firebase.json

{
  "functions": {
    "predeploy": [
      "npm --prefix \"$RESOURCE_DIR\" run lint",
      "npm --prefix \"$RESOURCE_DIR\" run build"
    ]
  },
  "hosting": {
    "public": "public",
    "ignore": ["**/.*", "**/node_modules/**"],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ],
    "headers": [
      // Set up cache headers based on:
      //
      // https://www.gatsbyjs.com/docs/how-to/previews-deploys-hosting/deploying-to-firebase/
      {
        "source": "**/*",
        "headers": [
          {
            "key": "cache-control",
            "value": "public, max-age=0, must-revalidate"
          }
        ]
      },
      {
        "source": "static/**",
        "headers": [
          {
            "key": "cache-control",
            "value": "public, max-age=31536000, immutable"
          }
        ]
      },
      {
        "source": "**/*.@(css|js)",
        "headers": [
          {
            "key": "cache-control",
            "value": "public, max-age=31536000, immutable"
          }
        ]
      },
      {
        "source": "sw.js",
        "headers": [
          {
            "key": "cache-control",
            "value": "public, max-age=0, must-revalidate"
          }
        ]
      },
      {
        "source": "page-data/**",
        "headers": [
          {
            "key": "cache-control",
            "value": "public, max-age=0, must-revalidate"
          }
        ]
      }
    ]
  }
}