lxc-new-unprivileged

#!/bin/bash

# A simple script to create na uprivileged LXC container based on current LXC
# host distribution, release and architecture. The script uses the
# 'lxc-hwaddr-static' and 'lxc-prepare-ssh' commands to further configure the
# created LXC container.

# Usage: lxc-new-unprivileged <container> [config-file]


set -o nounset -o pipefail -o errexit

readonly SCRIPT="$(basename "${0}")"
readonly CONTAINER="${1:-}"
readonly CONFIG_FILE="${2:-/etc/lxc/unprivileged.conf}"

readonly DISTRIBUTION="$(lsb_release -i | awk '{print $NF}' | tr '[:upper:]' '[:lower:]')"
readonly RELEASE="$(lsb_release -c | awk '{print $NF}' | tr '[:upper:]' '[:lower:]')"
readonly ARCHITECTURE="$(dpkg --print-architecture)"

container_exists () {
    local container
    container="${1}"

    if lxc-ls -1 | grep -q -E "^${container}$" ; then
        return 0
    else
        return 1
    fi
}

print_usage () {
    cat <<EOF
${SCRIPT}: create new unprivileged LXC container based on LXC host

Usage: ${SCRIPT} <container-name> [config-file]
EOF
}

error_msg () {
    printf "%s\n" "${*}" >&2
}

main () {
    local container
    container="${CONTAINER}"

    local config_file
    config_file="${CONFIG_FILE}"

    local distribution
    distribution="${DISTRIBUTION}"

    local release
    release="${RELEASE}"

    local architecture
    architecture="${ARCHITECTURE}"

    if [ -n "${container}" ] ; then
        if ! container_exists "${container}" ; then

            printf "Container '%s' doesn't exist, creating...\n" "${container}"

            lxc-create --name "${container}" \
                       --config "${config_file}" \
                       --template "download" \
                       -- --dist "${distribution}" \
                          --release "${release}" \
                          --arch "${architecture}"

            lxc-hwaddr-static "${container}"
            lxc-start -n "${container}" -d
            lxc-wait -n "${container}" -s RUNNING

            # During container creation, a static hostname is added into
            # '/etc/hosts' which breaks proper DNS domain resolution of the
            # container. Because we are using DHCP/DNS server to manage
            # containers, remove the static host entry to fix the issue.
            if lxc-attach -n "${container}" -- grep -q '127.0.1.1' /etc/hosts ; then
                printf "Removing static host entry from /etc/hosts...\n"
                lxc-attach -n "${container}" -- sed -i "/127\.0\.1\.1/d" /etc/hosts > /dev/null
            fi

            until lxc-prepare-ssh "${container}" ; do
                ((c++)) && ((c==4)) && break
                printf "Waiting for network inside container to settle...\n"
                sleep 5
            done

        else
            error_msg "Error: container '${container}' already exists"
            return 1
        fi
    else
        print_usage
        return 1
    fi
}

main