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Bug 1809345: templates: add etc-networkmanager-dispatcher.d-90-long-hostname.yaml #1711

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Merged
openshift-merge-robot merged 1 commit into from
May 5, 2020
Merged

Bug 1809345: templates: add etc-networkmanager-dispatcher.d-90-long-hostname.yaml #1711

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40 changes: 40 additions & 0 deletions templates/common/_base/files/etc-networkmanager-dispatcher.d-90-long-hostname.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
filesystem: "root"
mode: 0755
path: "/etc/NetworkManager/dispatcher.d/90-long-hostname"
contents:
inline: |
#!/bin/bash
#
# On Google Compute Platform (GCP) the hostname may be too long (>63 chars).
# During firstboot the hostname is set in the initramfs before NetworkManager
# runs; on reboot affect nodes use 'localhost'. This hook is a simple work
# around: if the host name is longer than 63 characters, then the hostname
# is truncated at the _first_ dot.
#
# Additionally, this hook does not break DNS or cluster DNS resolution,
# since NetworkManager sets the appropriate /etc/resolv.conf settings.

IF=$1
STATUS=$2

log() { logger --tag "network-manager/$(basename $0)" "${@}"; }

# capture all eligible hostnames
if [[ ! "$(/bin/hostname)" =~ (localhost|localhost.local) ]]; then
log "hostname is already set"
exit 0
fi

if [[ ! "$STATUS" =~ (up|hostname|dhcp4-change|dhcp6-change) ]]; then
exit 0
fi

default_host="${DHCP4_HOST_NAME:-$DHCP6_HOST_NAME}"
# truncate the hostname to the first dot and than 64 characters.
host=$(echo ${default_host} | cut -f1 -d'.' | cut -c -63)
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@ashcrow ashcrow May 5, 2020

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$ echo "averylonghostnamewhichshouldprobablybelessbecausereallyitsprettycrazy.to.have.such.long.names" | cut -f1 -d'.' | cut -c -63
averylonghostnamewhichshouldprobablybelessbecausereallyitsprett
$ echo -n "averylonghostnamewhichshouldprobablybelessbecausereallyitsprettycrazy.to.have.such.long.names" | cut -f1 -d'.' | cut -c -63 | wc -c
64

Enforces 64 char limit. However, the next check on default host is >63. Should this check really be limiting to 63 instead?

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@ashcrow ashcrow May 5, 2020

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Other than this, LGTM!

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@darkmuggle darkmuggle May 5, 2020 •
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Ha! I did the same thing:

$ echo hi | cut -c -2 | wc -c
3

wc -c counts from 1

It warms my heart that we both thought of and ran the same test.

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@ashcrow ashcrow May 5, 2020

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Ahh 👍


if [ "${#default_host}" -gt 63 ]; then
log "discovered hostname is longer than than 63 characters"
log "truncating ${default_host} => ${host}"
/bin/hostnamectl --transient set-hostname "${host}"
fi