CODEWITHSUNDEEP
goopen-policy-agentrego
bogg
bogg

Reputation: 41

OPA (Rego) as Go lib: How to apply external data?

I followed the example of https://www.openpolicyagent.org/docs/latest/#5-try-opa-as-a-go-library. Important code snippets:

r := rego.New(
rego.Query("x = data.example.allow"),
rego.Load([]string{"./example.rego"}, nil)
...
rs, err := query.Eval(ctx, rego.EvalInput(input))
...

How can I add external data (data.json) such that I can use, e.g., data.wantedName in the rego policy to access it?

I tried to read through the go doc and the examples but I couldn't find any helpful information.

Thanks!

Upvotes: 2

Views: 3002

Answers (1)

sr_
sr_

Reputation: 602

Have you seen the docs on rego.Store() and this example?

Something along these lines should do the trick for simple cases:

    data := `{
        "example": {
            "users": [
                {
                    "name": "alice",
                    "likes": ["dogs", "clouds"]
                },
                {
                    "name": "bob",
                    "likes": ["pizza", "cats"]
                }
            ]
        }
    }`

    var json map[string]interface{}

    err := util.UnmarshalJSON([]byte(data), &json)
    if err != nil {
        // Handle error.
    }

    store := inmem.NewFromObject(json)

    // Create new query that returns the value
    rego := rego.New(
        rego.Query("data.example.users[0].likes"),
        rego.Store(store))

You could implement your own storage for more intricate uses, but that's going to be a lot more involved. If you get by with feeding inmem.NewFromObject() stores into rego.New(), you should try that first.

Upvotes: 7

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