docker-build.sh

#!/bin/bash
# vim: set ft=sh fdm=marker ts=2 sw=2 sts=2 tw=85 et:
set -eu

# ================================================
# Description: Enhanced docker build with some helper parameters, such as --env, --build-arg-file
#
# Usage:
#   docker-build [ -t tag_list ] [ -f Dockerfile ] [ ... ] [ --env <env_file> ] [ --build-arg-file <args_file> ]
#
# Last Modified: Sat May 14, 2022 14:46
# Author: Allex Wang ([email protected])
#
# GistID: 1ca3d49d817928ccab0a3317a18354c1
# GistURL: https://gist.github.com/1ca3d49d817928ccab0a3317a18354c1
# ================================================

PROG=$(basename "$0")
SH_DIR=$(cd -P -- "$(dirname -- "$(readlink -f "$0")")" && pwd -P)
WORKDIR=$(mktemp -d)
BUILDER_EXEC="docker buildx"

tag_list=
platform=linux/amd64,linux/arm64

env_file=
build_arg_list=()
docker_file=./Dockerfile
base_image=
patch_image=

# verbose for trace logs
verbose=

### Helper & ARGS {{{

die () {
  [ "${1-}" ] && echo >&2 "fatal: ${1}"
  exit "${2-1}"
}

log () {
  echo "${*}"
}

error () {
  echo >&2 "Error: ${*}"
}

show_usage () {
  cat <<-HELP
Enhanced docker build based on buildx, add some shortcut options, such as --env, --build-arg-file

Usage: ${PROG} [ -t tag_list ] [ -f Dockerfile ] [ ... ] [ --env <env_file> ] [ --build-arg-file <args_file> ]

Options:
      --env, --env-file <ENV_FILE>  Specify an alternate environment file 'ENV' instruction
      --build-arg-file <arg_file>   A file with k/v touples transform to docker build '--build-arg'
      --base-image <base_image>     The base image, only to be used when none Dockerfile
      --patch-image <patch_image>   The patch image to be apply to final Dockerfile
      --platform <platform_list>    Set platform, multiple platforms sep by comma[,] (default "linux/amd64,linux/arm64")
      -h                            Show this help info

For more options please refer to 'docker buildx build -h'
HELP
  exit 1
}

handle_exit () {
  local ec=$?
  if [ -d "$WORKDIR" ]; then rm -rf "$WORKDIR"; fi
  trap - INT TERM EXIT
  # declare -F on_exit, not avaiable in alipine/sh
  if type on_exit >/dev/null 2>&1; then on_exit; fi
  exit $ec
}
trap handle_exit 0 1 2 3 6 15

if [ $# -eq 0 ]; then
  show_usage
fi

args=()

while [ $# -gt 0 ]; do
  OPT=$1
  [ "$OPT" = "--" ] && break
  [ "$OPT" = "${OPT##-*}" ] && {
    args+=("$OPT")
    shift
    continue
  }
  if [ "${OPT##=*}" = "$OPT" ]; then
    OPTARG="${2-}"
    if [ "${OPTARG##-*}" = "${OPTARG}" ]; then
      shift
    else
      OPTARG=
    fi
  else
    OPT=$(echo "$1" | awk -F= '{print $1}')
    OPTARG=$(echo "$1" | awk -F= '{print $2}')
  fi
  case $OPT in
    # builtin parameters
    -t | --tag)
      tag_list="${OPTARG}"
      ;;
    -f)
      docker_file=${OPTARG}
      ;;
    --platform)
      platform=${OPTARG}
      ;;

    # enhanced parameters
    --base-image)
      base_image=${OPTARG}
      ;;
    --patch-image)
      patch_image=${OPTARG}
      ;;
    --env | --env-file)
      env_file=${OPTARG}
      ;;
    --build-arg)
      build_arg_list+=(--build-arg "${OPTARG}")
      ;;
    --build-arg-file)
      [ -n "$OPTARG" ] || die "Invalid parameter \"$OPT <arg_file>\" value"
      while read -r line; do build_arg_list+=(--build-arg "\"${line%=*}=${line#*=}\""); done < "$OPTARG"
      ;;
    --builder)
      [ -n "$OPTARG" ] && BUILDER_EXEC=$OPTARG
      ;;

    # misc
    -x | --debug) verbose=1 ;;
    -h | --help) show_usage ;;
    -*)
      args+=("$OPT")
      [ "$OPTARG" ] && args+=("\"$OPTARG\"")
      ;;
  esac
  [ $# -gt 0 ] && shift
done

[ -n "$tag_list" ] || die "Invalid parameter \"-t <tag_list>\" value"

### }}}

gen_dockerfile () {
  log "Build Dockerfile ..."

  #1 copy supplied Dockerfile if exists.
  #2 build from base image if not #1
  #3 add patch image stuffs by `patch_image`

  docker_file_spec=
  if [ -f "$docker_file" ]; then
    docker_file_spec=$(cat "${docker_file}")
  elif [ "$base_image" ]; then
    docker_file_spec="FROM $base_image"
  fi

  # transform .env file
  env_spec=
  env_patch=
  [ -f "$env_file" ] && {
    env_spec=$(sed -e '/^#/d;/^\s*$/d' "$env_file" | tr '\n' ' ')
  }

  if [ "$patch_image" ]; then
    log "Extract patch image ENV... ($patch_image)"
    docker pull "${patch_image}" > /dev/null
    env_patch="$(docker inspect "${patch_image}" --format='{{range $k, $v := .Config.Env}}{{$v}}{{"\n"}}{{end}}'|while read -r line; do if [ -n "$line" ]; then echo "${line%=*}=\"${line#*=}\""; fi; done |tr '\n' ' ')"
    docker rmi -f "${patch_image}" >/dev/null
    log "Parse image ENV success."
  fi

  tmp="$(cat <<-__DOCKERFILE__ |sed '{/^$/d}'
		${patch_image:+FROM ${patch_image}}
		$docker_file_spec
		${env_patch:+ENV $env_patch}
		${env_spec:+ENV $env_spec}
		${patch_image:+COPY --from=0 / /}
	__DOCKERFILE__
  )"

  # evaluate environs
  vars="$(envsubst -v "$tmp" | sort | uniq | awk '{if(ENVIRON[$0])print "${"$0"}"}')"
  echo "$tmp" | envsubst "$vars" > "$WORKDIR/Dockerfile"

  echo "-----------"
  cat "$WORKDIR/Dockerfile"
  echo "-----------"
  echo
}

build () {
  log "Start to build docker image ..."

  local specfile=$WORKDIR/Dockerfile

  # fix buildx args
  local platform=${platform}
  [ "$platform" ] && args+=("--platform" "$platform")

  export BUILDX_NO_DEFAULT_LOAD=false
  eval "(${verbose:+set -x;}${BUILDER_EXEC} build -t $tag_list ${build_arg_list:+${build_arg_list[@]}} -f $specfile ${args:+${args[@]}})"

  log "Build done${tag_list:+ => ${tag_list}}"
}

gen_dockerfile \
  && build "$@"