Creates cloudwatch log filter, metric and alarm

setup-cloudwatch.sh

#!/usr/bin/env bash
#title          : setup-cloudwatch.sh
#description    : Creates cloudwatch log filter, metric and alarm
#author         : Christian-André Giehl <christian@emailbrief.de>
#date           : 20190718
#version        : 1.1
#usage          : sh setup-cloudwatch.sh <keyword-list> <lambda-function-name>
#==============================================================================

# Exits in case the supplied state is != 0. State is typically supplied via $?
exitOnError() {
	state=$1
	msg=$2
	if [ $state -ne 0 ]; then
		echo "!!! ${msg}"
		echo "### Exiting."
		exit $state
	fi
}

confirmPrompt() {
    if [ ! -z "${HEADLESS}" ]; then
        echo "Headless! Auto-confirmed!"
        return 0
    fi
    read -p "-----> DO YOU WANT TO ${1}? [Yy]es " -n 1 -r </dev/tty
    if [[ $REPLY =~ ^[Yy]$ ]]
    then
        return 0
    fi
    return 1
}

escapePattern() {
    echo ${1}|sed 's/[^a-zA-Z0-9]/_/g'|cut -c1-20
}

printUsage() {
    echo "!!! Please specify exactly 2 args! !!!"
    echo "  Usage: sh setup-cloudwatch.sh <keyword-list> <lambda-function-name>"
    echo "  with:"
    echo "    <keyword-list>          a text-only file with one search string per line (don't forget the newline at EOF!)"
    echo "    <lambda-function-name>  name of your lambda function to be used as metric/filter naming"
}

if [ $# -ne 2 ]; then
    printUsage
    exit 1
fi

#
# 0. Input vars
#
command -v aws
exitOnError $? "AWS CLI not found or not accessible!"

INPUT_FILE=$1
LAMBDA_NAME=$2

LOG_GROUP_NAME=/aws/lambda/${LAMBDA_NAME}
METRIC_NAMESPACE=EbMetrics

while read p; do
    # Skip empty lines
    if [ -z "${p}" ]; then
        echo "Skipping '${p}' because it is empty!"
        continue
    fi

    # Skip commented lines
    if [[ "${p}" == \#* ]]; then
        echo "Skipping '${p}' because it is commented out!"
        continue
    fi

    FILTER_PATTERN=${p}
    FILTER_PATTERN_ESCAPED=$(escapePattern "${FILTER_PATTERN}")

    METRIC_NAME=${LAMBDA_NAME}-${FILTER_PATTERN_ESCAPED}-metric
    FILTER_NAME=${LAMBDA_NAME}-${FILTER_PATTERN_ESCAPED}-filter
    ALARM_NAME=${LAMBDA_NAME}-${FILTER_PATTERN_ESCAPED}-alarm

    #
    # 1. Log current situation
    #
    cmd="aws logs describe-metric-filters \
      --log-group-name ${LOG_GROUP_NAME}"

    # Storing the cmd and using eval here may look complicated but it simplifies calling the cmd more than once
    eval "${cmd}"
    TRY_FILTER=$(eval "${cmd}"|grep -c "\"filterName\": \"${FILTER_NAME}\"")
    if [ ${TRY_FILTER} -eq 1 ]; then
        echo "Filter '${FILTER_NAME}' already exists! Skipping..."
        continue
    fi

    aws cloudwatch describe-alarms-for-metric \
        --metric-name ${METRIC_NAME} \
        --namespace ${METRIC_NAMESPACE}

    #
    # 2. Create metric filter
    #
    confirmPrompt "create metric filter '${FILTER_NAME}'"
    exitOnError $? "!!! ABORTED !!!"
    aws logs put-metric-filter \
      --log-group-name ${LOG_GROUP_NAME} \
      --filter-name ${FILTER_NAME} \
      --filter-pattern "${FILTER_PATTERN}" \
      --metric-transformations \
      metricName=${METRIC_NAME},metricNamespace=${METRIC_NAMESPACE},metricValue=1,defaultValue=0

    #
    # 3. Create alarm
    #
    confirmPrompt "create alarm '${ALARM_NAME}'"
    exitOnError $? "!!! ABORTED !!!"
    aws cloudwatch put-metric-alarm \
        --alarm-name ${ALARM_NAME} \
        --metric-name ${METRIC_NAME} \
        --namespace ${METRIC_NAMESPACE} \
        --alarm-description "TODO" \
        --actions-enabled \
        --alarm-actions "arn:aws:sns:eu-central-1:216518302536:cwAlarmList" \
        --statistic "Sum" \
        --period 900 \
        --evaluation-periods 1 \
        --threshold 0 \
        --comparison-operator "GreaterThanThreshold" \
        --treat-missing-data "notBreaching"
        # --generate-cli-skeleton
done < ${INPUT_FILE}