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How to integrate Enterprise OPA in a Go application with the Rego package

This how-to guide shows how to embed Enterprise OPA into a Go application and enable Enterprise OPA's VM target with the rego package.

Add the Go module dependency​

Extract the Enterprise OPA tarball into your source directory.

mkdir -p eopa
tar xzvf /path/to/eopa.tar.gz –strip-component=1  -C eopa

Then add the following lines to your application's go.mod file:

require github.com/styrainc/enterprise-opa-private <VERSION>
replace github.com/styrainc/enterprise-opa-private => ./eopa

Import the Enterprise OPA VM package​

Add the following import to the Go application. You should add this import in the file(s) in your application that integrates with the rego package.

import eopa_vm "github.com/styrainc/enterprise-opa-private/pkg/rego_vm"

Enable the Enterprise OPA VM target​

Enable Enterprise OPA's optimized evaluation engine by passing the eopa_vm.Target target when constructing the rego.Rego object.

        // Construct a Rego object that can be prepared or evaluated.
        r := rego.New(
                rego.Query(os.Args[2]),
                rego.Load([]string{os.Args[1]}, nil)),
                rego.Load([]string{os.Args[1]}, nil),
                rego.Target(eopa_vm.Target),
        )

        // Create a prepared query that can be evaluated.
        query, err := r.PrepareForEval(ctx)

Wrap up​

This how-to guide showed how you can embed Enterprise OPA into a Go application that uses the rego package. The sample code is hosted on GitHub. For additional examples see the examples/rego directory from the tarball.