[Programming Model] Entry Point

[asavaritayal]

Script File

PowerShell support for Functions will support a run file of .ps1 format. We'll use the workflow below to determine which file to run:

If the "scriptFile" attribute is set in function.json
Else if the project contains a single .ps1 file
Else if run.ps1 is present
Else throw an error

Entry Point

Instead of running a plain script, we'll define a method for the runtime to invoke during an execution. We'll use the workflow below to determine which function to run:

If the "entryPoint" attribute is set in function.json
Else if Run() is present
Else throw an error

[TylerLeonhardt]

Thanks for opening this @asavaritayal! Quick question... I noticed that when no entry point is specified, our language worker receives that entryPoint is set to empty string. I've been using this to determine whether to run the script or run a function within the script. That part is easy.

My question for you is... is there any indication from the functions side that would help us determine if we should run the script as the function or a (specifically) Run function within the script?

From the PowerShell side, we could probably do this by analyzing the script to check if a Run function exists... but I'd like to call that out of scope for ignite on the basis that there are bigger fish to fry.

[TylerLeonhardt]

I also have a similar question for Else if the project contains a single .ps1 file. Does the host provide the path to the single .ps1 as it does when a run.ps1 is available or will we have to add logic to support this?

[asavaritayal]

My question for you is... is there any indication from the functions side that would help us determine if we should run the script as the function or a (specifically) Run function within the script?

In my opinion, we don't explicitly need to support both the formats. As part of the programming model, we can decide to only support a Run function as an entrypoint, since it is fairly simple to go from scripting to this format.

I also have a similar question for Else if the project contains a single .ps1 file. Does the host provide the path to the single .ps1 as it does when a run.ps1 is available or will we have to add logic to support this?

@pragnagopa to confirm if the runtime provides this information

[pragnagopa]

As a starting point, you can define what is the entry point for a script. Allow users to specify entry point and default to run.ps1? if not present

[asavaritayal]

As a starting point, you can define what is the entry point for a script. Allow users to specify entry point and default to run.ps1? if not present

I think Tyler's question is - if no scriptFile is defined in function.json and no run.ps1 is present, can the runtime identify the path to the first *.ps1 module present in the function directory ?

[pragnagopa]

Nope. Runtime does not have any logic specific to a language worker.

[TylerLeonhardt]

@pragnagopa the host seems to be able to figure out that there's a run.ps1 present when scriptFile is not set - I'm guessing there's some logic that just looks for a run.{extension} or simply run.*. Is that correct?

[TylerLeonhardt]

@asavaritayal - so here's what I have working so far:

Script File

If the "scriptFile" attribute is set in function.json
Else if run.ps1 is present
Else throw an error

Entry Point

If the "entryPoint" attribute is set in function.json
Else throw an error

You'll note that the two items that are missing are:

Else if the project contains a single .ps1 file - this is relatively straight forward for us to implement, but I'd need to see what the host sends us if there is no run.ps1.

Else if Run() is present - as I mentioned above, this would be a bit tedious to implement so I'd like to defer this for now in favor of higher pri items.

[pragnagopa]

I will look into it and confirm. My best guess is it is following the same pattern as c# script file where it defaults to run.csx

[asavaritayal]

@pragnagopa do you have an update on this?

Else if the project contains a single .ps1 file - this is relatively straight forward for us to implement, but I'd need to see what the host sends us if there is no run.ps1.

[pragnagopa]

@tylerl0706 - Can you add this scenario as a test and check what is the entry point you get from host when it is specified?

[TylerLeonhardt]

I tested this out and the host gives the path of the single ps1 in the directory. So that works as expected. (I renamed the run.ps1 to foo.ps1 in our example and it worked perfectly)

So we really have all scenarios except for:

Else if Run() is present which would be tedious to implement and I don't think makes a lot of sense for powershell since you can very easily declare parameters of a script by putting a param block at the top.