fence_kdump_send fails to resolve hostname of destination cluster nodes listed in fence_kdump_nodes

Environment

• Red Hat Enterprise Linux 7
• Pacemaker cluster with fence_kdump resource

Issue

• When using fence_kdump to capture vmcore of cluster node before it gets fenced the fence_kdump fails when hostnames are used in fence_kdump_nodes in kdump congifuration file (/etc/kdump.conf). When IP addresses or FQDN are used instead hostnames then fence_kdump works as expected.

Resolution

• Update to kexec-tools-2.0.15-21.el7 or later. From the version and later the /etc/hosts and /etc/nsswitch are included in intiramfs in following cases:

  A. If fence_kdump_nodes is configured in kdump.conf the /etc/hosts and /etc/nsswitch are included into initramfs
  B. If fence_kdump_nodes is not configured in kdump.conf but fence_kdump stonith resource is configured in pacemaker /etc/hosts and /etc/nsswitch are included into initramfs

WORKAROUND for earlier releases:

• Include /etc/hosts and /etc/nsswitch.conf into initramfs generated by kdump by adding following parameter into /etc/kdump.conf:

  dracut_args --install "/etc/hosts" --install "/etc/nsswitch.conf"
  

  This will make hostnames and aliases listed in /etc/hosts resolvable from crashkernel.

Root Cause

• Initramfs by default doesn't contain files /etc/hosts and /etc/nsswitch.conf so nodename aliases listed in /etc/hosts are not resolvable from crashkernel by default. This results in fence_kdump failure in case IP addresses or FQDN via DNS are not listed in fence_kdump_nodes parameter.
• The bug was tracked on This content is not included.BZ#1543902.

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