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Chapter 22. Provisioning rate limits
Each APIcast instance has its own local authorization cache. The first call is always authorized against 3scale before passing the call to the API backend for a specific combination of service, metric, and credentials.
If the response is successful, it stores an "OK" in the local cache for this combination. APIcast updates the cache after getting a response from the API backend, then uses it to authorize subsequent calls.
If a request to 3scale fails because of wrong credentials, the "OK" status is removed from local cache. With one instance of APIcast, you can exceed the limit by one call, and with N instances, you can exceed by N.
Rate limits per minute start at the second zero on the world clock.
Rate limits allow you to throttle access to your API resources, products and backends. You can configure different limits for separate developer segments through the use of application plans.
Once you have rate limits in place, these limits will control the responses a developer receives when they make authorization request calls to the 3scale back end.
22.1. Configuring the application plan
If you do not have an application plan defined yet, create one first. Otherwise, select the plan you want to set rate limits for and click edit.
For more details about creating application plans, see Application plans.
22.2. Setting the rate limits
To set the rate limits:
- Navigate to [Your_product_name] > Overview > Applications > Application plan.
- Click on the name of the application plan you want to configure.
- Scroll down to Metrics, Methods, Limits and Pricing Rules.
- Click on Limits.
- Configure the limits on the product or the backend level.
- When you are finished setting the limits you require, save your changes by clicking Update Application plan.
22.3. Putting the new rate limits into action
Now that you have your rate limits defined, the following will happen:
- If you have alerts configured, the new limits will be used to decide when notifications are sent.
- When you exceed the number of calls to the 3scale back end, the limits are considered and you will see the relevant error message. For more details about APIcast error messages, see Configuring error messages.
Once your rate limits are operational, you will see the users who are reaching the limits on your dashboard, making it quick and easy to check for potential plan upgrade candidates. For more information about soft and hard limits, refer to the Getting Started guide in Configure your API access policies with application plans for the Advanced path.
22.4. More information
Besides setting rate limits, you can also set variable pricing rules for the same metrics - see provision paid plans.
