Compute resource limits

This guide details Fastly resource limits for Compute services. These limits change based on whether or not you've purchased one of our packaged offerings or you're using a trial account.

NOTE

In addition to the limits described here, Compute services can also be limited by the products or platform services that you access through your application code. Check out our network services resource limits for additional details.

Port limits

Compute services accept client connections on port 443 only. This is different from VCL services, which support client connections on port 80.

NOTE

If your Compute service receives a request on port 80, Fastly automatically returns a 308 Permanent Redirect response status with the Location header indicating the HTTPS version of the same URL in a Location header.

Default limits

ItemLimitScope
Maximum compiled package size100MBper service
Maximum cached object size100MBper object
Maximum CPU time available to a single request instance50msper execution
Maximum runtime for a single request instance2 min (60s for trial accounts)per execution
Maximum memory consumption1M bytes stack, 128MB heapper execution
Maximum number of dictionary lookups16per execution
Maximum number of backend requests32 (10 for trial accounts)per execution
Maximum number of dynamic backends200per service
Vary rules8per cache object
Maximum length of a request header128KBper header
Maximum length of a response header128KBper header
Maximum length of a method name8192 bytesper request
Maximum length of a URL8192 bytesper request

An execution refers to a single instance of a Compute program being executed, normally in response to a client HTTP request. Separate limits also apply to the use of log tailing with Compute services.

Service chain limits

ItemLimitImplications
Service chains and hops20 hops, 6 unique servicesRead our developer information about loop detection for more info.

Edge data storage limits

Limits for each of our edge data storage options differ if you've purchased a package offering or are using a product or feature trial.

Config Store

Config Store is included with your Compute service with the following limitations.

ItemTrial limitPaid account limitImplications
Config stores15Paid accounts can purchase additional stores for a monthly fee.
Config store entries (per store)100500An error informs you that you've exceeded the limit.
Config store key length255 characters255 charactersAn error informs you that you've exceeded the limit.
Config store value length8,000 characters8,000 charactersAn error informs you that you've exceeded the limit.
Config store write operations100 writes per hour100 writes per hourWrite limits are shared with all other Fastly API calls. Exceeding the limit will result in an API limit error. Refer to API rate limiting for more info.

KV Store

KV Store is an add-on and is priced in addition to Compute services. The number of KV Stores is limited to the account’s available resources allotment. The following limitations also apply:

  • Values stored in KV Store items are limited by default to 25MB, but that limit can be raised to as much as 100MB upon request. Contact your account manager or sales@fastly.com for more information.
  • Metadata stored in KV Store items is limited to 2000 bytes and must be composed of Unicode characters encoded using UTF-8.
  • KV Stores have a rate limit of 1,000 writes per second per store, and 5,000 reads per second per store. These are soft limits for the durable store and they auto-scale as needed.
  • KV Store items have a rate limit of 1 write per second per item.
  • KV Store item batch requests have a limit of 100,000 items per request.
  • KV Stores provide eventual consistency, which means that reading a key immediately after writing it may not return the updated value.

Store name limitations

  • KV store names must begin with an ASCII alphabetical character and must be composed of Unicode characters encoded using UTF-8.
  • Store names cannot contain Unicode control characters.
  • Store names are limited to 255 bytes.

Key limitations

  • Keys cannot start with .well-known/acme-challenge/, ., or ...
  • Key names can contain any sequence of valid Unicode characters of length 1-1024 bytes when UTF-8 encoded. The following characters can be used in key names but can't be searched in a prefix query string: !, ", $, %, &, (, ), *, +, ,, /, \, :, <, =, >, @, [, ], `, {, }.
  • Keys cannot use Unicode characters 0 through 32, 65534, and 65535 as single-character key names.
  • The following characters cannot be used in key names:
    • #, ;, ?, ^, and |
    • line feed (LF) characters
    • carriage-return (CR) characters
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