[feature request] juju config --wait

[Marian Gasparovic]

It would be great for automation if juju config could block until change is finished (change hook finished)
Something like
`juju config --wait app key=value`

Right now we are forced to hack around this thing.

[Richard Harding (rharding)]

Is there any reason in particular this doesn't fall into the normal use of the juju wait plugin to make changes, then wait for them to settle vs needing it on a single specific call? My concern is that a config-change could trigger different relation updates and such but it would be a bit of a "false promise" that it's "done".

[Jason Hobbs (jason-hobbs)]

We ended up needing it for this case:

#1. juju wait until everything is settled
#2. issue a juju config run=true on the glance-simplestreams-sync app to turn on syncing. (this is actually a bug in the gsss or glance charms: bug 1861005)
#3. wait for the config hook to complete
#4. sleep 60 seconds because the config hook sets up a timer that starts the syncing
#5. use juju wait to wait for the application status to show the syncing has completed

[Marian Gasparovic (marosg)]

Basically any situation when you need to change a config and then run a command which depends on that config to be applied.

[Richard Harding (rharding)]

I'm missing why the pattern of

  #1: juju wait until it's settled
  #2: issue config change
  #3: juju wait until it's settled again

Doesn't work out? This seems like another form of juju wait with some narrower context (the config-changed hook)?

[Marian Gasparovic (marosg)]

Well, because we had to bypass another race condition in glance-simplestreams-sync we set it to run:false. Then waited till juju was settled and set run to true. So at this stage juju is stable and it would continue immediately before gsss downloads files

[Tim Penhey (thumper)]

In a distributed async system there is no guarantee that it will ever be
processed in a timely manner. Especially if an agent is down.

I don't think adding a --wait option to changing config is reasonable.

On Wed, Mar 11, 2020 at 4:21 AM Marian Gasparovic <
<email address hidden>> wrote:

> Well, because we had to bypass another race condition in glance-
> simplestreams-sync we set it to run:false. Then waited till juju was
> settled and set run to true. So at this stage juju is stable and it
> would continue immediately before gsss downloads files
>
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> Title:
> [feature request] juju config --wait
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[Canonical Juju QA Bot (juju-qa-bot)]

This bug has not been updated in 2 years, so we're marking it Low importance. If you believe this is incorrect, please update the importance.