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#!/usr/bin/env bash
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# vim:ts=4:sts=4:sw=4:et
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#
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# Author: Hari Sekhon
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# Date: 2020-01-16 12:22:40 +0000 (Thu, 16 Jan 2020)
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#
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# https://github.com/HariSekhon/DevOps-Bash-tools
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#
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# License: see accompanying Hari Sekhon LICENSE file
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#
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# If you're using my code you're welcome to connect with me on LinkedIn and optionally send me feedback to help steer this or other code I publish
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#
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# https://www.linkedin.com/in/HariSekhon
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#
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# Script to print a random Hadoop node by parsing the Hadoop topology map from /etc
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#
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# Tested on CDH 5.10
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#
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# See also:
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#
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# find_active_*.py - https://github.com/HariSekhon/DevOps-Python-tools
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#
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# HAProxy Configs for many Hadoop and other technologies - https://github.com/HariSekhon/HAProxy-configs
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#
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set -euo pipefail
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[ -n "${DEBUG:-}" ] && set -x
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topology_map="${HADOOP_TOPOLOGY_MAP:-/etc/hadoop/conf/topology.map}"
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if ! [ -f "$topology_map" ]; then
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echo "File not found: $topology_map. Did you run this on a Hadoop node?" >&2
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exit 1
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fi
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# returns datanodes in the topology map by omitting nodes with that are masters / namenodes / control nodes
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awk -F'"' '/<node name="[A-Za-z]/{print $2}' "$topology_map" |
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grep -Ev '^[^.]*(name|master|control)' |
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shuf -n 1
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