Let's Encryptの cronによる実行が動かなくなった時の対策

certbot (Let's Encrypt)を Amazon Linuxにインストールの後日談。
OSはAmazon linux。

cronの結果がメールで送られてきた。

Checking for new version...
Upgrading certbot-auto 0.6.0 to 0.7.0...
Replacing certbot-auto...
Creating virtual environment...
./certbot/certbot-auto: line 530: virtualenv: command not found

↓
cronを再実行してみる。

WARNING: Amazon Linux support is very experimental at present...
if you would like to work on improving it, please ensure you have backups
and then run this script again with the --debug flag!

↓
言われた通りにコマンドを変更。

./certbot/certbot-auto renew --debug && sudo service httpd reload

再実行。

Bootstrapping dependencies via Amazon Linux...
yum is /usr/bin/yum
Loaded plugins: priorities, update-motd, upgrade-helper
Package gcc-4.8.3-3.20.amzn1.noarch already installed and latest version
Package dialog-1.1-9.20080819.1.5.amzn1.x86_64 already installed and latest version
Package augeas-libs-1.0.0-5.7.amzn1.x86_64 already installed and latest version
Package 1:openssl-1.0.1k-14.91.amzn1.x86_64 already installed and latest version
Package 1:openssl-devel-1.0.1k-14.91.amzn1.x86_64 already installed and latest version
Package libffi-devel-3.0.13-11.4.amzn1.x86_64 already installed and latest version
Package system-rpm-config-9.0.3-42.27.amzn1.noarch already installed and latest version
Package ca-certificates-2015.2.6-65.0.1.15.amzn1.noarch already installed and latest version
Package python27-2.7.10-4.120.amzn1.x86_64 already installed and latest version
Package python27-devel-2.7.10-4.120.amzn1.x86_64 already installed and latest version
Resolving Dependencies
--> Running transaction check
---> Package python27-pip.noarch 0:6.1.1-1.21.amzn1 will be installed
---> Package python27-tools.x86_64 0:2.7.10-4.120.amzn1 will be installed
---> Package python27-virtualenv.noarch 0:12.0.7-1.12.amzn1 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
 Package                 Arch       Version                 Repository     Size
================================================================================
Installing:
 python27-pip            noarch     6.1.1-1.21.amzn1        amzn-main     1.9 M
 python27-tools          x86_64     2.7.10-4.120.amzn1      amzn-main     706 k
 python27-virtualenv     noarch     12.0.7-1.12.amzn1       amzn-main     2.0 M
Transaction Summary
================================================================================
Install  3 Packages
Total download size: 4.6 M
Installed size: 11 M
Is this ok [y/d/N]: Exiting on user command
Your transaction was saved, rerun it with:
 yum load-transaction /tmp/yum_save_tx.2016-06-22.11-17.hYs7z_.yumtx
Could not install OS dependencies. Aborting bootstrap!

↓
cronでなく手動で実行し、パッケージをインストール

./certbot/certbot-auto renew --debug

↓
正常終了。
以降はcronでも"--debug"無しでも大丈夫になったが、"--debug"を付けておいた方が無難？