Exim4の構築と特定ドメイン転送

📂 devbase/
├── 📄.env（必要なら作る）
├── 📄compose.override.yaml（必要なら作る）
├── 📄compose.yaml
└── 📂exim4/
    ├── 📄Dockerfile              # exim4を実行するコンテナ作成指示書
    ├── 📄entrypoint.sh           # コンテナ起動時に実行するヘルパースクリプト
    ├── 📄exim4.conf.localmacros  # exim4.conf生成用のdefine定義
    ├── 📄exim4.conf.template     # exim4.conf生成用のテンプレート
    └── 📄update-exim4.conf.conf  # exim4.conf生成用の変数定義

IGNORE_SMTP_LINE_LENGTH_LIMIT = 1

  @@ -322,6 +325,8 @@
  smtputf8_advertise_hosts = MAIN_SMTPUTF8_ADVERTISE_HOSTS
  .endif

+ ## NOTE: Customized by arkbig
+ # for performance
+ split_spool_directory = true
+ # no limit
+ smtp_accept_queue_per_connection = 0
+ # Listen
+ daemon_smtp_ports = 587
+
  #####################################################
  ### end main/02_exim4-config_options
  #####################################################

  @@ -1000,10 +1007,10 @@
  ######################################################################
  #     THE ORDER IN WHICH THE ROUTERS ARE DEFINED IS IMPORTANT!       #
  # An address is passed to each router in turn until it is accepted.  #
  ######################################################################

  begin routers

+ ## NOTE: Customized by arkbig
+ relay_routes:
+   debug_print = "R: relay_routes for $local_part@$domain"
+   driver = manualroute
+   domains = ! +local_domains
+   transport = remote_smtp
+   host_find_failed = ignore
+   same_domain_copy_routing = yes
+   route_data = ${lookup{$domain}partial-lsearch{/etc/exim4/relay_routes}}
+
  #####################################################
  ### end router/00_exim4-config_header
  #####################################################

dc_eximconfig_configtype='satellite'
dc_other_hostnames=''
dc_local_interfaces='0.0.0.0 ; ::0'
dc_readhost=''
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets='0.0.0.0/0'
dc_smarthost='' #これは $EXIM4_SMARTHOST で置き換えられる
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname=''
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'

FROM ubuntu

#---------------(1)--------------#
RUN set -eux \
 && apt-get update -y \
 && apt-get install -y --no-install-recommends \
        exim4 \
 && apt-get -y clean \
 && rm -rf /var/lib/apt/lists/*

#---------------(2)--------------#
# Debian-eximユーザー&グループが作られて、デーモン設定で起動するとそれが使われる
# ENV CONTAINER_UID=${CONTAINER_UID:-1000}
# ENV CONTAINER_GID=${CONTAINER_GID:-1000}
# RUN groupadd -g ${CONTAINER_GID} -o smtpstaff \
#  && useradd -g smtpstaff -m -o -u ${CONTAINER_UID} smtpstaff
# WORKDIR /home/smtpstaff/

#---------------(3)--------------#
# exim4.conf.templateは初期設定をコピーしてきて一部追記したものです。
# 追記箇所には"## NOTE: Custimezed by arkbig"の目印を書いてます。
COPY exim4.conf.localmacros exim4.conf.template update-exim4.conf.conf /etc/exim4/
COPY entrypoint.sh ./
RUN chmod +x ./entrypoint.sh

# 通常のメール転送先
ENV EXIM4_SMARTHOST=mailhog::1025
# 送信先が$EXIM4_RELAY_DOMAINなら$EXIM4_RELAY_ADDRへ転送する
# EXIM4_RELAY_{DOMAIN,ADDR}_1〜EXIM4_RELAY_{DOMAIN,ADDR}_Nまで連番で対応(抜け番があれば停止だが、"-"はスキップ)
ENV EXIM4_RELAY_DOMAIN=''
ENV EXIM4_RELAY_ADDR=''

EXPOSE 587

ENTRYPOINT ["./entrypoint.sh"]
# -bd   This option runs Exim as a daemon, awaiting incoming SMTP connections.
# -q<qflags><time>   When a time value is present, the -q option causes Exim to run as a daemon,
#                    starting a queue runner process at intervals specified by the given time value.
# -v   This option causes Exim to write information to the standard error stream, describing what it is doing.
CMD ["exim", "-bd", "-q10m", "-v"]

#!/usr/bin/env sh
#====================================================================
# begin of 定型文
# このスクリプトを厳格に実行
set -eu
# set -eux
# 環境に影響を受けないようにしておく
umask 0022
# PATH='/usr/bin:/bin'
IFS=$(printf ' \t\n_')
IFS=${IFS%_}
export IFS LC_ALL=C LANG=C PATH
# end of 定型文
#--------------------------------------------------------------------

#---------------(1)--------------#
# 専用のDebian-eximが使われる
# UID,GIDを合わせる
# uid=$(stat -c "%u" .)
# gid=$(stat -c "%g" .)
# ug_name=smtpstaff
# if [ "${CONTAINER_GID}" != "${gid}" ]; then
#     groupmod -g "${CONTAINER_GID}" -o "${ug_name}"
#     chgrp -R "${CONTAINER_GID}" .
# fi
# if [ "${CONTAINER_UID}" != "${uid}" ]; then
#     usermod -g "${ug_name}" -o -u "${CONTAINER_UID}" "${ug_name}"
# fi

#---------------(2)--------------#
# eximコマンドなら設定ファイルを編集する
if [ "${1}" = "exim" ]; then
    command_is_exim=true
elif [ "${1}" = "${1#-}" ]; then
    command_is_exim=false
else
    set -- exim "$@"
    command_is_exim=true
fi
if ${command_is_exim}; then
    # リレールートファイル作成
    echo '' >/etc/exim4/relay_routes
    skip_relay=false
    if [ -z "${EXIM4_RELAY_DOMAIN}" ]; then
        echo "EXIM4_RELAY_DOMAIN environment variable is empty so relay not added."
        skip_relay=true
    fi
    if [ -z "${EXIM4_RELAY_ADDR}" ]; then
        echo "EXIM4_RELAY_ADDR environment variable is empty so relay not added."
        skip_relay=true
    fi
    if ! ${skip_relay}; then
        echo "${EXIM4_RELAY_DOMAIN}: ${EXIM4_RELAY_ADDR}" >/etc/exim4/relay_routes
        sequence_number=1
        while true; do
            sequence_domain=$(eval "printf $(printf "%s" "\${EXIM4_RELAY_DOMAIN_${sequence_number}-\"\"}")")
            sequence_addr=$(eval "printf $(printf "%s" "\${EXIM4_RELAY_ADDR_${sequence_number}-\"\"}")")
            if [ -z "${sequence_domain}" ] || [ -z "${sequence_addr}" ]; then
                # 未定義なので終了
                break
            fi
            if [ "${sequence_domain}" = "-" ] || [ "${sequence_addr}" = "-" ]; then
                echo "skip sequence number ${sequence_number} because EXIM4_RELAY_DOMAIN_${sequence_number} or EXIM4_RELAY_ADDR_${sequence_number} is '-'."
            else
                echo "${sequence_domain}: ${sequence_addr}" >>/etc/exim4/relay_routes
            fi
            sequence_number=$((sequence_number + 1))
        done
    fi
    echo /etc/exim4/relay_routes
    cat /etc/exim4/relay_routes

    # 設定ファイル更新
    sed -i s/dc_smarthost=.*/dc_smarthost="${EXIM4_SMARTHOST}"/ /etc/exim4/update-exim4.conf.conf
    update-exim4.conf -v
fi

#---------------(3)--------------#
# 専用のDebian-eximが使われる
# if [ "$(id -u)" = "${CONTAINER_UID}" ]; then
#     exec "$@"
# else
#     # ユーザー変更してコマンド実行
#     exec /usr/sbin/gosu "${ug_name}" "$@"
# fi
exec "$@"

services:
  exim4:
    image: arkbig/exim4
    build:
      context: ./exim4
      args:
        no_proxy: ${no_proxy-}
        http_proxy: ${http_proxy-}
        https_proxy: ${https_proxy-}
    init: true
    restart: unless-stopped
    ports:
      - 127.0.0.1::587
    labels:
      - traefik.enable=true
      # Traefikにホスト名みてもらうためにSMTP over TLSにしたかったけど、exim4の設定がわからなかった
      # 複数SMTPサーバーが欲しくなったらstunnelというソフトを試すかな
      - traefik.tcp.routers.exim4-${COMPOSE_PROJECT_NAME:-devbase}.entrypoints=smtps
      - traefik.tcp.routers.exim4-${COMPOSE_PROJECT_NAME:-devbase}.rule=HostSNI(`*`)
      # - traefik.tcp.routers.exim4-${COMPOSE_PROJECT_NAME:-devbase}.rule=HostSNI(`exim4-${COMPOSE_PROJECT_NAME:-devbase}${DOMAIN:-.dev.test}`)
      # - traefik.tcp.routers.exim4-${COMPOSE_PROJECT_NAME:-devbase}.tls.passthrough=true

services:
  exim4:
    environment:
      # 通常のメール転送先(ポート番号指定する場合"::"コロンが２つなので注意)
      EXIM4_SMARTHOST: mailhog::1025
      # 宛先ドメインが指定したものだったら、専用の転送先に送る
      EXIM4_RELAY_DOMAIN:
      # 専用の転送先(これもポート番号指定する場合"::"コロンが２つなので注意)
      EXIM4_RELAY_ADDR:
      # 追加の変更ドメイン
      EXIM4_RELAY_DOMAIN_1:
      # 追加の変更IPアドレス
      EXIM4_RELAY_ADDR_1:
      # 以降も連番で指定可能
      # 空文字れつもしくは未定義に遭遇するとそこで終了
      # "-"ハイフンだけならその番号はスキップして、次の番号を処理

docker compose up -d exim4