#!/usr/bin/env python3
#
# HBase Prometheus Exporter
#
# Björn Busse <bj.rn@baerlin.eu>
#
#
# TODO:
#
#  * Remove timestamp from log msg or make them optional,
#    we already have it in the journal -
#    at least when not running in a container
#
#  * Ask ZooKeeper directly for active namenode/hbase master
#
#  * Add an option to relay all metrics
#
#  * Add hdfs/hbase binaries to container
#
#  * Fix command line argument handling
#
#  * Add loglevel and other missing args

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

import argparse
from bs4 import BeautifulSoup
from flatten_json import flatten
import io
import json
from kazoo import client as kz_client
import logging
import os
from prometheus_client import start_http_server, Summary
from prometheus_client.core import GaugeMetricFamily, REGISTRY
from prometheus_client import Gauge
import random
import re
import requests
import subprocess
from subprocess import Popen,PIPE
import sys
import time
import traceback
import xml.etree.ElementTree as et

tmp_path = '/tmp/'
logpath = tmp_path

# ZooKeeper
zk_reconnect_interval_s = 30

prom_scrape_interval_s = 10

# Prom vars
REQUEST_TIME = Summary('request_processing_seconds', 'Time spent processing request')
prom_hbase_num_regions_in_transition_stale = Gauge('number_of_regions_in_transition_stale', 'Number of stale regions in transition')
prom_hbase_num_inconsistencies = Gauge('number_of_inconsistencies', 'Number of inconsistencies in HBase')
prom_hdfs_total = Gauge('hdfs_bytes_total', 'HDFS total bytes')
prom_hdfs_used = Gauge('hdfs_bytes_used', 'HDFS used bytes')
prom_hdfs_remaining = Gauge('hdfs_bytes_remaining', 'HDFS remaining bytes')
prom_hdfs_num_datanodes_live = Gauge('hdfs_datanodes_live', 'HDFS Live DataNodes')
prom_hdfs_num_datanodes_dead = Gauge('hdfs_datanodes_dead', 'HDFS Dead DataNodes')
prom_hbase_up = Gauge('hbase_up', 'HBase is up and running, a master is elected')
prom_hbase_healthy = Gauge('hbase_healthy', 'HBase is up and running, a master is elected, no inconsistencies are detected, hbase is queryable')
prom_hbase_num_regionservers_live = Gauge('hbase_regionservers_live', 'HBase Live Regionservers')
prom_hbase_num_regionservers_dead = Gauge('hbase_regionservers_dead', 'HBase Dead Regionservers')
prom_hbase_num_clusterrequests = Gauge('hbase_clusterrequests', 'HBase Clusterrequests')

# HDFS/HBase
hdfs_config_file = "/etc/hadoop/conf/hdfs-site.xml"
cmd_hbase_active_master = ['/usr/hdp/current/hbase-client/bin/hbase-jruby', '/usr/hdp/current/hbase-client/bin/get-active-master.rb']
cmd_hbase_hbck = ['hbase', 'hbck']
cmd_hdfs_namenodes = ['hdfs', 'getconf', '-namenodes']

# Use command line arguments to set the following vars
# Do not change them here (See TODO)
namenodes = ""
namenode_use_tls = False
hbase_master_ui_default_port = 16010
hdfs_namenode_default_port = 50070
cluster_is_kerberized = False


class zk():
    zk_client = ""

    @classmethod
    def main(self, address, timeout=5):

        zk_client = kz_client.KazooClient(address)

        try:
            zk_client.start(timeout)
        except Exception as e:
            logging.debug("ZooKeeper Error: " + str(e))
            return False

        self.zk_client = zk_client
        self.zk_client.add_listener(self.listener)

        return True

    def listener(state):
        if state == kz_client.KazooState.CONNECTED:
            logging.info("ZooKeeper: Client connected")
        else:
            logging.info("ZooKeeper: Failed to connect to ZooKeeper")

    @classmethod
    def get_znode_data(self, znode):
        data = ""

        try:
            self.zk_client.exists(znode)
        except Exception as e:
            logging.info("ZooKeeper: znode does not exist: " + znode)
            return False

        try:
            data = self.zk_client.get(znode)
        except:
            logging.info("ZooKeeper: Could not get znode data from " + znode)
            return False

        return data

    def listener(state):
        if state == KazooState.LOST:
            logging.debug("ZooKeeper: Connection lost")
            # Register somewhere that the session was lost
        elif state == KazooState.SUSPENDED:
            logging.debug("ZooKeeper: Connection suspended")
            # Handle being disconnected from Zookeeper
        else:
            logging.debug("ZooKeeper: Connection re-established")
            # Handle being connected/reconnected to Zookeeper


class jmx_query():

    def main(self, hdfs_namenode_hosts):

        hdfs_active_namenode = self.get_active_namenode()
        hbase_active_master = hbase_exporter.get_active_master()

        if not hdfs_active_namenode:
            logging.info("Failed to determine active HDFS namenode")
            return False

        if not hbase_active_master:
            logging.info("Failed to determine active HBase master")
            return False

        url = self.get_url('hdfs', hdfs_active_namenode)
        self.get_jmx_data(url)
        url = self.get_url('hbase', hbase_active_master)
        self.get_jmx_data(url)


    def get_url(self, service, hostname):

        if (namenode_use_tls):
            url_scheme = "https://"
        else:
            url_scheme = "http://"

        if service == 'hdfs':
            url = url_scheme + hostname + ":" + str(hdfs_namenode_default_port) + "/jmx"
        elif service == 'hbase':
            url = url_scheme + hostname + ":" + str(hbase_master_ui_default_port) + "/jmx"
        return url


    def get_jmx_data(self, url):
        jmx = self.query(url)

        if (jmx == False):
            logging.info("Could not read jmx data from: " + url)
            return False

        for k, v in jmx.items():
            if not v is None:
                self.lookup_keys(k, v)

        return True


    def get_active_namenode(hdfs_namenode_hosts):

        if not which(cmd_hdfs_namenodes[0]):
            logging.info("Could not find hdfs executable in PATH")
            return False

        try:
            r = subprocess.run(cmd_hdfs_namenodes, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        except Exception as e:
            logging.debug("Type error: " + str(e))
            logging.info("Failed to determine active master")
            return False

        hosts = r.stdout.decode('utf-8').split(" ")

        tree = et.parse(hdfs_config_file)
        root = tree.getroot()
        has_ha_element = False
        active_namenode = None

        if has_ha_element:
            logging.info("Hadoop High-Availability: True")
        else:
            logging.info("Hadoop High-Availability: False")

        for property in root:
            if "dfs.ha.namenodes" in property.find("name").text:
                has_ha_element = True
                nameservice_id = property.find("name").text[len("dfs.ha.namenodes")+1:]
                namenodes = property.find("value").text.split(",")

        for node in namenodes:
            # Get namenode address and check if it is the active node
            for n in root:
                prefix = "dfs.namenode.rpc-address." + nameservice_id + "."
                element_text = n.find("name").text

                if prefix in element_text:
                    node_address = n.find("value").text.split(":")[0]

            cmd = ['hdfs haadmin -getServiceState ' + node]
            r = subprocess.run(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

            if len(r.stderr.decode("utf-8")) > 0:
                logging.debug(r.stderr.decode("utf-8"))

            if "active" in r.stdout.decode("utf-8").lower():
                logging.info("Active namenode: " + node_address + " (" + node + ")")
                return node_address

        return False


    def query(self, url):

        try:
            r = requests.get(url)
        except Exception as e:
            logging.info("Could not connect to: " + url)
            return False

        jmx = json.loads(r.text)
        jmx = flatten(jmx)
        return(jmx)


    def lookup_keys(self, key, value):
        if   key.endswith("capacityUsed"):
            prom_hdfs_used.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("capacityTotal"):
            prom_hdfs_total.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("capacityRemaining"):
            prom_hdfs_remaining.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("NumLiveDataNodes"):
            prom_hdfs_num_datanodes_live.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("NumDeadDataNodes"):
            prom_hdfs_num_datanodes_dead.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("numRegionServers"):
            prom_hbase_num_regionservers_live.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("numDeadRegionServers"):
            prom_hbase_num_regionservers_dead.set(value)
            logging.debug("Found jmx key: " + key)
        elif key.endswith("clusterRequests"):
            prom_hbase_num_clusterrequests.set(value)
            logging.debug("Found jmx key: " + key)


class hbase_exporter():

    def main(self, hbase_master_hosts):
        hbase_active_master = self.get_active_master()

        if not hbase_active_master:
            logging.info("Failed to determine active HBase master")
            prom_hbase_up.set(0)
            prom_hbase_healthy.set(0)
            return False

        self.get_stale_regions_in_transition(hbase_active_master)
        self.hbck_get_inconsistencies()
        self.check_health()


    def check_health():
        if self.num_inconsistencies > 0:
            prom_hbase_healthy.set(0)
            return False

        if prom_ihbase_regions_in_transition_stale > 0:
            prom_hbase_healthy.set(0)
            return False

        prom_hbase_up.set(1)
        prom_hbase_healthy.set(1)

        return True


    @staticmethod
    def get_active_master():

        if not which(cmd_hbase_active_master[0]):
            logging.info("Could not find hdfs executable in PATH")
            return False

        try:
            r = subprocess.run(cmd_hbase_active_master, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        except:
            return False

        if 'Master not running' in r.stdout.decode('utf-8'):
            return False

        prom_hbase_up.set(1)
        active_master = r.stdout.decode('utf-8').rstrip()
        logging.info("Active master: " + active_master)

        return active_master


    def get_stale_regions_in_transition(self, hbase_master):
        host = hbase_master.rstrip("\n\r")
        port = hbase_master_ui_default_port
        url = 'http://%(host)s:%(port)s/master-status' % locals()

        logging.debug('GET %s', url)

        try:
            req = requests.get(url)
        except requests.exceptions.RequestException as e:
            logging.debug(e)
            logging.debug('Failed to request ' + url)
            return False

        logging.debug("Response: %s %s", req.status_code, req.reason)

        if req.status_code != 200:
            logging.debug('Got a http return code != 200')

        num_regions_in_transition_stale = self.hbaseui_parse_output(req.content)

        if num_regions_in_transition_stale is None:
            logging.debug('Parse error - failed to find number of stale regions in transition')

        if not isinstance(num_regions_in_transition_stale, int):
            logging.debug('Parse error - got non-integer for stale regions in transition')

        msg = '{0} stale regions in transition '\
                   .format(num_regions_in_transition_stale)

        prom_hbase_num_regions_in_transition_stale.set(num_regions_in_transition_stale)
        logging.info(msg)

        return num_regions_in_transition_stale


    def hbaseui_parse_output(self, content):
        soup = BeautifulSoup(content, 'html.parser')
        num_regions_in_transition_stale = 0
        try:
            headings = soup.findAll('h2')
            for heading in headings:
                if heading.get_text() == "Regions in Transition":
                    logging.debug('Found Regions in Transition section header')
                    logging.debug('Looking for table')
                    table = heading.find_next('table')
                    num_regions_in_transition_stale = self.hbaseui_parse_table(table)
                    if not isinstance(num_regions_in_transition_stale, int):
                        logging.debug('Got non-integer \'{0}\' for stale regions in transition when parsing HBase Master UI'\
                              .format(num_regions_in_transition_stale))

            return num_regions_in_transition_stale

        except (AttributeError, TypeError):
            logging.info('Failed to parse HBase Master UI status page')


    def hbck_get_inconsistencies(self):

        re_status = re.compile(r'^Status:\s*(.+?)\s*$')
        re_inconsistencies = re.compile(r'^\s*(\d+)\s+inconsistencies\s+detected\.?\s*$')
        num_inconsistencies = None
        hbck_status = None

        logging.info("HBase: Running hbck consistency check")
        p = Popen(['hbase', 'hbck'], stdout=PIPE, stderr=PIPE, close_fds=False)
        output, error = p.communicate()
        output = output.splitlines()

        if p.returncode != 0:
            logging.info("Failed to run hbck (%d)" % (p.returncode))
            return False

        for line in output:
            match = re_inconsistencies.match(line)

            if match:
                num_inconsistencies = match.group(1)
                logging.info('Number of inconsistencies:  %s', hbck_status)
                continue

                match = re_status.match(line)

            if match:
                hbck_status = match.group(1)
                logging.info('hbck status = %s', hbck_status)
                break

        if hbck_status is None:
            logging.info('Failed to find hbck status result')
        if num_inconsistencies is None:
            logging.info('Failed to find number of inconsistencies')

        if num_inconsistencies != None:
            num_inconsistencies = int(num_inconsistencies)

        if not isinstance(num_inconsistencies, int):
            logging.info('Error: Non-integer detected for the number of inconsistencies')
            return False

        self.num_inconsistencies = num_inconsistencies


    @staticmethod
    def hbaseui_parse_table(table):
        for row in table.findChildren('tr'):
            for col in row.findChildren('td'):
                if 'Regions in Transition for more than ' in col.get_text():
                    next_sibling = col.findNext('td')
                    num_regions_in_transition_stale = next_sibling.get_text().strip()
                    return num_regions_in_transition_stale
        return None


def which(program):

    def is_executable(fn):
        return os.path.isfile(fn) and os.access(fn, os.X_OK)

    filepath, fname = os.path.split(program)

    if filepath:
        if is_executable(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            exec_file = os.path.join(path, program)
            if is_executable(exec_file):
                return exec_file

    return None


if __name__ == '__main__':

    hbase_master_default_address = 'localhost:' + str(hbase_master_ui_default_port)
    hdfs_namenode_default_address = 'localhost:' + str(hdfs_namenode_default_port)

    parser = argparse.ArgumentParser( description="")
    parser.add_argument('--hbase-master', dest='hbase_master', action='append', help="HBase master address, can be specified multiple times", type=str, default=hbase_master_default_address)
    parser.add_argument('--hdfs-namenodes', dest='hdfs_namenode', action='append', help="HDFS namenode address, can be specified multiple times", type=str, default=hdfs_namenode_default_address)
    parser.add_argument('--zookeeper-server-address', dest='zookeeper_server', action='append', help="ZooKeeper server address, can be specified multiple times", type=str)
    parser.add_argument('--prometheus-exporter-port', dest='prom_http_port', help="Listen port for Prometheus export", type=int, default=9010)
    parser.add_argument('--logfile', dest='logfile', help="Path to optional logfile", type=str)
    parser.add_argument('--loglevel', dest='loglevel', help="Loglevel, default: INFO", type=str, default='INFO')

    args = parser.parse_args()
    prom_http_port = args.prom_http_port
    logfile = args.logfile
    loglevel = args.loglevel
    zookeeper_server = args.zookeeper_server
    hbase_master = args.hbase_master
    hdfs_namenodes = args.hdfs_namenode
    del locals()['args']

    # Optional File Logging
    if 'logfile' is not None:
        tlog = logfile.rsplit('/', 1)
        logpath = tlog[0]
        logfile = tlog[1]
        if not os.access(logpath, os.W_OK):
            # Our logger is not set up yet, so we use print here
            print("Logging: Can not write to directory. Skippking filelogging handler")
        else:
            fn = logpath + '/' + logfile
            file_handler = logging.FileHandler(filename=fn)
            # Our logger is not set up yet, so we use print here
            print("Logging: Logging to " + fn)

    stdout_handler = logging.StreamHandler(sys.stdout)

    if 'file_handler' in locals():
        handlers = [file_handler, stdout_handler]
    else:
        handlers = [stdout_handler]

    logging.basicConfig(
        level=logging.INFO,
        format='[%(asctime)s] {%(filename)s:%(lineno)d} %(levelname)s - %(message)s',
        handlers=handlers
    )

    logger = logging.getLogger(__name__)
    level = logging.getLevelName(loglevel)
    logger.setLevel(level)

    # Start the Prometheus server
    try:
        start_http_server(prom_http_port)
    except Exception as e:
        logging.debug("Failed to start Prometheus webserver: " + str(e))
        logging.info("There might be another instance of " + sys.argv[0] + \
                     " already running, can not bind to " + str(prom_http_port) + ", exiting..")
        sys.exit()

    nruns = 0

    # Start a ZooKeeper client
    r = False
    nzk = 0

    while not r:
        for zk_address in zookeeper_server:
            nzk += 1
            logging.info("ZooKeeper: Trying to connect to "
                          + zk_address
                          + ' (' + str(nzk) + '/' + str(len(zookeeper_server)) + ')')

            r = zk.main(zk_address)
            time.sleep(zk_reconnect_interval_s)

    if cluster_is_kerberized:
        znode_hbase = "/hbase"
    else:
        znode_hbase = "/hbase-unsecure"

    clusterid = zk.get_znode_data(znode_hbase + "/hbaseid")

    if not clusterid:
        logging.info("ZooKeeper: Could not read clusterid")
    else:
        logging.info("ZooKeeper: Clusterid: " + str(clusterid[0]))

    while True:
        m = zk.get_znode_data(znode_hbase + "/master")

        if not m:
            logging.info("ZooKeeper: Failed to get HBase master")
        else:
            logging.info("ZooKeeper: " + str(m[0]))

        jmx_query().main(hdfs_namenodes)
        hbase_exporter().main(hbase_master)

        nruns += 1

        if nruns == 1:
            logging.info("Started HBase exporter")

        time.sleep(prom_scrape_interval_s)