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check_elasticache.py
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check_elasticache.py
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#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2014 Carles Amigó <[email protected]>
#
# Distributed under terms of the MIT license.
"""
Nagios plugin for Amazon ElastiCache monitoring
Somehow inspired from the pmp-check-aws-rds.py script from the Percona
Monitoring Toolkit
"""
import boto.elasticache
import boto.ec2.cloudwatch
import argparse
import sys
import datetime
import json
def get_cluster_info(region, identifier=None):
"""Function for fetching ElastiCache details"""
elasticache = boto.elasticache.connect_to_region(region)
try:
if identifier:
info = elasticache.describe_cache_clusters(
identifier,
show_cache_node_info=True)[
'DescribeCacheClustersResponse'][
'DescribeCacheClustersResult'][
'CacheClusters'][0]
else:
info = [v['CacheClusterId']
for v in elasticache.describe_cache_clusters()[
'DescribeCacheClustersResponse'][
'DescribeCacheClustersResult'][
'CacheClusters']]
except boto.exception.BotoServerError:
info = None
return info
def get_cluster_stats(region, node, step, start_time, end_time, metric,
identifier):
"""Function for fetching ElastiCache statistics from CloudWatch"""
cw = boto.ec2.cloudwatch.connect_to_region(region)
result = cw.get_metric_statistics(step,
start_time,
end_time,
metric,
'AWS/ElastiCache',
'Average',
dimensions={
'CacheClusterId': [identifier],
'CacheNodeId': ['%04d' % node],
}
)
if result:
if len(result) > 1:
# Get the last point
result = sorted(result, key=lambda k: k['Timestamp'])
result.reverse()
result = float('%.2f' % result[0]['Average'])
return result
def main():
"""Main function"""
# Nagios status codes
OK = 0
WARNING = 1
CRITICAL = 2
UNKNOWN = 3
short_status = {OK: 'OK',
WARNING: 'WARN',
CRITICAL: 'CRIT',
UNKNOWN: 'UNK'}
# Cache instance classes as listed on
# http://aws.amazon.com/elasticache/pricing/
# For redis_maxmemory:
# http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/CacheParameterGroups.Redis.html # noqa
elasticache_classes = {
'cache.t2.micro': {
'memory': 0.555,
'redis_maxmemory': 581959680,
'vcpu': 1},
'cache.t2.small': {
'memory': 1.55,
'redis_maxmemory': 1665138688,
'vcpu': 1},
'cache.t2.medium': {
'memory': 3.22,
'redis_maxmemory': 3461349376,
'vcpu': 2},
'cache.m3.medium': {
'memory': 2.78,
'redis_maxmemory': 2988441600,
'vcpu': 1},
'cache.m3.large': {
'memory': 6.05,
'redis_maxmemory': 6501171200,
'vcpu': 2},
'cache.m3.xlarge': {
'memory': 13.3,
'redis_maxmemory': 14260633600,
'vcpu': 4},
'cache.m3.2xlarge': {
'memory': 27.9,
'redis_maxmemory': 29989273600,
'vcpu': 8},
'cache.r3.large': {
'memory': 13.5,
'redis_maxmemory': 14470348800,
'vcpu': 2},
'cache.r3.xlarge': {
'memory': 28.4,
'redis_maxmemory': 30513561600,
'vcpu': 4},
'cache.r3.2xlarge': {
'memory': 58.2,
'redis_maxmemory': 62495129600,
'vcpu': 8},
'cache.r3.4xlarge': {
'memory': 118,
'redis_maxmemory': 126458265600,
'vcpu': 16},
'cache.r3.8xlarge': {
'memory': 237,
'redis_maxmemory': 254384537600,
'vcpu': 32},
'cache.m1.small': {
'memory': 1.3,
'redis_maxmemory': 943718400,
'vcpu': 1},
'cache.m1.medium': {
'memory': 3.35,
'redis_maxmemory': 3093299200,
'vcpu': 1},
'cache.m1.large': {
'memory': 7.1,
'redis_maxmemory': 7025459200,
'vcpu': 2},
'cache.m1.xlarge': {
'memory': 14.6,
'redis_maxmemory': 14889779200,
'vcpu': 4},
'cache.m2.xlarge': {
'memory': 16.7,
'redis_maxmemory': 17091788800,
'vcpu': 2},
'cache.m2.2xlarge': {
'memory': 33.8,
'redis_maxmemory': 35022438400,
'vcpu': 4},
'cache.m2.4xlarge': {
'memory': 68,
'redis_maxmemory': 70883737600,
'vcpu': 8},
'cache.c1.xlarge': {
'memory': 6.6,
'redis_maxmemory': 6501171200,
'vcpu': 8},
'cache.t1.micro': {
'memory': 0.213,
'redis_maxmemory': 142606336,
'vcpu': 1}}
# ElastiCache metrics as listed on
# http://docs.aws.amazon.com/AmazonCloudWatch/latest/DeveloperGuide/elasticache-metricscollected.html # noqa
metrics = {'status': 'ElastiCache availability',
'cpu': 'CPUUtilization',
'memory': 'BytesUsedForCache',
'swap': 'SwapUsage'}
units = ('percent', 'GB')
# Parse options
parser = argparse.ArgumentParser()
parser.add_argument('-r', '--region', help='AWS region', required=True)
parser.add_argument('-l', '--list',
help='list of all ElastiCache clusters',
action='store_true', default=False,
dest='cluster_list')
parser.add_argument('-i', '--ident', help='ElastiCache cluster identifier')
parser.add_argument('-p', '--print', help='print status and other ' +
'details for a given ElastiCache cluster',
action='store_true', default=False, dest='info')
parser.add_argument('-m', '--metric', help='metric to check: [%s]' %
', '.join(metrics.keys()))
parser.add_argument('-n', '--node',
help='check only specified node number',
type=int, default=1)
parser.add_argument('-w', '--warn', help='warning threshold')
parser.add_argument('-c', '--crit', help='critical threshold')
parser.add_argument('-u', '--unit', help='unit of thresholds for "memory" '
'metrics: [%s]. Default: percent' % ', '.join(units),
default='percent')
parser.add_argument('--no-threshold-calc', help='in redis do not ' +
'calculate the correct threshold acording the number' +
' of cpus', action='store_true', default=False,
dest='no_threshold_calc')
options = parser.parse_args()
# Check args
if len(sys.argv) == 1:
parser.print_help()
sys.exit()
elif not options.region:
parser.print_help()
parser.error('AWS region is not set.')
elif options.cluster_list:
info = get_cluster_info(options.region)
print(json.dumps(info, indent=2))
sys.exit()
elif not options.ident:
parser.print_help()
parser.error('ElastiCache identifier is not set.')
elif options.info:
info = get_cluster_info(options.region, options.ident)
if info:
print(json.dumps(info, indent=2))
else:
print 'No ElastiCache cluster "%s" found on your AWS account.' % \
options.ident
sys.exit()
elif not options.metric or options.metric not in metrics.keys():
parser.print_help()
parser.error('Metric is not set or not valid.')
elif not options.warn and options.metric != 'status':
parser.print_help()
parser.error('Warning threshold is not set.')
elif not options.crit and options.metric != 'status':
parser.print_help()
parser.error('Critical threshold is not set.')
tm = datetime.datetime.utcnow()
status = None
note = ''
perf_data = None
# ElastiCache Status
if options.metric == 'status':
info = get_cluster_info(options.region, options.ident)
if not info:
status = CRITICAL
note = 'Unable to get ElastiCache cluster'
else:
status = OK
note = '%s %s. Status: %s' % (info['Engine'],
info['EngineVersion'],
info['CacheClusterStatus'])
# ElastiCache Load Average
elif options.metric == 'cpu':
info = get_cluster_info(options.region, options.ident)
if not info:
status = UNKNOWN
note = 'Unable to get ElastiCache details and statistics'
else:
# Check thresholds
try:
warns = [float(x) for x in options.warn.split(',')]
crits = [float(x) for x in options.crit.split(',')]
fail = len(warns) + len(crits)
except:
fail = 0
if fail != 6:
parser.error('Warning and critical thresholds should be 3 ' +
'comma separated numbers, e.g. 20,15,10')
# Because redis only uses 1 cpu, we need to calculate the new
# thresholds as explained in
# http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/CacheMetrics.WhichShouldIMonitor.html # noqa
if not options.no_threshold_calc and info['Engine'] == 'redis':
warns = [x / elasticache_classes[info['CacheNodeType']]['vcpu']
for x in warns]
crits = [x / elasticache_classes[info['CacheNodeType']]['vcpu']
for x in crits]
cpus = []
fail = False
j = 0
perf_data = []
for i in [1, 5, 15]:
if i == 1:
# Some stats are delaying to update on CloudWatch.
# Let's pick a few points for 1-min cpu avg and get the
# last point.
n = 5
else:
n = i
cpu = get_cluster_stats(options.region, options.node, i * 60,
tm - datetime.timedelta(
seconds=n * 60),
tm, metrics[options.metric],
options.ident)
if not cpu:
status = UNKNOWN
note = 'Unable to get ElastiCache statistics'
perf_data = None
break
cpus.append(str(cpu))
perf_data.append('cpu%s=%s;%s;%s;0;100' % (i, cpu, warns[j],
crits[j]))
# Compare thresholds
if not fail:
if warns[j] > crits[j]:
parser.error('Parameter inconsistency: warning ' +
' threshold is greater than critical.')
elif cpu >= crits[j]:
status = CRITICAL
fail = True
elif cpu >= warns[j]:
status = WARNING
j = j + 1
if status != UNKNOWN:
if status is None:
status = OK
note = 'Load average: %s%%' % '%, '.join(cpus)
perf_data = ' '.join(perf_data)
# ElastiCache Free Memory
elif options.metric in ['memory']:
# Check thresholds
try:
warn = float(options.warn)
crit = float(options.crit)
except:
parser.error('Warning and critical thresholds should be integers.')
if crit < warn:
parser.error('Parameter inconsistency: critical threshold is ' +
'lower than warning.')
if options.unit not in units:
parser.print_help()
parser.error('Unit is not valid.')
info = get_cluster_info(options.region, options.ident)
used_memory = get_cluster_stats(options.region, options.node, 60, tm -
datetime.timedelta(seconds=60), tm,
metrics[options.metric], options.ident)
if not info or not used_memory:
status = UNKNOWN
note = 'Unable to get ElastiCache details and statistics'
else:
try:
max_memory = float(elasticache_classes[
info['CacheNodeType']]['redis_maxmemory'])
except:
print 'Unknown ElastiCache instance class "%s"' % \
info.instance_class
sys.exit(UNKNOWN)
# free = '%.2f' % (free / 1024 ** 3)
# free_pct = '%.2f' % (float(free) / storage * 100)
used_percent = used_memory / max_memory * 100
if options.unit == 'percent':
val = used_percent
val_max = 100
elif options.unit == 'GB':
val = used_memory
val_max = max_memory
# Compare thresholds
if val >= crit:
status = CRITICAL
elif val >= warn:
status = WARNING
if status is None:
status = OK
note = 'Used %s: %.2f GB (%.0f%%) of %.2f GB' % \
(options.metric, used_memory/1024/1024/1024,
float(used_percent),
max_memory/1024/1024/1024)
perf_data = 'used_%s=%s;%s;%s;0;%s' % (options.metric,
val,
warn,
crit,
val_max)
# ElastiCache swap
elif options.metric in ['swap']:
# Check thresholds
try:
warn = float(options.warn)
crit = float(options.crit)
except:
parser.error('Warning and critical thresholds should be integers.')
if crit < warn:
parser.error('Parameter inconsistency: critical threshold is ' +
'greater than warning.')
info = get_cluster_info(options.region, options.ident)
swap = get_cluster_stats(options.region, options.node, 60, tm -
datetime.timedelta(seconds=60), tm,
metrics[options.metric], options.ident)
if not info or not isinstance(swap, float):
status = UNKNOWN
note = 'Unable to get ElastiCache details and statistics'
else:
# Convert Bytes to MB
swap = swap / 1000000
# Compare thresholds
if swap >= crit:
status = CRITICAL
elif swap >= warn:
status = WARNING
if status is None:
status = OK
note = 'Used swap %s MB' % swap
perf_data = 'swap=%sMB;%s;%s;0;' % (swap,
warn,
crit)
# Final output
if status != UNKNOWN and perf_data:
print '%s %s | %s' % (short_status[status], note, perf_data)
else:
print '%s %s' % (short_status[status], note)
sys.exit(status)
if __name__ == '__main__':
main()