/utils.js:220
    throw err;
    ^

Error: EROFS: read-only file system, open '/sys/class/gpio/export'
    at Object.openSync (fs.js:440:3)
    at Object.writeFileSync (fs.js:1281:35)
    at exportGpio (/usr/local/app/node_modules/onoff/onoff.js:18:8)
    at new Gpio (/usr/local/app/node_modules/onoff/onoff.js:172:36)
    at Object.<anonymous> (/usr/local/app/index.js:4:16)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1103:10)
    at Module.load (internal/modules/cjs/loader.js:914:32)
    at Function.Module._load (internal/modules/cjs/loader.js:822:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1143:12) {
  errno: -30,
  syscall: 'open',
  code: 'EROFS',
  path: '/sys/class/gpio/export'
}
        

            FROM arm32v7/node:alpine
RUN apk update && \
    apk upgrade && \
    apk add --no-cache python make g++ alpine-sdk unzip bash

RUN wget https://github.com/joan2937/pigpio/archive/master.zip && \
    unzip master.zip && \
    cd pigpio-master && \
    sed -i 's,ldconfig,,' Makefile && \
    make && \
    make install

WORKDIR /usr/local/app
COPY package.json /usr/local/app
COPY index.js /usr/local/app
RUN npm install
        

            $ docker build . -t taconocat/pigpio
        

            $ docker run -it \
    --rm \
    --privileged \
    taconocat/pigpio /bin/bash
        

            const Gpio = require('pigpio').Gpio;

const led = new Gpio(2, {mode: Gpio.OUTPUT});

let isLedOn = false;

// 一定時間間隔でループ処理
setInterval(() => {
    if (isLedOn) {
        led.digitalWrite(1);
    } else {
        // led.off();
        led.digitalWrite(0);
    }
    isLedOn = !isLedOn; // 状態を反転
}, 1000); // 0.5秒
        

            {
  "name": "pigpio-master",
  "version": "1.0.0",
  "description": "pigpio is a C library for the Raspberry which allows control of the General Purpose Input Outputs (GPIO).",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "pigpio": "^3.2.1"
  }
}
        

            $ docker run -it \
    --rm \
    --cap-add SYS_ADMIN \
    --device /dev/gpiomem \
    taconocat/pigpio /bin/bash
        

            $ node index.js
2020-05-07 16:13:07 initCheckPermitted:
+---------------------------------------------------------+
|Sorry, you don't have permission to run this program.    |
|Try running as root, e.g. precede the command with sudo. |
+---------------------------------------------------------+

/usr/local/app/pigpio-master/node_modules/pigpio/pigpio.js:29
    pigpio.gpioInitialise();
           ^

Error: pigpio error -1 in gpioInitialise
    at initializePigpio (/usr/local/app/pigpio-master/node_modules/pigpio/pigpio.js:29:12)
    at new Gpio (/usr/local/app/pigpio-master/node_modules/pigpio/pigpio.js:133:5)
    at Object.<anonymous> (/usr/local/app/pigpio-master/index.js:3:13)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
    at startup (internal/bootstrap/node.js:283:19)
        

            FROM arm32v7/node:alpine
RUN apk update && \
    apk upgrade && \
    apk add --no-cache --virtual build-deps python make g++ alpine-sdk unzip

RUN cd /tmp && \
    wget https://github.com/joan2937/pigpio/archive/master.zip && \
    unzip -qq master.zip && \
    cd pigpio-master && \
    sed -i 's,ldconfig,,' Makefile && \
    make && \
    make install && \
    rm -rf /tmp/*

WORKDIR /usr/local/app
COPY package.json /usr/local/app
COPY index.js /usr/local/app
RUN npm install &&　\
    apk del build-deps

CMD ["node", "index.js"]
        

            #デタッチモードで起動
$ docker run -d --privileged taconocat/pigpio
#起動デーモンに登録し常駐化
$ docker update --restart=always taconocat/pigpio