downstream

Property Manager name: Downstream Cacheability
Behavior version: The v2024-01-09 rule format supports the downstream_cache behavior v1.2.
Rule format status: GA, stable
Access: Read/Write
Allowed in includes: Yes

Specify the caching instructions the edge server sends to the end user's client or client proxies. By default, the cache's duration is whichever is less: the remaining lifetime of the edge cache, or what the origin's header specifies. If the origin is set to no-store or bypass-cache, edge servers send cache-busting headers downstream to prevent downstream caching.

Option	Type	Description	Requires
`behavior`	enum	Specify the caching instructions the edge server sends to the end user's client.		{"displayType":"enum","options":["ALLOW","MUST_REVALIDATE","BUST","TUNNEL_ORIGIN","NONE"],"tag":"select"}
	`ALLOW`	The value of `allow_behavior` chooses the caching method and headers to send to the client.
	`MUST_REVALIDATE`	This equates to a `Cache-Control: no-cache` header, which allows caching but forces the client browser to send an `if-modified-since` request each time it requests the object.
	`BUST`	Sends cache-busting headers downstream.
	`TUNNEL_ORIGIN`	This passes `Cache-Control` and `Expires` headers from the origin to the downstream client.
	`NONE`	Don't send any caching headers. Allow client browsers to cache content according to their own default settings.
`allow_behavior`	enum	Specify how the edge server calculates the downstream cache by setting the value of the `Expires` header.	`behavior` is `ALLOW`	{"displayType":"enum","options":["LESSER","GREATER","REMAINING_LIFETIME","FROM_MAX_AGE","FROM_VALUE","PASS_ORIGIN"],"tag":"select"} {"if":{"attribute":"behavior","op":"eq","value":"ALLOW"}}
	`LESSER`	Sends the lesser value of what the origin specifies and the edge cache's remaining duration. This is the default behavior.
	`GREATER`	Sends the greater value of what the origin specifies and the edge cache's remaining duration.
	`REMAINING_LIFETIME`	Sends the value of the edge cache's remaining duration, without comparing it to the origin's headers.
	`FROM_MAX_AGE`	Sends the `cache:max-age` value applied to the object, without evaluating the cache's duration.
	`FROM_VALUE`	Sends the value of the edge cache's duration.
	`PASS_ORIGIN`	Sends the value of the origin's header, without evaluating the edge cache's duration.
`ttl`	string (duration)	Sets the duration of the cache. Setting the value to `0` equates to a `no-cache` header that forces revalidation.	`allow_behavior` is `FROM_VALUE`	{"displayType":"string","tag":"input","type":"text"} {"if":{"attribute":"allowBehavior","op":"eq","value":"FROM_VALUE"}}
`send_headers`	enum	Specifies the HTTP headers to include in the response to the client.	`behavior` is `ALLOW`	{"displayType":"enum","options":["CACHE_CONTROL_AND_EXPIRES","CACHE_CONTROL","EXPIRES","PASS_ORIGIN"],"tag":"select"} {"if":{"attribute":"behavior","op":"eq","value":"ALLOW"}}
	`CACHE_CONTROL_AND_EXPIRES`	Sends both `Cache-Control` and `Expires` header.
	`CACHE_CONTROL`	Sends only the origin's `Cache-Control` header.
	`EXPIRES`	Sends only the origin's `Expires` header.
	`PASS_ORIGIN`	Sends the same set of `Cache-Control` and `Expires` headers received from the origin.
`send_private`	boolean	Adds a `Cache-Control: private` header to prevent objects from being cached in a shared caching proxy.	`behavior` is either: `ALLOW`, `MUST_REVALIDATE` AND `send_headers` is not `EXPIRES`	{"displayType":"boolean","tag":"input","type":"checkbox"} {"if":{"op":"and","params":[{"attribute":"behavior","op":"in","value":["ALLOW","MUST_REVALIDATE"]},{"attribute":"sendHeaders","op":"neq","value":"EXPIRES"}]}}