Example proposal for Issue #731

[dburriss]

This is linked to the issue described in #731 and is just for demo purposes.

I have encountered this issue a few times with Farmer and do not know of an elegant solution.
Something like this can get you out in a pinch but it requires knowing what the builder is setting, which leaks the details. It's also just not very elegant.

let mutable myWebApp = webApp {
            name "myWebApp"
            service_plan_name "myServicePlan"
            setting "myKey" "aValue"
            sku WebApp.Sku.B1
            always_on
            app_insights_off
            worker_size Medium
            number_of_workers 3
            run_from_package
            system_identity
        }
        let disableAlwaysOn = false
        if disableAlwaysOn then 
            myWebApp <- { myWebApp with WebAppConfig.CommonWebConfig.AlwaysOn = true }

An elegant solution would be if we could implement For and Zero in a way that allowed for if in the CE but playing around with it for a few minutes did not work as expected. I have not worked with CEs for a while but not sure if this is even possible for a non-collection based CE.

A simple solution (albeit quite some work) is to take in a value but add an optional parameter.

let expected = false
let template = webApp {
  name "web"
  always_on expected
}

This matches what I usually do in builders in C# where boolean switching takes in a boolean with a default value.

[mattgallagher92]

Thanks @dburriss! I like this approach 🙂 Particularly because it's a very simple change that is backwards compatible.

It will only work for simple on/off cases and not those where we need to pass in more complex data, but is definitely a good idea for them.

As you say, it's potentially quite a lot of work, but would be fairly easy to apply in increments - there's no need to change every Farmer CE in one PR. If you'd like to raise a PR(s) for the cases that you need (or more!), I'm sure that we'll be happy to merge them 🙂

[dburriss]

@mattgallagher92 Ok nice. As I mentioned, I have a usage where I will likely need this flexibility on a couple of resources, so I will make the changes on the CEs for all boolean switches as needed (I will do all on a CE, not just the ones I need ;) )
This will mostly be compute resources e.g. WebApp, Containers, maybe VMs. It has been 4 years since I contributed to Farmer. The codebase is familiar but there are A LOT more resources and the files are A LOT bigger :)