Hosting Updates on Your Servers
For simplicity, the rest of this article will refer to hosting an update for the Android platform, but you could swap out Android for iOS at any point and everything would still be true.
First, you’ll need to export all the static files of your update so they can be served from your CDN. To do this, run
expo export --public-url <server-endpoint> in your project directory and it will output all your app’s static files to a directory named
dist. In this guide, we will use
https://expo.github.io/self-hosting-example as our example server endpoint. Asset and bundle files are named by the MD5 hash of their content. Your output directory should look something like this now:
│ └── 1eccbc4c41d49fd81840aef3eaabe862
Once you've exported your update's static files, you can host the contents on your own server. For example, in your
output directory, an easy way to host your own files is to push the contents to GitHub. You can enable GitHub Pages
to make your app available at a base URL like https://username.github.io/project-name
. To host your files on GitHub, you'd do something like this:
# run this from your project directory
expo export --public-url https://expo.github.io/self-hosting-example
# commit output directory contents to your repo
git init && git remote add origin email@example.com:expo/self-hosting-example.git
git add * && git commit -m "Update my app with this JS bundle"
git push origin master
To setup a QR code to view your hosted update, or if you want to host your files locally, follow the instructions below in the 'Loading QR Code/URL in Development' section.
On some hosting services such as AWS
, you'll need to explicitly set the header
so that updates
work correctly. Otherwise Updates.checkForUpdateAsync()
will fail with the error "Failed to fetch new update"
Here's an example of firebase.json
configuration, with a deploy target
+ "headers": [
+ "source": "**/*.js",
+ "headers": [
+ "key": "Content-Type",
# export your app locally
expo export --public-url https://my-app-native.firebaseapp.com/
# deploy the app to firebase
firebase deploy --only hosting:native -m "Deploy my app"`
To configure your standalone binary to pull updates from your server, you’ll need to define the URL where you will host your index.json
file. When using EAS Build, just set the
updates.url property in app.json
to point to that url.
Are you using the classic build system? (
With the classic build system, you need to pass the URL to your hosted
index.json file to the
expo build command.
You can also load an update hosted on your own servers as a QR code/URL into the Expo mobile client for development purposes.
The URI you’ll use to convert to QR code will be deeplinked using the
exp protocol. Both
exp deeplink into the mobile app and perform a request using HTTPS and HTTP respectively. You can create your own QR code using an online QR code generator from the input URI.
expo export in dev mode and then start a simple HTTP server in your output directory:
# Find your local IP address with `ipconfig getifaddr en0`
# export static app files
expo export --public-url http://`ipconfig getifaddr en0`:8000 --dev
# cd into your output directory
# run a simple http server from output directory
python -m SimpleHTTPServer 8000
exp://192.xxx.xxx.xxx:8000/android-index.json (find your local IP with a command like
ipconfig getifaddr en0)
If you are loading in your update into a development build by passing in a URL string, you will need to pass in an URL pointing to your JSON manifest file.
Here is an example URL from localhost:
When Expo CLI bundles your update, minification is always enabled. In order to see the original source code of your update for debugging purposes, you can generate source maps. Here is an example workflow:
expo export --dump-sourcemap --public-url <your-url>. This will also export your bundle sourcemaps in the bundles directory.
- A debug.html file will also be created at the root of your output directory.
- In Chrome, open up debug.html and navigate to the
Source tab. In the left tab there should be a resource explorer with a red folder containing the reconstructed source code from your bundle.
By default, all assets are hosted from an
path resolving from your
). You can override this behavior in the
field of your
. All relative URL's will be resolved from the
Most of the fields in the index.json files are the same as in app.json. Here are some fields that are notable in index.json:
publishedTime: These fields are generated by
expo export and used to determine whether or not an update should occur.
bundleUrl: This points to the path where the app's bundles are hosted. They are also used to determined whether or not an update should occur.
slug: This should not be changed. Your app is namespaced by
slug, and changing this field will result in undefined behavior in the Expo SDK components such as
assetUrlOverride: The path which assets are hosted from. It is by default
./assets, which is resolved relative to the base
public-url value you initially passed in.