De acordo com o site oficial do Docker , o docker pode ser instalado no Ubuntu 14.04, 16,04 e 16,10
OS requirements
To install Docker, you need the 64-bit version of one of these Ubuntu versions:
Yakkety 16.10
Xenial 16.04 (LTS)
Trusty 14.04 (LTS)
Docker CE is supported on both x86_64 and armhf architectures.
também o apt
falha por causa da wheezy
da sua distribuição do Ubuntu:
W: Conflicting distribution: http://download.mono-project.com wheezy/snapshots/3.12.0 InRelease (expected wheezy/snapshots but got wheezy)