How to change root password on Debian – after vacation


Since i had a vacation and completely forgot all my passwords for Debian VM i fixed it using this article. Very useful!


kafka linux

Ubuntu – change ulimit for kafka, do not ignore


Wanna share with you what managed to take me half a day to clarify. I just read in the following article
and learned that in order to optimize kafka, you will need to also change the maximum number of open files. It is nice, but our clusters are deployed on Ubuntu and the images are pretty basic. Not really sure if this is valid for all of the distributions but at least for this one it’s absolutely needed.
Before trying to setup anything in


make sure that you have exported in



session required

It is needed in order for ssh, su processes to take the new limits for that user (in our case kafka).
Doing this will help you define new values on “limits” file. You are now free to setup nofile limit like this for example

*               soft    nofile          10000
*		hard	nofile		100000
kafka		soft 	nofile		10000
kafka		hard	nofile		100000

After it is done, you can restart the cluster and check value by finding process with ps-ef | grep kafka and viewing limit file using cat /proc/[kafka-process]/limits.

I will come back later with also a puppet implementation for this.



Python dictionary construction from process list


This is out of my expertise but i wanted to shared it anyways. One colleague wanted to help him with the creation of a pair key:value from one command that lists the processes, in python. With a little bit of testing i came to the following form:

import os
import subprocess
from subprocess import Popen, PIPE
username = subprocess.Popen(['/bin/ps','-eo','pid,uname'], stdout=PIPE, stderr=PIPE)
firstlist ='\n')
dict = {}
for str in firstlist:
  if (str != ''):
    secondlist = str.split()
    key = secondlist[0]
    value = secondlist[1]

Now, i think there are better ways to write this but it works also in this way.
If you find better ways, please leave a message ūüôā


kafka linux puppet

Securing kafka-manager endpoints with iptables rules behind traefik


One extra addition to my traefik balancing article from is that even so now we have the balancing capability we still need to restrict access to unsecured endpoint. I thought all the code to be deployable on all of the nodes. If this is taken in consideration, our issue with the firewall rules should be easily solved by using the puppetlabs module and the code that i included looks like:

$hosts_count = $kafka_hosts.count
  package {'iptables-persistent':
  name => 'iptables-persistent',
  ensure => installed,
  resources { 'firewall':
    purge => true,
  $kafka_hosts.each | Integer $index,String $host | {
    firewall {"10${index} adding tcp rule kafka manager node ${index}":
      proto => 'tcp',
      dport => 9000,
      source => "${host}",
      destination => "${fqdn}",
      action => 'accept',
  firewall {"10${hosts_count} droping rest of kafka manager calls":
    proto => 'tcp',
      dport => 9000,
      destination => "${fqdn}",
      action => 'drop',

This should be add rules in order to allow traffic on port 9000 only between the kafka hosts that have kafka manager installed.


Small Mirror Maker test between different Kafka clusters


Today i am trying to show you what i have been playing with for the last day. There was a business case in which some colleagues from Analytics wanted to replicate all the data from other systems in their cluster.

We will start with this, two independent configured clusters with 3 servers each (on each server we have one zookeeper and one kafka node). On both the source and target i created a topic replicated three times with five partitions. You can find the description

/opt/kafka/bin/ --zookeeper localhost:2181 --describe --topic test-topic
Topic:test-topic	PartitionCount:5	ReplicationFactor:3	Configs:
	Topic: test-topic	Partition: 0	Leader: 1002	Replicas: 1002,1003,1001	Isr: 1002,1003,1001
	Topic: test-topic	Partition: 1	Leader: 1003	Replicas: 1003,1001,1002	Isr: 1003,1001,1002
	Topic: test-topic	Partition: 2	Leader: 1001	Replicas: 1001,1002,1003	Isr: 1001,1002,1003
	Topic: test-topic	Partition: 3	Leader: 1002	Replicas: 1002,1001,1003	Isr: 1002,1001,1003
	Topic: test-topic	Partition: 4	Leader: 1003	Replicas: 1003,1002,1001	Isr: 1003,1002,1001

The command for creating this is actually pretty simple and it goes like this¬†/opt/kafka/bin/ –zookeeper localhost:2181 –create –replication-factor 3 –partition 5 –topic test-topic

Once the topic are created on both kafka instances we will need to start Mirror Maker (HortonWorks recommends that the process should be created on the destination cluster). In order to do that, we will need to create two config files on the destination. You can call them producer.config and consumer.config.

For the consumer.config we have the following structure:


For the producer.config we have the following structure:


These are the principal requirements and also you will need to be sure that you have in you the following line

Ok, so far so good, now lets start Mirror Maker with and once started you can see it beside kafka and zookeeper using ps -ef | grep java

/opt/kafka/bin/ --consumer.config ../config/consumer.config --producer.config ../config/producer.config --whitelist test-topic &

To check the offset, at new versions of kafka you can always use

/opt/kafka/bin# ./ kafka.admin.ConsumerGroupCommand --group test-consumer-group --bootstrap-server localhost:9092 --describe
GROUP                          TOPIC                          PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG             OWNER
test-consumer-group            test-topic                     0          2003            2003            0               test-consumer-group-0_/[dest_ip]
test-consumer-group            test-topic                     1          2002            2002            0               test-consumer-group-0_/[dest_ip]
test-consumer-group            test-topic                     2          2003            2003            0               test-consumer-group-0_/[dest_ip]
test-consumer-group            test-topic                     3          2004            2004            0               test-consumer-group-0_/[dest_ip]
test-consumer-group            test-topic                     4          2002            2002            0               test-consumer-group-0_/[dest_ip]

I tested the concept by running a short loop in bash to create 10000 records and put them to a file¬†for i in $( seq 1 10000); do echo $i; done >> test.txt¬†¬†and this can be very easily imported on our producer by running the command¬†/opt/kafka/bin/ –broker-list localhost:9092 –topic test-topic < test.txt

After this is finished, please feel free to take a look in the topic using /opt/kafka/bin/ –bootstrap-server localhost:9092 –topic test-topic –from-beginning¬†and you should see a lot of lines ūüôā

Thank you for your time and if there are any parts that i missed, please reply.



Check Kafka JMX node stats using JConsole


As you probably know, Kafka is already publishing a lot of performance data on JMX to be collected.
In order to do this, you will need to install jconsole (for Windows it’s already embedded in the jdk installation, for Linux you can use this article to check it out¬† After you have done that, you will have just to export the JMX_PORT variable to you env (for example export JMX_PORT=9999) before you start the Kafka node. When you will open JConsole you will probably see something like

After you select the Kafka node, it will tell you that the connection is not secure, but it doesn’t matter for my point of view and after that you can have a overview of the process. The statistics are available MBens tab and extra info regarding the meaning you can find in the official doku¬†and also in the DataDog article.

This is a single simple node configuration, if it is required i will post some complex configurations, but this is required in special cases, standard monitoring using DataDog/Prometheus or other solution needs to be implemented in case of a bigger infrastructure.


cloud newtools

Small Vagrant config file for Rancher deploy


Just wanted to post this also, if it’s not that nice the config using a jumpserver, surely we can convert that to code (Puppet/Ansible), you can also use Vagrant. The main issue that i faced when i tried to create my setup is that for a reason (not really sure why, Vagrant on Windows runs very slow). However, i chose to give you one piece of Vagrantfile for a minimal setup on which you can grab the Rancher server framework and also the client containers.

Here is it:

# -*- mode: ruby -*-
# vi: set ft=ruby :
Vagrant.configure("2") do |config|
config.vm.define "master" do |master| = "centos/7"
master.vm.hostname = 'master' "public_network", bridge: "enp0s25"
config.vm.define "slave" do |slave| = "centos/7"
slave.vm.hostname = 'slave' "public_network", bridge: "enp0s25"
config.vm.define "swarmmaster" do |swarmmaster| = "centos/7"
swarmmaster.vm.hostname = 'swarmmaster' "public_network", bridge: "enp0s25"
config.vm.define "swarmslave" do |swarmclient| = "centos/7"
swarmclient.vm.hostname = 'swarmclient' "public_network", bridge: "enp0s25"


Do not worry about the naming of the machines, you can change them to whatever you like, the main catch is to bridge the public network in all of them in order to be able to communicate with each other and also have access to the docker hub. Beside that everything else that i posted regarding the registry to the Rancher framework is still valid.

Thank you for your time,



Memory check by process in Linux


I wanted to post this since it might be useful in some situations. On a Linux machine it seems that one way to check the memory usage by top processes is with ps aux –sort -rss (This means that it’s order by Resistent Set Size)¬†¬†Once executed it will return an output similar to this:

sorin 3673 0.6 27.3 3626020 563964 pts/1 Sl+ 02:24 1:09 java -Xmx1G -Xms1G -server -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:+Disa
sorin 1708 2.0 9.2 1835288 189692 ? Sl 02:11 3:56 /usr/bin/gnome-shell
sorin 1967 0.6 8.0 1642280 166160 ? Sl 02:12 1:11 firefox-esr
sorin 3413 0.1 3.7 2000252 77016 pts/0 Sl+ 02:21 0:19 java -Xmx512M -Xms512M -server -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:+
root 576 0.5 2.6 263688 54172 tty7 Ssl+ 02:11 1:07 /usr/bin/Xorg :0 -novtswitch -background none -noreset -verbose 3 -auth /var/run/gdm3/auth-for-Debian-gdm-Bu1jB
sorin 1813 0.0 2.2 1175504 47196 ? Sl 02:11 0:00 /usr/lib/evolution/evolution-calendar-factory
root 486 0.1 1.2 377568 26584 ? Ssl 02:11 0:21 /usr/bin/dockerd -H fd://

If you want to get more detail of a PID status you can go to /proc/[pid]/status and you can find a lot of other informations. For example the top process on my Linux machine has the following header:

sorin@debian:/proc/3673$ cat status
Name: java
State: S (sleeping)
Tgid: 3673
Ngid: 0
Pid: 3673
PPid: 3660
TracerPid: 0
Uid: 1000 1000 1000 1000
Gid: 1000 1000 1000 1000
FDSize: 256
Groups: 24 25 29 30 44 46 108 111 116 1000
VmPeak: 3626024 kB
VmSize: 3626020 kB

As you can see, the RSS is the same as VmSize.



Register RancherOs to the Rancher framework


After we were able to login via ssh on our machines, it’s time to put them to use by subscribing them to a orchestrating framework. One free and pretty powerful framework of such kind is given by the same company. In order to use it you will need to have Docker installed, more info on this topic following the link

Until now i haven’t tried the option for a HA configuration, i will do that in the near future and post the findings but for now it should be enough if we deploy a standard container for the management.

Using the command from the documentation i have managed to grab the image and start the following container:

417930c9f375 rancher/server "/usr/bin/entry /u..." 2 weeks ago Up 6 minutes 3306/tcp,>8080/tcp eloquent_goodall

We have also the possibility to check the image using the docker images  command and we will have the following result:

rancher/server latest 2751db6ea7ec 4 weeks ago 935 MB

Once the container is started, you can access the UI by going to the address (please keep in mind that you have binded the ports to be forwarded and accessible from any IP range, that is what>8080/tcp should mean, if you want to be accessible for a specific range or IP please change this on docker run command.

Ok, once the administration console has been loaded you can go to Infrastructure -> Hosts -> Add Host. Please do not use the default site address, it is relevant only for the local container, instead it can be replaced by  http://[jumpserver ip address]:8080. This will be used in order to obtain the registration string for the agents. When pressing OK, you will be redirected to a window with the necessary steps to be done for registration, please keep it open.

After connecting via ssh to the Rancher machine, please make sure that you have access to the Docker hub repo. You can easily do that by running docker search rancher. If there is a timeout error, please take a look on configuring proxy for docker, in our case on private machines it can be done using the following lines in cloud-config.yml located under /var/lib/rancher/conf

http_proxy: http://[user]:[password]@[proxyip]:[proxyport]
https_proxy: http://[user]:[password]@[proxyip]:[proxyport]

These lines being added you will need to reload the docker daemon by using the command system-docker restart docker and it should work.

Now go to the UI page and copy the string at the last step in our Rancher server window, it will start downloading the necessary containers in order to link with the framework.

This being done some images will be downloaded and started to the machine and started:

[rancher@rancher conf]$ docker images | grep rancher
rancher/scheduler v0.7.5 e7ff16ba4444 2 weeks ago 241.9 MB
rancher/network-manager v0.5.3 0f224908d730 2 weeks ago 241.6 MB
rancher/metadata v0.8.11 19b37bb3e242 5 weeks ago 251.5 MB
rancher/agent v1.2.1 9cecf992679f 5 weeks ago 233.7 MB
rancher/scheduler v0.7.4 7a32d7571cad 5 weeks ago 241.9 MB
rancher/net v0.9.4 5ac4ae5d7fa4 5 weeks ago 264.3 MB
rancher/network-manager v0.4.8 45bdcd2b1944 6 weeks ago 241.6 MB
rancher/dns v0.14.1 4e37fc4150c2 6 weeks ago 239.8 MB
rancher/healthcheck v0.2.3 491349141109 10 weeks ago 383.3 MB
rancher/net holder bb516596ce5a 3 months ago 261.7 MB
[rancher@rancher conf]$ docker ps -a | grep rancher
a3fde18ebdbd rancher/scheduler:v0.7.5 "/.r/r /rancher-entry" 3 days ago Exited (0) 3 days ago r-scheduler-scheduler-1-37fd65ec
35c7bbc1cb42 rancher/network-manager:v0.5.3 "/rancher-entrypoint." 3 days ago Up 30 minutes r-network-services-network-manager-1-57e1bbbd
3a048010be3d rancher/scheduler:v0.7.4 "/.r/r /rancher-entry" 2 weeks ago Exited (0) 3 days ago r-scheduler-scheduler-1-de6ec66f
fad7d11141aa rancher/net:v0.9.4 "/rancher-entrypoint." 2 weeks ago Up 29 minutes r-ipsec-ipsec-router-1-af053a8c
b7ce7b4f8520 rancher/dns:v0.14.1 "/rancher-entrypoint." 2 weeks ago Up 30 minutes r-network-services-metadata-dns-1-438fbeaa
30e5cab4b4c6 rancher/metadata:v0.8.11 "/rancher-entrypoint." 2 weeks ago Up 30 minutes r-network-services-metadata-1-827c71e3
382ebf55c3c1 rancher/net:holder "/.r/r /rancher-entry" 2 weeks ago Up 30 minutes r-ipsec-ipsec-1-55aeea30
0223f1ffe986 rancher/healthcheck:v0.2.3 "/.r/r /rancher-entry" 2 weeks ago Up 30 minutes r-healthcheck-healthcheck-1-f00a6858
03652d781c9a rancher/net:v0.9.4 "/rancher-entrypoint." 2 weeks ago Up 30 minutes r-ipsec-ipsec-cni-driver-1-797e0060
1b6d1664c801 rancher/agent:v1.2.1 "/ run" 2 weeks ago Up 31 minutes rancher-agent
c8b8e4ddf91c rancher/agent:v1.2.1 "/ http://10.0." 2 weeks ago Exited (0) 2 weeks ago furious_bohr

And also the server will appear in the UI. In next posts we will try to deploy some services from the catalog.