install yarn in nginx

                                    pm2 start yarn --name "nextjs" --interpreter bash -- start
pm2 show nextjs

                                    {
  "name": "nextjs-example",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "dev": "node server.js",
    "build": "next build",
    "start": "next start -p 8000",
    "test": "NODE_ENV=test jest",
    "test:watch": "NODE_ENV=test jest --watch",
    "test:coverage": "NODE_ENV=test jest --coverage",
    "test:cypress": "NODE_ENV=test cypress open",
    "lint": "eslint .",
    "lint:watch": "esw . --watch --cache",
    "lint:watchAll": "esw . --watch",
    "circleci:run": "circleci local execute --job $JOB"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/willandskill/nextjs-example.git"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/willandskill/nextjs-example/issues"
  },
  "homepage": "https://github.com/willandskill/nextjs-example#readme",
  "dependencies": {
    ...
  },
  "devDependencies": {
    ...
  }
}

                                    # /etc/nginx/sites-available/nextjs-example.willandskill.eu

server {
    server_name nextjs-example.willandskill.eu;
    access_log /opt/nextjs/logs/access.log;
    error_log /opt/nextjs/logs/error.log error;

    location /_next/ {
        alias /opt/nextjs/project/.next/;
        expires 30d;
        access_log on;
    }

    location / {
        # reverse proxy for next server
        proxy_pass http://localhost:8000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;

        # we need to remove this 404 handling
        # because next's _next folder and own handling
        # try_files $uri $uri/ =404;
    }
}