Install and configure Docker (+compose) on Ubuntu

!docker-install.md

My current take on how to install and configure Docker (+compose) on a standalone Ubuntu system.

Please read the content for more information.

content.md

Docker installation and configuration

This installs Docker from their Ubuntu repository and configures it with user namespace remapping.

Run this:

# { (. <(cat << "#EOF" # copy from after the first #
set -eux

## installation
apt-get install -y apt-transport-https ca-certificates curl gnupg-agent software-properties-common jq
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
sudo add-apt-repository "deb [arch=$(dpkg --print-architecture)] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" # runs apt-get update
apt install -y docker-ce docker-compose

## prepare user namespace remapping
if ! id -u dockremap ; then
    adduser --system dockremap --gecos '' --group --disabled-login --no-create-home
    printf '%s\n' 'dockremap:1000000:65536' >> /etc/subuid
    printf '%s\n' 'dockremap:1000000:65536' >> /etc/subgid
fi

## set sensible defaults
# (incl. user namespace remapping), but keep any values already set
config=$(jq '{
    "userns-remap": "dockremap:dockremap",
    "icc": false,
    "live-restore": true,
    "userland-proxy": false,
    "no-new-privileges": true,
    "log-driver": "json-file",
    "log-opts": { "max-size": "10m", "max-file": "3", },
} + .' <<< $(cat /etc/docker/daemon.json || echo '{}'))
cat <<< "${config}" > /etc/docker/daemon.json
service docker stop; service docker start # just a reload didn't work
# 'no-new-privileges' could be problematic with images that require setuid binaries

#EOF
)); }

Next steps

• Make sure the range added for dockremap in /etc/sub{u,g}id does not overlap with previously used UID/GIDs (e.g. in cat /etc/passwd).
• Add non-root users to the docker group: ( user=setup; if ! id -u $user ; then adduser $user --gecos "" --disabled-password ; fi; usermod -aG docker $user ).
• Prepare the new docker host to host web apps