feat(inputs): Add LDAP input plugin supporting OpenLDAP and 389ds

[srebhan]

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

This is a now plugin that superseeds the OpenLDAP plugin. It generalizes the metric gathering and adds support for the 389ds directory server.

[powersj]

Thank you for this as well!

One typo in sample config, I think?

Can you highlight what a user, using the existing openldap would need to do to switch over? Other than the switch from a host/port to server parameter, is there anything else? Are the metrics identical otherwise?

[dburton-influxdata]

Would the customer be able to just download the Nightly builds published on our Release site to test? - https://portal.influxdata.com/downloads/

They are willing to test and I am working to see how I can get them the test build.

[powersj]

@dburton-influxdata there are artifacts available in the comment above by the telegraf-tiger (direct link). If they click the little box icon it will expand to provide even more downloads.

I would prefer that we get confirmation from the customer before landing this in master.

Thanks!

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_amd64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

☺️ This pull request doesn't significantly change the Telegraf binary size (less than 1%)

📦 Click here to get additional PR build artifacts

Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[powersj]

Approving since I'll be out, but please wait to land until we hear back from a user.

[srebhan]

Merging after positive feedback from the user...