Parse instance scenarios into a flat WS URL list

[inancgumus]

The k6-browser can connect to browsers in a round-robin fashion by retrieving data from the K6_INSTANCE_SCENARIOS environment variable.

Problem

Currently, we consider a list of WS URLs.

However, instead of receiving a flat list of WS URLs, we will receive the following minified JSON via the K6_INSTANCE_SCENARIOS environment variable:

K6_INSTANCE_SCENARIOS="[{\"id\":\"one\",\"browsers\":[{\"handle\":\"ws://1...\"},{\"handle\":\"ws://2...\"}]},{\"id\":\"two\",\"browsers\":[{\"handle\":\"ws://3...\"}]}]"

The pre-minified JSON looks like the following (where id is a scenario ID/name):

[
    {
        "id": "one",
        "browsers": [
            { "handle": "ws://1..." },
            { "handle": "ws://2..." }
        ]
    },
    {
        "id": "two",
        "browsers": [
            { "handle": "ws://3..." }
        ]
    }
]

Solution

Currently, we don't support other browsers than Chromium. And we don't need to respect the scenario details to pool WS URLs in each scenario. So we can parse the source JSON into the following, a flat list of WS URLs by joining all scenarios into one as follows:

[ "ws://1...", "ws://2...", "ws://3..." ]

With this, we can still use the same feature set in the k6-browser without changing anything else. And we can be ready when we support other browsers (since we'll be getting WS URLs in scenarios based on environmental details like browser types).

Suggestion

Change the IsRemoteBrowser function to parse the scenario-based JSON data into a flat list of WS URLs.

[ankur22]

Now we are reading the WS URL in the mapBrowserToGoja function. The scope is per VU lifecycle? So we're parsing the map once every vu when it's probably ok to parse once and use when we need.

A possible solution to this could be:

1. Parse the ENV variable once. So maybe when we create the RootModule?
2. Keep the list of WS URLS in the RootModule
3. Pass a reference to the list to the VUmodule when called to NewInstanceModule (same way we do for pidRegistry)
4. And then for each iteration we can call something like.... vu.IsRemoteBrowser() Which would return true/false if it's remote, and if it is remote then it will return one WS URL randomly from the initially parsed list.

[inancgumus]

Hey, @ankur22! Thanks for tackling this 🙇

At this point, our primary goal is to ensure everything works smoothly with the BE data. To do this, we can easily transform the instance scenario JSON data into a more straightforward list of WS URLs. Simple as that!

I really like the solution you proposed! 😊 However, I think it might be a good idea to tackle them separately, perhaps in a different issue.