[QUESTION] Sending requests with dynamic body

[AVoskoboinikov]

Question

Hi @tsenart

I have a question about request body.
Lets say I have API to create an entity in db and the request body looks like

{
    entityName: "burger"
    entityId: 42
}

Now I want to test that API and send 100 requests. The problem is that field entityId has to be unique.
So, my question is - is there any way to generate unique value for field before sending request to API endpoint?

[tsenart]

There sure is. Use JSON target format which allows you to set the request body of each target. Paired with the jq tool, it should be fairly easy to do what you need.

[tsenart]

Here's a specific incantation for you:

jq -ncM 'while(true; .+1) | {method: "POST", url: "http://localhost:6060", body: {entityName: "burger", entityId: .} | @base64}'  | \
vegeta attack -lazy --format=json -duration=30s | tee results.bin | vegeta report

[AVoskoboinikov]

Thanks @tsenart
And is there any way to do similar trick when using Vegeta as lib without cli?

[tsenart]

Yes. A vegeta.Targeteris just a Plain Old Function. Hence, you can define whatever you want in there.

tr := func(id uint64) vegeta.Targeter {
    type entity struct {
        Name string `json:"entityName"`
        ID   uint64 `json:"entityId"`
    }
    return func(t *Target) (err error) {
        t.Method = "POST"
        t.URL    = "http://localhost:6060"

        t.Body, err = json.Marshal(&entity{
            Name: "burger",
            ID:    atomic.AddUint64(&id, 1),
        })

        return err
    }
}(0)

[AVoskoboinikov]

Great. Thanks, that works for me!

[akashdas2019]

@base64}'  

I have a big json and hence I cannot add the post request and body and header here.
I need to pass that via target.txt file. So in that case how to modify the command so that the order_number field in that is unique everytime.

[tsenart]

@akashdas2019: Better write a script or little program that does that.

[aryahmph]

Yes. A vegeta.Targeteris just a Plain Old Function. Hence, you can define whatever you want in there.

tr := func(id uint64) vegeta.Targeter {
    type entity struct {
        Name string `json:"entityName"`
        ID   uint64 `json:"entityId"`
    }
    return func(t *Target) (err error) {
        t.Method = "POST"
        t.URL    = "http://localhost:6060"

        t.Body, err = json.Marshal(&entity{
            Name: "burger",
            ID:    atomic.AddUint64(&id, 1),
        })

        return err
    }
}(0)

How about doing with 2 requests ?