Applications often need to serve static files such as JavaScript, images, and CSS in addition to handling dynamic requests. Apps in the standard environment can serve static files from a Google Cloud option like Cloud Storage, serve them directly, or use a third-party content delivery network (CDN).Hosting your static site on Google Cloud can cost less than using a traditional hosting provider, as Google Cloud provides a free tier

## Serving files from Cloud Storage
Cloud Storage can host static assets for dynamic web apps. The benefits of using Cloud Storage instead of serving directly from your app include:
- Cloud Storage essentially works as a content delivery network. This does not require any special configuration because by default anyreadable object is cached in the global Cloud Storage network

- Your app's load will be reduced by offloading serving static assets to Cloud Storage. Depending on how many static assets you have and the frequency of access, this can reduce the cost of running your app by a significant amount

- Bandwidth charges for accessing content can often be less with Cloud Storage

You can upload your assets to Cloud Storage by using the
gsutil command line tool
or the Cloud Storage API

The Google Cloud Client Library provides an idiomatic Go 1.11 client to Cloud Storage, for storing and retrieving data with Cloud Storage in an App Engine app

 Example of serving from a Cloud Storage bucket
This simple example creates a Cloud Storage bucket and uploads static assets using Google Cloud CLI:
Create a bucket. It's common, but not required, to name your bucket after your project ID. The bucket name must be globally unique

gsutil mb gsyour-bucket-name>
Set the ACL to grant read access to items in the bucket

gsutil defacl set public-read gsyour-bucket-name>
Upload items to the bucket. The
rsynccommand is typically the fastest and easiest way to upload and update assets. You could also use
cp

gsutil -m rsync -r ./static gsyour-bucket-name>/static
You can now access your static assets via
httpsstorage.googleapis.com//static

For more details on how to use Cloud Storage to serve static assets, including how to serve from a custom domain name, refer to How to Host a Static Website

 Serving files from other Google Cloud services
You also have the option of using Cloud CDN or other Google Cloud storage services

## Serving files directly from your app
To serve static files for Go 1.11 in the standard environment,
you define the handlers in your
app.yaml file using either the
static_dir
or
static_files
elements

The content in the static files or static directories are unaffected
by the scaling settings in your
app.yaml file. Requests to static files or
static directories are handled by the App Engine infrastructure
directly, and do not reach the language runtime of the application

 Configuring your static file handlers
To configure your app to serve the
./public directory from the
/static URL,
you define a handler in your
app.yaml file

The following demonstrates how to serve the static files of a sample
app's
./public directory. The template for this app's
index.html page
instructs the browser to load the
main.css file, for example:

The
./public directory is defined in the
static_dir element of the project's
app.yaml file:
handlers: - url: /favicon\.ico static_files: favicon.ico upload: favicon\.ico - url: /static static_dir: public - url:secure: always redirect_http_response_code: 301 script: auto
The
handlers section in the above example handles three URL patterns:
The
/favicon.icohandler maps a request specifically for
/favicon.icoto a file named
favicon.icoin the app's root directory

The
/statichandler maps requests for URLs that start with
/static. When App Engine receives a request for a URL beginning with
/static, it maps the remainder of the path to files in the
./publicdirectory. If an appropriate file is found in the directory, the contents of that file are returned to the client

The
 handler matches all other URLs and directs them to your app

URL path patterns are tested in the order they appear in
app.yaml, therefore
the pattern for your static files should be defined before the
 pattern

For more information, see the
app.yaml
reference

## Serving from a third-party content delivery network
You can use any external third-party CDN to serve your static files and cache dynamic requests but your app might experience increased latency and cost

For improved performance,