Microbox snap: wrong application creation error ("zip_archive_support" not supported)

[Michele Lo Russo]

I was trying to create an application using a zip archive via CLI with the microbox snap, and accidentally forgot to prepend sudo:

ubuntu@juju-4d0777-prod-anbox-cloud-webdemo-2:~$ amc application create test_application.zip
Error: api extension "zip_archive_support" not supported

But actually, this is not the reason why it failed. The "zip_archive_support" is present indeed:

ubuntu@juju-4d0777-prod-anbox-cloud-webdemo-2:~$ sudo amc info | grep zip
- zip_archive_support

So, this should probably give a different error? (Permission denied, I guess?)

[Gary.Wang (gary-wzl77)]

Hey Michele
The microbox snap is running in strict confined mode, the unix domain socket(/var/snap/microbox/common/ams/server/unix.socket) is owned by ,
```
srw-rw---- 1 root root 0 5月 28 11:00 /var/snap/microbox/common/ams/server/unix.socket
```

That's the reason you encountered the above issue.

For the ams charm(regular deployment), we made some tweaks:

1. created the ams group.
2. added the current login user to that group.
3. changed the group of the Unix domain socket with:
  $ chown :ams /var/snap/ams/common/server/unix.socket

You can do something similar for the microbox to allow running the amc command without sudo.

BR
Gary

[Michele Lo Russo (lorumic)]

Hey Gary
That's not the point of the issue. The point is that the error message is wrong/misleading:

> But actually, this is not the reason why it failed. The "zip_archive_support" is present indeed:

> ubuntu@juju-4d0777-prod-anbox-cloud-webdemo-2:~$ sudo amc info | grep zip
- zip_archive_support

> So, this should probably give a different error? (Permission denied, I guess?)

[Simon Fels (morphis)]

You both are right :-)

The problem is in the way of how we check for an extension to be supported

func (c *clientImpl) HasExtension(name string) bool {
 if c.serviceStatus == nil {
  status, _, err := c.RetrieveServiceStatus()
  if err != nil {
   return false
  }
  c.serviceStatus = status
 }
        ....
}

RetrieveServiceStatus returns an error here but we hide that error. The reason it returns an error is that this is the first time the underlying HTTP client attempts to connect to the unix domain socket as Gary is describing. This can be fixed either by what Gary descries or by running amc as root as Michele did. The actual problem is though that we hide the connection error.

[Simon Fels (morphis)]

Fixed by https://github.com/canonical/ams/pull/77