firebase.json

{
  "firestore": {
    "rules": "firestore.rules",
    "indexes": "firestore.indexes.json"
  },
  "hosting": {
    "public": "build",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [ {
      "source": "**",
      "destination": "/index.html"
    } ],
    "headers": [ {
      "source" : "**/*.@(eot|otf|ttf|ttc|woff|font.css)",
      "headers" : [ {
        "key" : "Access-Control-Allow-Origin",
        "value" : "*"
      } ]
    }, {
      "source" : "**/*.@(jpg|jpeg|gif|png|svg)",
      "headers" : [ {
        "key" : "Cache-Control",
        "value" : "max-age=7200"
      }, {
        "key" : "Access-Control-Allow-Origin",
        "value" : "*"
      } ]
    }, {
      "source" : "404.html",
      "headers" : [ {
        "key" : "Cache-Control",
        "value" : "max-age=300"
      } ]
    } ],
    "cleanUrls": true,
    "trailingSlash": false
  },
  "storage": {
    "rules": "storage.rules"
  }
}