Re: [PATCH 2/3] qga: Add optional stream-output argument to guest-exec

[Daniel P . Berrangé]

On Mon, Sep 18, 2023 at 04:54:22AM -0600, Daniel Xu wrote:
> Currently, commands run through guest-exec are "silent" until they
> finish running. This is fine for short lived commands. But for commands
> that take a while, this is a bad user experience.
> 
> Usually long running programs know that they will run for a while. To
> improve user experience, they will typically print some kind of status
> to output at a regular interval. So that the user knows that their
> command isn't just hanging.
> 
> This commit adds support for an optional stream-output parameter to
> guest-exec. This causes subsequent calls to guest-exec-status to return
> all buffered output. This allows downstream applications to be able to
> relay "status" to the end user.
> 
> If stream-output is requested, it is up to the guest-exec-status caller
> to keep track of the last seen output position and slice the returned
> output appropriately. This is fairly trivial for a client to do. And it
> is a more reliable design than having QGA internally keep track of
> position -- for the cases that the caller "loses" a response.

I can understand why you want this incremental output facility,
but at the same time I wonder where we draw the line for QGA
with users needing a real shell session instead.

When there is a long lived command, then IMHO it is also likely
that there will be a need to kill the background running command
too.

We quickly end up re-inventing a shell in QGA if we go down this
route.


With regards,
Daniel
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