Using MAAS 2.1.2 (bzr 5555) and Juju 2.0.1:
I tried deploying 6 units of Ubuntu, each with a LXD container also running Ubuntu. Two of the machines failed to deploy (because of bug 1635560 but unimportant - just note that it's transient). When I tried to retry-provisioning nothing happened.
⟫ juju status
Model Controller Cloud/Region Version
default hare hare 2.0.1
App Version Status Scale Charm Store Rev OS Notes
ubuntu 16.04 waiting 8/12 ubuntu jujucharms 8 ubuntu
Unit Workload Agent Machine Public address Ports Message
ubuntu/0 active idle 0 10.2.0.54 ready
ubuntu/1* active idle 1 10.2.0.55 ready
ubuntu/2 active idle 2 10.2.0.56 ready
ubuntu/3 active idle 3 10.2.0.57 ready
ubuntu/4 waiting allocating 4 10.2.0.52 waiting for machine
ubuntu/5 waiting allocating 5 10.2.0.53 waiting for machine
ubuntu/6 active idle 0/lxd/0 10.2.0.61 ready
ubuntu/7 active idle 1/lxd/0 10.2.0.58 ready
ubuntu/8 active idle 2/lxd/0 10.2.0.60 ready
ubuntu/9 active idle 3/lxd/0 10.2.0.59 ready
ubuntu/10 waiting allocating 4/lxd/0 waiting for machine
ubuntu/11 waiting allocating 5/lxd/0 waiting for machine
Machine State DNS Inst id Series AZ
0 started 10.2.0.54 4y3hbp xenial Raphael
0/lxd/0 started 10.2.0.61 juju-d0b4d0-0-lxd-0 xenial
1 started 10.2.0.55 4y3hbq xenial default
1/lxd/0 started 10.2.0.58 juju-d0b4d0-1-lxd-0 xenial
2 started 10.2.0.56 abnf8x xenial Raphael
2/lxd/0 started 10.2.0.60 juju-d0b4d0-2-lxd-0 xenial
3 started 10.2.0.57 x7nfeg xenial default
3/lxd/0 started 10.2.0.59 juju-d0b4d0-3-lxd-0 xenial
4 down 10.2.0.52 4y3h7x xenial Raphael
4/lxd/0 pending pending xenial
5 down 10.2.0.53 4y3h7y xenial default
5/lxd/0 pending pending xenial
⟫ juju retry-provisioning 5 --debug
18:07:46 INFO juju.cmd supercommand.go:63 running juju [2.0.1 gc go1.6.2]
18:07:46 DEBUG juju.cmd supercommand.go:64 args: []string{"juju", "retry-provisioning", "5", "--debug"}
18:07:46 INFO juju.juju api.go:72 connecting to API addresses: [10.2.0.51:17070]
18:07:46 INFO juju.api apiclient.go:530 dialing "wss://10.2.0.51:17070/model/5a113b53-5bf4-42cd-8d8f-4dd933d0b4d0/api"
18:07:47 INFO juju.api apiclient.go:466 connection established to "wss://10.2.0.51:17070/model/5a113b53-5bf4-42cd-8d8f-4dd933d0b4d0/api"
18:07:47 DEBUG juju.juju api.go:263 API hostnames unchanged - not resolving
18:07:47 INFO cmd supercommand.go:465 command finished
Why can't juju automatically retry-provisioning? It knows many cases where provisioning failed. juju is retrying hooks now; users rarely need to retry.