From da2d73b676f1257963705a487215739a62edce83 Mon Sep 17 00:00:00 2001
From: "Dustin C. Hatch" <dustin@hatch.name>
Date: Wed, 18 Jul 2018 20:27:05 -0500
Subject: [PATCH] roles/dhcpcd: Disable device management module

Today I realized that `dhcpcd` has been logging several hundred thousand
of these messages every second:

    libudev: received NULL device

This was causing both `dhcpcd` and `systemd-journald` to consume 100%
CPU.

I am not entirely sure what a "device management" module is in the
context of `dhcpcd`, but it does not seem to be required. Setting the
`nodev` option in `dhcpcd.conf` suppresses the messages, and seems to
have no effect on the operation of the daemon.
---
 roles/dhcpcd/defaults/main.yml        | 1 +
 roles/dhcpcd/templates/dhcpcd.conf.j2 | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/roles/dhcpcd/defaults/main.yml b/roles/dhcpcd/defaults/main.yml
index a6264b6..7f5b223 100644
--- a/roles/dhcpcd/defaults/main.yml
+++ b/roles/dhcpcd/defaults/main.yml
@@ -11,3 +11,4 @@ dhcpcd_noipv4ll: false
 dhcpcd_noipv4: false
 dhcpcd_noipv6rs: false
 dhcpcd_interfaces: []
+dhcpcd_nodev: false
diff --git a/roles/dhcpcd/templates/dhcpcd.conf.j2 b/roles/dhcpcd/templates/dhcpcd.conf.j2
index ee26d45..c31497b 100644
--- a/roles/dhcpcd/templates/dhcpcd.conf.j2
+++ b/roles/dhcpcd/templates/dhcpcd.conf.j2
@@ -1,5 +1,10 @@
 # A sample configuration for dhcpcd.
 # See dhcpcd.conf(5) for details.
+{% if dhcpcd_nodev %}
+
+# Disable device management to avoid "libudev: received NULL device" log spam
+nodev
+{% endif %}
 
 # Allow users of this group to interact with dhcpcd via the control socket.
 {% if dhcpcd_controlgroup is defined %}