hc_wrap

#!/bin/bash
# Usage:
# Replace the CRON shell with this script.
# In the crontab set to call this wrapper instead of "sh"
#    SHELL=.../log_wrap
# and tell us the previous shell cron used
#    OLD_SHELL = /bin/sh
#
# Then the cron record format changes to
# m h    dom mon dow    check name     command
# 23 *    *   *   *     "server online" df -h
# 64 21   *   *   *     "server backup" /root/backup --onedisk /


#### Logging
LOG_PATH=${HOME}/.healthchecks
LOG_FILE=wrap_cmd

if [[ ${HC_DEBUG} ]]; then
  mkdir -p ${LOG_PATH} > /dev/null
  rm ${LOG_PATH}/${LOG_FILE} > /dev/null
fi
log_cmd()
{
  if [[ ${HC_DEBUG} ]]; then
    echo "[${LOGNAME}][`date -Is`] - ${*}" >> ${LOG_PATH}/${LOG_FILE}
  fi
}

#### command split
hc_name=
hc_command=

split_name_command()
{
  local argv="$@"
  # Quotes surround name
  local pattern_1='^[ 	]*\"(.*)\" (.*)$'
  # One word name
  local pattern_2='^[ 	]*(\w+) (.*)$'
  
  if [[ $argv =~ ${pattern_1} ]]; then
    hc_name=${BASH_REMATCH[1]}
    hc_command="${BASH_REMATCH[2]}"
  elif [[ $argv =~ ${pattern_2} ]]; then
    hc_name=${BASH_REMATCH[1]}
    hc_command="${BASH_REMATCH[2]}"  
  fi
}

#### Settings
# settings will be read from:
# $HOME/.hc_wrap_config
# /etc/healthchecks_config (optional)
# crontab variables
config_file=${HOME}/.hc_wrap_config

# create a template config file if it does not yet exist
if [[ ! -r $config_file ]]; then
  cat << EOF > $config_file
# The API key for accessing the server 
#API_KEY=sUHYjHWeyJ8yRbbpvtbhw7cIDrVEfpQi

# The api URL for querying the server
#HC_API_URL=https://hc-ping.com/api/v1/checks

# e.g. https://hc-ping.com/b6f811ed-1718-4538-bd36-4f4b7376596a
#https://hc-ping.com/b6f811ed-1718-4538-bd36-4f4b7376596a = server online
#https://hc-ping.com/63219b04-4072-431a-a7c0-d5336d1a431b = server backup

EOF
fi

# called with config file name
parse_config()
{
  if [[ ! -r $1 ]]; then
    return
  fi
  
  local lhs rhs
  while IFS='= ' read -r lhs rhs
  do
    if [[ ! $lhs =~ ^\ *# && -n $lhs ]]; then
      rhs="${rhs%%\#*}"    # Del in line right comments
      rhs="${rhs%%*( )}"   # Del trailing spaces
      rhs="${rhs%\"*}"     # Del opening string quotes 
      rhs="${rhs#\"*}"     # Del closing string quotes 
      set_config $lhs "$rhs"
    fi
  done < $1
}

declare API_KEY HC_API_URL
declare -A ping_urls
set_config()
{
  log_cmd "config - $@"
  case $1 in
    API_KEY) API_KEY=$2 ;;
    HC_API_URL) HC_API_URL=$2 ;;
    *)
      ping_urls["$2"]="$1"
      ;;
  esac
}

#### Get ping url
hc_ping_url=
# called with task name
get_ping_url()
{
  hc_ping_url=${ping_urls["$1"]}
  if [[ -n $hc_ping_url ]]; then
    log_cmd "Found url: $hc_ping_url"
    return
  fi
  log_cmd "Create url for: $1"
  local response data
#  "api_key": "${API_KEY}", 

  read -r -d '' data << EOF
{ 
  "name": "${hc_name}", 
  "unique": ["name"], 
  "timeout": 86400,
  "channels": "*"
}
EOF
  log_cmd "$data"
  response=$( 
    curl ${HC_API_URL} \
      --header "X-Api-Key: ${API_KEY}" \
      --data "${data}"
  )
  local response_status=$?
  log_cmd "response - $response_status $response"
  if [[ $response_status -ne 0 ]]; then
    log_cmd "error connecting to server api"
    return
  fi

  # response comes back as a single line
  hc_ping_url=$(echo "${response}" | jq --raw-output '.ping_url' )
  log_cmd "hc_ping_url: $hc_ping_url"
  if [[ -n $hc_ping_url ]]; then
    echo "${hc_ping_url} = $1" >> $config_file
  fi
}

#### Poll server
poll_server()
{
  log_cmd "poll: $1"
  # server logs the first 10k
  echo "${2:0:10000}" |
  curl -fsS --retry 3 --request POST --data-binary @- $1 >/dev/null

  log_cmd "poll ret $?"
}

#### ########
if [[ ${HC_DEBUG} ]]; then
  env > ${LOG_PATH}/wrap_vars
fi
log_cmd "$@"
# get rid of the '-c'
shift
split_name_command "$1"

log_cmd "hc_name: $hc_name"
log_cmd "hc_command: $hc_command"

parse_config $config_file

if [[ ${HC_DEBUG} ]]; then
  declare -p API_KEY HC_API_URL ping_urls >> ${LOG_PATH}/${LOG_FILE}
fi

get_ping_url "$hc_name"

poll_server "${hc_ping_url}/start"
# make fd/5 an alias of stdout
exec 5>&1

hc_out=$( $OLD_SHELL -c "$hc_command" |& tee /dev/fd/5 | { head -n 10000; cat >/dev/null; }; exit ${PIPESTATUS[0]} )
hc_exit=$?

if [[ ${HC_DEBUG} ]]; then
  log_cmd "hc_exit: $hc_exit"
  log_cmd "hc_out-"
  echo "${hc_out}" >> ${LOG_PATH}/${LOG_FILE}
  log_cmd "hc_out-"
fi

fail_tag=
if [[ ${hc_exit} -ne 0 ]]; then
  fail_tag=/fail
fi
  
poll_server "${hc_ping_url}${fail_tag}" "${hc_out}"