Google recommends that you follow these best practices when administering and running your app.
Securing API keys
You need an API key to use our online services, and its use allows Google to meter your usage. We recommend restricting your API keys to prevent unauthorized use.
Types of API key restrictions
There are two types of API key restrictions, and you can use them both at the same time.
|Restriction type||Restricts key usage to|
|API restriction||A particular API.|
|Application restriction||Particular IP addresses, web sites, or app.|
API key restriction recommendations
We recommend that you commission separate API keys for the following scenarios.
|Your back-end game servers calls the Playable Locations API to retrieve playable locations.||Configure a key with two restrictions:
|The Android version of your app calls the Maps SDK for Unity to retrieve geo data.||Configure a key with an application restriction to allow calls from only the Android version of your app.|
|The iOS version of your app calls the Maps SDK for Unity API to retrieve geo data.||Configure a key with an application restriction to allow calls from only the iOS version of your app.|
For more information, see API sercurity best practices.
To setup API key restrictions
- Visit the credentials panel in the Google Cloud Console.
- Select the API key that you want to set a restriction on. The API key property page appears.
- Under Key restrictions, select the Application restrictions tab,
and then select one of the four applications restriction types.
Restriction type Description HTTP referrers Accept requests from the list of websites that you supply. IP addresses Accept requests from the list of web server IP addresses that you supply. Android apps Add your package name and SHA-1 signing-certificate fingerprint to restrict usage to your Android app. iOS apps Accept requests from the iOS app with the bundle identifier that you supply.
- Under Key restrictions, select the API restrictions tab, and then select the API that you want to restrict your API key to.
- Click Save.
Support API key updates
Make sure that you have infrastructure in place to update API keys across your serving stack. That way, your game can recover if your API key is compromised, and you need to renew it on short notice.
Use separate keys for each application, so you can easily swap a key in one without affecting other apps.
Game server safety recommendations
When the Playable Locations API server experiences an outage for any reason, problems occur when it comes back online—when multiple game servers attempt to reconnect to it at the same time. Such a QPS spike can send the server into DoS mode, which exacerbates the situation by blocking incoming traffic.
To mitigate this situation, Google asks that you implement Binary Exponential Back-off on your game server. It's a systematic approach to spacing-out your connection retries. Specifically, you would implement an algorithm that waits N seconds after a failed reconnection attempt before trying again. If the next attempt fails, then your algorithm doubles the waiting period and then tries again. If the next attempt fails, then your algorithm again doubles the waiting period, and then tries again. You continue doubling the waiting period after each attempt--until your final attempt succeeds.
Handling HTTP return status codes
You should implement binary exponential back-off for some HTTP return codes, but not all of them.
- These are client errors that generally don't recover, so retrying failed requests that produce this error codes won't work. You should catch these kinds of errors during testing.
- This is a resource exhausted error that occurs when you begin running out of API quota. To see your project's API QPS limits, visit Google APIs Quotas.
- These are the server-side errors—the kind of errors that exponential back-off is most useful for.