Não tenho certeza se ele está correlacionado, mas acabei de atualizar para o MAAS 1.9 e, desde os dias de reboque, o apt-get update falha em todos os nós MAAS. Eu tenho outros nós não MAAS e eles funcionam bem, embora usem um repositório local em vez de archive.ubuntu.com.
Abaixo da saída do apt-get update.
ubuntu@machine:~$ sudo apt-get update
Ign http://archive.ubuntu.com trusty InRelease
Ign http://archive.ubuntu.com trusty-updates InRelease
Ign http://archive.ubuntu.com trusty-security InRelease
Ign http://archive.ubuntu.com trusty Release.gpg
Ign http://archive.ubuntu.com trusty-updates Release.gpg
Ign http://archive.ubuntu.com trusty-security Release.gpg
Ign http://archive.ubuntu.com trusty Release
Ign http://archive.ubuntu.com trusty-updates Release
Ign http://archive.ubuntu.com trusty-security Release
Ign http://archive.ubuntu.com trusty/main amd64 Packages/DiffIndex
Hit http://qgis.org trusty InRelease
Ign http://archive.ubuntu.com trusty/restricted amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty/universe amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty/multiverse amd64 Packages/DiffIndex
Get:1 http://archive.ubuntu.com trusty/main Translation-en [762 kB]
Hit http://qgis.org trusty/main Sources
Hit http://qgis.org trusty/main amd64 Packages
Get:2 http://archive.ubuntu.com trusty/multiverse Translation-en [102 kB]
Get:3 http://archive.ubuntu.com trusty/restricted Translation-en [3,457 B]
Get:4 http://archive.ubuntu.com trusty/universe Translation-en [4,089 kB]
Ign http://qgis.org trusty/main Translation-en_US
Ign http://qgis.org trusty/main Translation-en
Ign http://archive.ubuntu.com trusty-updates/main amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-updates/restricted amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-updates/universe amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-updates/multiverse amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-security/main amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-security/restricted amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-security/universe amd64 Packages/DiffIndex
Ign http://archive.ubuntu.com trusty-security/multiverse amd64 Packages/DiffIndex
Get:5 http://archive.ubuntu.com trusty-updates/main Translation-en [422 kB]
Get:6 http://archive.ubuntu.com trusty-updates/multiverse Translation-en [6,863 B]
Get:7 http://archive.ubuntu.com trusty-updates/universe Translation-en [222 kB]
Ign http://archive.ubuntu.com trusty/main Translation-en_US
Ign http://archive.ubuntu.com trusty/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/main Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/restricted Translation-en
Ign http://archive.ubuntu.com trusty-updates/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-security/main Translation-en_US
Ign http://archive.ubuntu.com trusty-security/main Translation-en
Ign http://archive.ubuntu.com trusty-security/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-security/multiverse Translation-en
Ign http://archive.ubuntu.com trusty-security/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-security/restricted Translation-en
Ign http://archive.ubuntu.com trusty-security/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-security/universe Translation-en
Err http://archive.ubuntu.com trusty/main amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty/restricted amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty/universe amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty/multiverse amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-updates/main amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-updates/restricted amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-updates/universe amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-updates/multiverse amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-security/main amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-security/restricted amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-security/universe amd64 Packages 503 Service Unavailable
Err http://archive.ubuntu.com trusty-security/multiverse amd64 Packages 503 Service Unavailable
Fetched 5,607 kB in 20s (274 kB/s)
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty/main/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty/restricted/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty/universe/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty/multiverse/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-updates/main/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-updates/restricted/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-updates/universe/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-updates/multiverse/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-security/main/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-security/restricted/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-security/universe/binary-amd64/Packages 503 Service Unavailable
W: Failed to fetch http://archive.ubuntu.com//ubuntu/dists/trusty-security/multiverse/binary-amd64/Packages 503 Service Unavailable
E: Some index files failed to download. They have been ignored, or old ones used instead.
Como se pode ver, parece haver um problema no ultimo url referente ao "//", que vem do /etc/apt/sources.list, mas isso não foi um problema antes, pois as atualizações funcionaram bem e terceiros ppa install funcionou também sem problema.
Abaixo do arquivo sources.list.
deb http://archive.ubuntu.com//ubuntu trusty main restricted universe multiverse
deb http://archive.ubuntu.com//ubuntu trusty-updates main restricted universe multiverse
deb http://archive.ubuntu.com//ubuntu trusty-security main restricted universe multiverse
deb http://qgis.org/debian trusty main
deb-src http://qgis.org/debian trusty main
Note que eu sou capaz de ver a url que falha com wget, exceto que com "Packages.gz" funciona, mas não com "Packages" (e funciona com //).
Qualquer ajuda seria apreciada.
Aparentemente, algo foi quebrado com a atualização e proxy do MAAS 1.9 para o apt. Comentando a linha de configurações de proxy em 90curtin-aptproxy fez o truque.
ubuntu@machine:/etc/apt/apt.conf.d$ more 90curtin-aptproxy
#Acquire::HTTP::Proxy "http://<MAAS_IP>:8000/";
Agora posso executar o apt-get update e atualizar os nós MAAS conforme necessário. Provavelmente um bug que uma configuração não mudou no MAAS e é o padrão.