rego_parse_error: var cannot be used for rule name

This cause for this error isn't always obvious at first glance, but as any parser error, this one is caused by an error in the syntax of a Rego policy, and one around rule declarations specifically. Look closely at the rule head for anything that might be missing! The following examples will help demonstrate the most common causes for this error.

Stage	Category	Message
parsing	rego_parse_error	var cannot be used for rule name

Examples

The below example shows the most likely occurrence of this error: having forgotten to import if, either via import future.keywords.if, or import rego.v1 (OPA v0.59.0+):

note

Some that in OPA versions >=1.0.0, imports for if etc. are no longer required.

package policy

allow if {
    input.request.method == "GET"
    input.request.path == ["users"]
}

Another example could be having forgotten to add an assignment operator between the rule name and the value intended for assignment:

package policy

import future.keywords.if

# note the missing `:=` between internal_user and email
internal_user email if {
    endswith(email, "@acmecorp.com")

    email := input.user.email
}

How To Fix It

If caused by a missing import like the if keyword, simply add the import at the top of your package. Other cases are likely caused by having forgotten to add an assignment operator between the rule name and the value to assign. Once you have identified the cause, fix the syntax error or adding the missing import will address the issue.

Community

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