portfolio/labs/linux/setup/scripts/04-docker.sh

#!/usr/bin/env bash
set -o errexit
set -o nounset
set -o pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=00-platform-guard.inc
source "$SCRIPT_DIR/00-platform-guard.inc"
SOURCE_CONFIG="$SCRIPT_DIR/../files/docker/daemon.json"
DOCKER_CONFIG="/etc/docker/daemon.json"
temporary_files=()

cleanup() {
  local path

  for path in "${temporary_files[@]}"; do
    rm -f "$path"
  done
}

trap cleanup EXIT

backup_file() {
  local path="$1"
  local backup

  backup="${path}.$(date '+%Y%m%d-%H%M%S').bak"
  install -m 0644 "$path" "$backup"
  printf 'INFO: backed up %s to %s\n' "$path" "$backup"
}

if ((EUID != 0)); then
  printf 'CRITICAL: Docker setup must run as root\n' >&2
  exit 2
fi
require_supported_ubuntu
for command_name in apt-get apt-cache; do
  if ! command -v "$command_name" >/dev/null 2>&1; then
    printf 'CRITICAL: required command is missing: %s\n' "$command_name" >&2
    exit 2
  fi
done

apt-get update
DEBIAN_FRONTEND=noninteractive apt-get install -y ca-certificates curl gnupg jq

if apt-cache show docker.io >/dev/null 2>&1; then
  packages=(docker.io)
  if apt-cache show docker-compose-v2 >/dev/null 2>&1; then
    packages+=(docker-compose-v2)
  else
    printf 'WARNING: docker-compose-v2 is unavailable from Ubuntu repositories\n'
  fi
else
  printf 'WARNING: docker.io is unavailable; configuring Docker official repository\n'
  install -d -m 0755 /etc/apt/keyrings
  tmp_key="$(mktemp)"
  temporary_files+=("$tmp_key")
  curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
    | gpg --dearmor --yes -o "$tmp_key"
  if [[ ! -f /etc/apt/keyrings/docker.gpg ]] || \
    ! cmp -s "$tmp_key" /etc/apt/keyrings/docker.gpg; then
    if [[ -f /etc/apt/keyrings/docker.gpg ]]; then
      backup_file /etc/apt/keyrings/docker.gpg
    fi
    install -m 0644 "$tmp_key" /etc/apt/keyrings/docker.gpg
  fi

  # shellcheck disable=SC1091
  source /etc/os-release
  architecture="$(dpkg --print-architecture)"
  tmp_repository="$(mktemp)"
  temporary_files+=("$tmp_repository")
  printf 'deb [arch=%s signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu %s stable\n' \
    "$architecture" "${VERSION_CODENAME:?}" \
    >"$tmp_repository"
  if [[ ! -f /etc/apt/sources.list.d/docker.list ]] || \
    ! cmp -s "$tmp_repository" /etc/apt/sources.list.d/docker.list; then
    if [[ -f /etc/apt/sources.list.d/docker.list ]]; then
      backup_file /etc/apt/sources.list.d/docker.list
    fi
    install -m 0644 "$tmp_repository" /etc/apt/sources.list.d/docker.list
  fi
  apt-get update
  packages=(docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin)
fi

DEBIAN_FRONTEND=noninteractive apt-get install -y "${packages[@]}"
install -d -m 0755 /etc/docker

if [[ ! -r "$SOURCE_CONFIG" ]]; then
  printf 'CRITICAL: Docker configuration template is missing: %s\n' "$SOURCE_CONFIG" >&2
  exit 2
fi
jq empty "$SOURCE_CONFIG"

tmp_config="$(mktemp)"
temporary_files+=("$tmp_config")
if [[ -f "$DOCKER_CONFIG" ]]; then
  if ! jq empty "$DOCKER_CONFIG" >/dev/null 2>&1; then
    printf 'CRITICAL: %s is invalid JSON; refusing to overwrite it\n' "$DOCKER_CONFIG" >&2
    exit 1
  fi
  jq '. + {
    "log-driver": "json-file",
    "log-opts": ((."log-opts" // {}) + {"max-size": "50m", "max-file": "5"})
  }' "$DOCKER_CONFIG" >"$tmp_config"
else
  install -m 0644 "$SOURCE_CONFIG" "$tmp_config"
fi
jq empty "$tmp_config"

config_changed=0
if [[ ! -f "$DOCKER_CONFIG" ]] || ! cmp -s "$tmp_config" "$DOCKER_CONFIG"; then
  if [[ -f "$DOCKER_CONFIG" ]]; then
    backup_file "$DOCKER_CONFIG"
  fi
  install -m 0644 "$tmp_config" "$DOCKER_CONFIG"
  config_changed=1
  printf 'OK: installed Docker daemon log limits\n'
else
  printf 'OK: Docker daemon configuration is already current\n'
fi

systemctl enable --now docker
if ((config_changed == 1)); then
  systemctl restart docker
fi

docker version
if docker compose version >/dev/null 2>&1; then
  docker compose version
else
  printf 'WARNING: Docker Compose v2 is unavailable\n'
fi
printf 'OK: Docker setup completed\n'