vercel.json

{
    "buildCommand": "npm install && npm run build && (npm run update-s || true) && bundle exec jekyll build",
    "outputDirectory": "_site",
    "installCommand": "npm install && bundle install",
    "framework": null,
    "devCommand": "bundle exec jekyll serve --port $PORT",
    "headers": [
        {
            "source": "/api/(.*)",
            "headers": [
                { "key": "Access-Control-Allow-Credentials", "value": "true" },
                { "key": "Access-Control-Allow-Origin", "value": "*" },
                {
                    "key": "Access-Control-Allow-Methods",
                    "value": "GET,OPTIONS,PATCH,DELETE,POST,PUT"
                },
                {
                    "key": "Access-Control-Allow-Headers",
                    "value": "X-CSRF-Token, X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version"
                }
            ]
        }
    ]
}