Ensure that "mail from" works on RHEL/CentOS

[dnsmichi]

Change from #5170 (comment) doesn't seem to work reliably.

#5170 (comment) tell that tests happened, but I doubt they were successful.

Before releasing 2.7 we should ensure to have this working properly.

[dnsmichi]

Discussed it offline. Unfortunately tests did not target the "mail from" functionality. So we need to fix that accordingly.

[dnsmichi]

Analysis

mail on Linux/Unix is a PITA.

Now for my findings:

• Debian's default supports -a (from mailutils)

• RHEL uses -a for attachments, but insists on -r (which is the default for "mailx")

• Unix might have or not have it

• -a expects From: Firstname Lastname <mail@foo.com>

• -r expects a single string with an email address, or "Firstname Lastname mail@foo.com".

The only thing I see here, to make it at least work on the base distributions we support:

• check for /etc/debian-version and use mailutils
• use mailx otherwise (on rhel it is called bsd-mailx, so I would believe that *BSD has it too)
• add the right param and format
• add documentation for the user with the encouragement to modify the script for their own mail binary with different parameters.

If anyone comes up with a proper bash script or patch, feel free. But not for v2.7 anymore.

Misc

The script wasn't properly tested on Ubuntu/Debian. There must have been a warning at least for /bin/sh not being bash but dash. Needs to be changed too.

./mail-service-notification.sh: 135: [: unexpected operator

Tests

CentOS 7

[root@icinga2 ~]# cat /etc/os-release
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"

[root@icinga2 ~]# ./mail-service-notification.sh -4 1.2.3.4 -d 1234 -e bumsti -l foohost -n schnurzi -u puh -o "i hate different mail binaries and different behaviours" -r "michael.friedrich@netways.de" -s 2 -t PROBLEM -f "Michael Friedrich <michael.friedrich@icinga.com>"

From: Michael Friedrich <michael.friedrich@icinga.com>
Subject: [PROBLEM] puh on schnurzi is 2!
Date: 16. June 2017 at 20:40:40 GMT+2
To: michael.friedrich@netways.de


***** Icinga 2 Service Monitoring on foohost *****

==> puh on schnurzi is 2! <==

Info:    i hate different mail binaries and different behaviours

When:    1234
Service: bumsti (Display Name: "puh")
Host:    foohost (Display Name: "schnurzi")
IPv4:    1.2.3.4

Ubuntu 16.04 LTS

root@vagrant:~# cat /etc/os-release
NAME="Ubuntu"
VERSION="16.04.2 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.2 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial

root@vagrant:~# ./mail-service-notification.sh -4 1.2.3.4 -d 1234 -e bumsti -l foohost -n schnurzi -u puh -o "i hate different mail binaries and different behaviours" -r "michael.friedrich@netways.de" -s 2 -t PROBLEM -f "Michael Friedrich <michael.friedrich@icinga.com>"

From: Michael Friedrich <michael.friedrich@icinga.com>
Subject: [PROBLEM] puh on schnurzi is 2!
Date: 16. June 2017 at 20:35:33 GMT+2
To: <michael.friedrich@netways.de>


***** Icinga 2 Service Monitoring on foohost *****

==> puh on schnurzi is 2! <==

Info:    i hate different mail binaries and different behaviours

When:    1234
Service: bumsti (Display Name: "puh")
Host:    foohost (Display Name: "schnurzi")
IPv4:    1.2.3.4