Launchers 101

[John J. Karcher]

On 5/19/22 10:13, Norman Feske wrote:
> Hi John,
> 
>> This seems like it would be a neat function to add to the Leitzentrale
>> GUI - maybe a "Create Launcher" button inside the Component detail,
>> beside "Restart" and "Remove".  ("Edit Config" would probably be nice
>> also.)
> 
> that's a good idea. I wonder, what do you think about the following aspects?

I will be happy to give my thoughts, but I'm still learning and 
experimenting, so I hope more knowledgeable users give theirs also.

> - When creating a launcher for a deployed component, should the
>    start node of the component in managed/deploy automatically be
>    changed to refer to the new launcher?
> 
> - What should happen when deploying a new component that has the
>    same name as an existing launcher? If this is allowed - like today -
>    the start node of the deployed component would differ from the
>    existing launcher. Would Sculpt need to detect this situation,
>    offering an "update launcher" button?
> 
> - Should the reverse operation be supported via a "remove launcher"
>    button - removing a launcher for running component, turning this
>    component into a regular start node of the deploy config?
> 
> Intuitively, I tend to answer those questions with yes to foster the
> consistency of the feature. On the downside, implementing those corner
> cases with their possible intermediate states is not quite easy.
> 
> What do you think?

Yes, those are good questions - finding the balance between flexibility 
and complexity.

Because sometimes we might want to just "save" the current config but 
other times create a "copy" launcher, my initial idea was to ask for the 
launcher name, and maybe a checkbox for "copy" vs. "take over".  Does 
that make sense?

Along those lines, is it possible to display in the component detail the 
name of the launcher it is using, if applicable?  (I don't know if that 
info is readily available or not.)  That might help distinguish between 
the three cases of "create new launcher", "edit running launcher", and 
"copy launcher".

The "Remove Launcher" option seems like a good idea also.

I'm curious about your thoughts on how much of this you want to 
incorporate into Leitzentrale, and where you think an external "Launcher 
Gallery/Editor" tool might make more sense.

> I also like your idea to make the config of a component easily
> customizable without manually diving into the config/deploy or
> config/launcher files. Sculpt's underlying mechanisms actually support
> that today: When adding a customized <config> node inside a <start> node
> in config/deploy, the component observes a config update.
> 
> For example, if you have the pkg/sticks_blue_backdrop deployed (and
> copied /config/managed/deploy to /config/deploy), you can add the
> following snippet to the start node in /config/deploy:
> 
>    <config>
>      <libc/>
>      <vfs> <rom name="genode_logo.png"/> </vfs>
>      <fill color="#223344" />
>      <image png="genode_logo.png" anchor="bottom_right" alpha="150"
>                                   xpos="-20" ypos="-20" />
>    </config>
> 
> You can even change all those attributes on the fly and the backdrop
> adjusts. This way, the backdrop can easily be customized without
> touching any depot content. The machinery it there. But I admit that the
> process is not really intuitive. ;-)
> 
> A button that takes the <config> node from /config/managed/runtime to
> /config/managed/deploy and shows the config in a text editor for live
> editing - that would be quite inviting!

Yes, that's exactly what I was thinking also.  All that dynamic power is 
right there, and popping up just the applicable node in the text editor 
would be really handy.

  Thanks!

   John J. Karcher
   devuser at alternateapproach.com