GaryRogers

ElasticSearch Tuning in Anger

So. I ran into a great deal of stress around ElasticSearch/Logstash performance lately. These are just a few lessons learned, documented so I have a chance of finding them again.

Logs

Both ElasticSearch and Logstash produce logs. On my RHEL install they're located in /var/log/elasticsearch and /var/log/logstash. These will give you some idea of problems then things go really wrong. For example, in my case, ElasticSearch got so slow that Logstash would time out sending it logs. These issues show up in the logs. Also, Elasticsearch would start logging problems when JVM Garbage collection took longer than 30 seconds, which is a good indicator of memory pressure on ElasticSearch.

Pending Tasks

ElasticSearch (and Logstash when it's joined to an ES Cluster) processes tasks in a queue, that you can peek into. Before realizing this I didn't have any way to understand what was happening in ElasticSearch besides the logs. You can look at the pending tasks queue with this command

GaryRogers

NodeJS File parsing

Here's a skelleton for ripping files apart in NodeJS and processing each line.

var fs = require('fs');
var zlib = require('zlib');
var stream = require('stream');
var es = require('event-stream');

GaryRogers

Log Filtering

This is a filter/rating class to look at log objects and decide if they're interesting (worthy of review). Error messages are rated higher, as are logs from production hosts.

'use strict'

module.exports = function(options) {
  var my = {};

GaryRogers

Setting up InfluxDB on CentOS/RHEL

The InfluxDB Docs give you a very brief overview of installing InfluxDB on a host. It boils down to 'here's the RPM, install it.' That's fine for looking at the software, but you'll probably want to adjust the configuration a bit for a production environment.

Basic Install

https://influxdb.com/docs/v0.9/introduction/installation.html

Config changes

Modify /etc/opt/influxdb/influxdb.conf

GaryRogers

Using forms with Bootstrap-Dialog

var alertMessage = "";
var formTemplate = Backbone.Marionette.TemplateCache.get('#myTemplate');
var formString = formTemplate({ defaultDate: moment().add(90, 'days').format('YYYYMMDD') });

// remove the newlines. Bootstrap-Dialog doesn't like them (turns them into <br>'s)
formString = formString.replace(/[\n]/g, '');

GaryRogers

# Redis Debug Config to match on normal and warning Redis log lines.
input {
  stdin { codec => "plain" }
}

filter {
  grok {
    # Extends the normal redis pattern to account for warnings as well.
    match => [ "message", "\[%{POSINT:pid}\] %{REDISTIMESTAMP:timestamp} # %{LOGLEVEL:level} %{GREEDYDATA:mymessage}"]
    match => [ "message", "\[%{POSINT:pid}\] %{REDISTIMESTAMP:timestamp} \* %{GREEDYDATA:mymessage}"]

GaryRogers

# Docker file to create a CentOS Elasticsearch host.
FROM centos:centos6
MAINTAINER Gary Rogers <gary-rogers@uiowa.edu>

# Install things as roo
USER root

RUN \
  yum update -y --quiet && \
  yum install -y --quiet wget && \

GaryRogers

TestComplete Jenkins Integration Notes

Agent Node Setup

• Triple check your GPOs.
• Run Resultant Set of GPOs to make sure some up-stream GPO isn't doing something you don't expect.
• Shadow the RDP session to see what TestExecute is doing.
  • If you don't see TestExecute start in a session, double check your username variable in the pipeline.
• Run Agent Node as a windows service.
• Let service interact with the desktop.

GaryRogers

Replaying logs to logstash

• Copy comprssed log files to a work area.
• Uncompress them, remove date part of file name.
• Copy /etc/logstash/conf.d/*.conf to a work location.
• Modify conf files to change output to stdout { codev => "rubydebug" }
• You want to do this to make sure things are working before you push logs into ElasticSearch.
• Modify conf files to change path in the input/file section

GaryRogers

import dpath.util

def dpath_null(data: dict, path: str, default_return = None):
  '''function to trap any KeyErrors for dpath and return an acceptable 'null' value when dpath can't find a path

  Example 1
  ---------
  
  # Will return None if /some/path/to/an/attribute can not be found
  var = dpath_null(my_dictionary, '/some/path/to/an/attribute')