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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.

StageCategoryMessage
parsingrego_parse_errorvar 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+):

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. Both of these cases are easy to fix once identified.

Community​

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