定期的にLet's Encrypt証明書を更新してSlackでアナウンス ref: https://qiita.com/leedohyung-dba/items/947185ab37818b66bacd

file0.txt

0 4 1 1,3,5,7,9,11 * root /usr/bin/systemctl stop httpd.service && /usr/bin/certbot renew --force-renew --quiet --post-hook "/usr/bin/systemctl start httpd.service"

file2.txt

0 4 1 1,3,5,7,9,11 * root /bin/sh /run/ssl_certificate_renew.sh

ssl_certificate_renew.sh

#!/bin/bash

# WebHookのURL
WEBHOOK_URL='https://hooks.slack.com/services/***************************'

# メッセージを一時保存する場所
MESSAGEFILE=$(mktemp -t ssl-certificate-notice-XXXX)

# 送信先のチャンネル
CHANNEL=${CHANNEL:-'#lee_test'}

# 終了時に削除
trap "rm ${MESSAGEFILE}" 0


send_notice_to_slack_renew_start () {
    # 見出し
    hd=${HEAD:-"start to ssl certificate renew.\n"}

    # json形式に整形
    payload="payload={
        \"channel\": \"${CHANNEL}\",
        \"text\": \"${hd}\"
    }"

    curl -s -S -X POST --data-urlencode "${payload}" ${WEBHOOK_URL} > /dev/null
}

send_notice_to_slack_renew_success () {
    # 見出し
    hd=${HEAD:-"ssl certificate renew success.\n"}
    # 絵文字
    emoji=${EMOJI:-':carlton:'}

    # json形式に整形
    payload="payload={
        \"channel\": \"${CHANNEL}\",
        \"icon_emoji\": \"${emoji}\",
        \"text\": \"${hd}\"
    }"

    curl -s -S -X POST --data-urlencode "${payload}" ${WEBHOOK_URL} > /dev/null
}

send_notice_to_slack_renew_fail () {
    # 改行処理
    cat ${MESSAGEFILE} | tr '\n' '\\' | sed 's/\\/\\n/g' > ${MESSAGEFILE}

    # 絵文字
    emoji=${EMOJI:-':aaw_yeah:'}
    # 見出し
    hd=${HEAD:-"<!here>ssl certificate renew fail.\n"}
    # メッセージをシンタックスハイライト付きで取得
    msg='```'`cat ${MESSAGEFILE}`'```'

    # json形式に整形
    payload="payload={
        \"channel\": \"${CHANNEL}\",
        \"icon_emoji\": \"${emoji}\",
        \"text\": \"${hd}${msg}\"
    }"

    curl -s -S -X POST --data-urlencode "${payload}" ${WEBHOOK_URL} > /dev/null
}

send_notice_to_slack_renew_start

/usr/bin/systemctl stop httpd.service
/usr/bin/certbot renew --force-renew --quiet 2> ${MESSAGEFILE}
RENEW_RESULT=$?
/usr/bin/systemctl start httpd.service

if [ ${RENEW_RESULT} -eq 0 ]; then
  send_notice_to_slack_renew_success
else
  send_notice_to_slack_renew_fail
fi