Removing a container does not remove the underlying MAAS device representing the container unless the host is also removed.

[Dongwon Cho]

It does not remove the DHCP and DNS configurations on MAAS after juju removes LXD container(machine).

dpkg -l '*maas*' | cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===============================-====================================-============-=================================================
ii maas 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all "Metal as a Service" is a physical cloud and IPAM
ii maas-cli 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS client and command-line interface
un maas-cluster-controller <none> <none> (no description available)
ii maas-common 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS server common files
ii maas-dhcp 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS DHCP server
ii maas-dns 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS DNS server
ii maas-proxy 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS Caching Proxy
ii maas-rack-controller 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all Rack Controller for MAAS
ii maas-region-api 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all Region controller API service for MAAS
ii maas-region-controller 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all Region Controller for MAAS
un maas-region-controller-min <none> <none> (no description available)
un python-django-maas <none> <none> (no description available)
un python-maas-client <none> <none> (no description available)
un python-maas-provisioningserver <none> <none> (no description available)
ii python3-django-maas 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS server Django web framework (Python 3)
ii python3-maas-client 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS python API client (Python 3)
ii python3-maas-provisioningserver 2.0.0~beta5+bzr5026-0ubuntu1~xenial1 all MAAS server provisioning libraries (Python 3)

dpkg -l '*juju*' | cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-================================-============-============================================
ii juju 2.0-beta7-0ubuntu1~16.04.2~juju1 all next generation service orchestration system
ii juju-2.0 2.0-beta7-0ubuntu1~16.04.2~juju1 amd64 Juju is devops distilled - client
un juju-core <none> <none> (no description available)
un juju2 <none> <none> (no description available)

juju add-machine --constraints spaces=mgmt,^public-api,^tunnel,^storage lxd:0

juju show-machine
model: default
machines:
  "0":
    juju-status:
      current: started
      since: 25 May 2016 18:30:08+09:00
      version: 2.0-beta7
    dns-name: 10.192.228.52
    instance-id: 4y3h7p
    machine-status:
      current: running
      message: Deployed
      since: 25 May 2016 18:28:54+09:00
    series: xenial
    containers:
      0/lxd/3:
        juju-status:
          current: started
          since: 26 May 2016 11:19:10+09:00
          version: 2.0-beta7
        dns-name: 10.192.228.56
        instance-id: juju-machine-0-lxd-3
        machine-status:
          current: running
          message: Container started
          since: 26 May 2016 11:18:19+09:00
        series: xenial
    hardware: arch=amd64 cpu-cores=24 mem=128825M availability-zone=default

# On the physical node
sudo lxc list
+----------------------+---------+--------------------------------+------+------------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+----------------------+---------+--------------------------------+------+------------+-----------+
| juju-machine-0-lxd-3 | RUNNING | 10.192.228.56 (eth0) | | PERSISTENT | 0 |
| | | 192.168.101.56 (eth1) | | | |
| | | 192.168.102.56 (eth2) | | | |
| | | 10.192.229.56 (eth3) | | | |
+----------------------+---------+--------------------------------+------+------------+-----------+

juju remove-machine 0/lxd/3

juju show-machine
model: default
machines:
  "0":
    juju-status:
      current: started
      since: 25 May 2016 18:30:08+09:00
      version: 2.0-beta7
    dns-name: 10.192.228.52
    instance-id: 4y3h7p
    machine-status:
      current: running
      message: Deployed
      since: 25 May 2016 18:28:54+09:00
    series: xenial
    hardware: arch=amd64 cpu-cores=24 mem=128825M availability-zone=default

dig -x 10.192.228.56

; <<>> DiG 9.10.3-P4-Ubuntu <<>> -x 10.192.228.56
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59606
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;56.228.192.10.in-addr.arpa. IN PTR

;; ANSWER SECTION:
56.228.192.10.in-addr.arpa. 30 IN PTR unmordant-shandra.rnd.example.net.
56.228.192.10.in-addr.arpa. 30 IN PTR eth0.unmordant-shandra.rnd.example.net.

;; AUTHORITY SECTION:
228.192.10.in-addr.arpa. 30 IN NS rnd.example.net.

;; ADDITIONAL SECTION:
rnd.example.net. 30 IN A 10.192.228.2

;; Query time: 0 msec
;; SERVER: 10.192.228.2#53(10.192.228.2)
;; WHEN: Thu May 26 14:30:31 KST 2016
;; MSG SIZE rcvd: 154

# on the maas node

cat /etc/bind/maas/zone.rnd.example.net | grep 10.192.228.56
unmordant-shandra 30 IN A 10.192.228.56

cat /var/lib/maas/dhcpd.conf
...
...
host 00-16-3e-b0-82-7a {
   #
   # Node DHCP snippets
   #

   hardware ethernet 00:16:3e:b0:82:7a;
   fixed-address 10.192.228.56;
}

[Dimiter Naydenov (dimitern)]

Juju registers each container into MAAS as a multi-NIC device with a parent set to its host instance. It's up to MAAS to clean up those settings after the device representing the container is gone along with its host.

[Andres Rodriguez (andreserl)]

Can you list all the devices in MAAS, or go to the Machine details page where the container lives and see if the container is listed there? It may (or may not) be the case that Juju is not removing the containe, hence leaving the records there.

[Dimiter Naydenov (dimitern)]

Actually, looking at the commands mentioned in the description, I can confirm juju does not delete the device when the container is removed but the host remains.

[Christian Muirhead (2-xtian)]

PR to add ReleaseContainerAddresses to the Networking interface and the MAAS provider.
https://github.com/juju/juju/pull/5883

[Christian Muirhead (2-xtian)]

PR with state methods to be used by the machine removal worker: https://github.com/juju/juju/pull/5923

[Christian Muirhead (2-xtian)]

PR to expose the API for the machine undertaker: https://github.com/juju/juju/pull/5924

[Christian Muirhead (2-xtian)]

More PRs:

Simplify ReleaseContainerAddresses interface by requiring less information.
https://github.com/juju/juju/pull/5979

Expose machine.MarkForRemoval in provisioner API
https://github.com/juju/juju/pull/6042

Client side API for machine undertaker
https://github.com/juju/juju/pull/6053

Handle duplicate devices coming back from MAAS in ReleaseContainerAddresses
https://github.com/juju/juju/pull/6080

Enable multiple MAC addresses on test devices in gomaasapi
https://github.com/juju/gomaasapi/pull/56

Final one to add the machine undertaker worker (just finishing off the unit tests)
https://github.com/juju/juju/pull/6082

[Christian Muirhead (2-xtian)]

The unit tests are done on the last PR now, waiting for review.