功能

Operator/Function	Definition	Example	Description
==	Equals	request.size == 200
!=	Not Equals	request.auth.principal != "admin"
`\	\	`	Logical OR	`(request.size == 200) \	\	(request.auth.principal == "admin")`
&&	Logical AND	(request.size == 200) && (request.auth.principal == "admin")
[ ]	Map Access	request.headers["x-id"]
`\	`	First non empty	`source.labels[“app”] \	source.labels[“svc”] \	"unknown"`
match	Glob match	match(destination.service, "*.ns1.svc.cluster.local")	Matches prefix or suffix based on the location of *
email	Convert a textual e-mail into the EMAIL_ADDRESStype	email("[email protected]")	Use the email function to create an EMAIL_ADDRESSliteral.
dnsName	Convert a textual DNS name into the DNS_NAMEtype	dnsName("www.istio.io")	Use the dnsName function to create a DNS_NAMEliteral.
ip	Convert a textual IPv4 address into the IP_ADDRESS type	source.ip == ip("10.11.12.13")	Use the ip function to create an IP_ADDRESS literal.
timestamp	Convert a textual timestamp in RFC 3339 format into the TIMESTAMP type	timestamp("2015-01-02T15:04:35Z")	Use the timestamp function to create a TIMESTAMPliteral.
uri	Convert a textual URI into the URI type	uri("http://istio.io")	Use the uri function to create a URI literal.
.matches	Regular expression match	"svc.*".matches(destination.service)	Matches destination.service against regular expression pattern "svc.*".
.startsWith	string prefix match	destination.service.startsWith("acme")	Checks whether destination.service starts with "acme".
.endsWith	string postfix match	destination.service.endsWith("acme")	Checks whether destination.service ends with "acme".

举例

Expression	Return Type	Description
`request.size \	200`	int	request.size if available, otherwise 200.
request.headers["X-FORWARDED-HOST"] == "myhost"	boolean
`(request.headers["x-user-group"] == "admin") \	\	(request.auth.principal == "admin")`	boolean	True if the user is admin or in the admin group.
`(request.auth.principal \	"nobody" ) == "user1"`	boolean	True if request.auth.principal is “user1”, The expression will not error out if request.auth.principal is missing.
source.labels["app"]=="reviews" && source.labels["version"]=="v3"	boolean	True if app label is reviews and version label is v3, false otherwise.