Category Archives: Linux

The mysql.session exists but is not correctly configured

One of our MySQL server(5.5.x) crashed but fortunately we have setup the backup of it. I have built the new server with MySQL(5.7.34) and restored the backup on it but when I tried to run any query like creating new user(s) etc got an error something like:

ERROR 1728 (HY000): Cannot load from mysql.db. The table is probably corrupted

This happens due to the schema changes required for different MySQL server versions. The simple fix to this problem recommended by MySQL is to run the mysql_upgrade command from the command line.
mysql_upgrade checks all tables across all databases for incompatibilities with the current version of MySQL. mysql_upgrade also upgrades the system tables so that we can take advantage of new privileges or capabilities that might have been added. It supersedes the older mysql_fix_privilege_tables script, which should no longer be used.

[IMPORTANT NOTE] Before running mysql_upgrade command on production server, it’s always a good practice to take a full backup of all the databases first, just in case something goes wrong.

I tried to run mysql_upgrade command from terminal:

mysql_upgrade -uroot -p

After entering the command, got this error message:

Note: I am not mentioning mysql username and password in the command because I am using .my.cnf configuration

mysql_upgrade will perform a weaker verification. If the result is not equal to 1, then mysql_upgrade cannot be executed.

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Jenkins Installation and GitHub OAuth Integration using Ansible

In this tutorial, we’ll use Ansible to automate the installation of Jenkins CI on a fresh Ubuntu 14.04 LTS and integrate it with the GitHub OAuth. Ansible will also assign the matrix based permission on the Jenkins like which github user or group(s) have what rights on the Jenkins. Beside that, it will also install the Apache which serves as frontend for all the Jenkins requests.

In short, in this tutorial we’ll do the following tasks using Ansible:

  • Install the JAVA 7
  • Install the mentioned version of Jenkins(in this case it will be 1.658)
  • Install the desired plugins
  • Install the Apache and configure it as frontend for Jenkins
  • Install the SSL certificate for Apache Virtual Host that act as frontend for Jenkins
  • Integrate the Jenkins with GitHub using OAuth for Authenication
  • Configure the matrix based security using the github username or group

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Ansible role to create linux users with Github accounts ssh key

In this short tutorial we’ll learn how to create or delete the linux user accounts with public ssh keys associated with their Github accounts using Ansible, so please create a Github account if you don’t already have one, and follow the instructions for associated SSH keys with your account, if you didn’t perform it already.

First, download this Repository from the GitHub:

git clone

Note: If git is not installed then you can simply download the zip file.

Move inside the cloned directory:

cd ansible-roles

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How to compile a development version of Terraform

In this tutorial I’ll describe all the steps to build the development version of Terraform. At the end of this process, it will generate a set of binaries for each supported platforms(Linux, Mac OS X, Windows etc..).

First we need to clone the terraform’s github offical repo:

git clone

Move inside the cloned repo:

cd terraform

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Highly-Available WordPress Setup inside AWS VPC using Terraform & Ansible

In this post,we’ll create the Infrastructure for Highly-Available WordPress website over AWS using Terraform and then install the WordPress using Ansible. If you don’t know about the Terraform, please check this link.

We’ll use the Terraform to create the fully operational AWS VPC infrastructure(subnets,routeing tables,igw etc), it will also create everything that need to be for creating EC2 and RDS instances (security key, security group, subnet group). It will also create the Elastic Load Balancer and add the EC2 instance(s) automatically to it as well as creating the Route53 entry for this wordpress site and add the ELB alias to it.

Ansible will be used to deploy the wordpress on the EC2 instances that have been created via Terraform, that will be fault tolerant and highly available.


  • Terraform
  • Ansible
  • AWS admin access

Tools Used: Read more of this post

AWS Infrastructure Creation with Ansible Part-3

By this point, you should have already read the Part-1 and Part-2 of this series. In this tutorial, we’ll create the EC2 instances inside the VPC that we have created in Part-1, Security Group & EC2 Key Pair created in Part-2 and also add them inside the ELB, all with Ansible.

If you have completed the previous parts of this series, then you have already clone the git repo that contains all the roles, if not then clone the git repo:

git clone
 cd ansible-aws-roles

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AWS Infrastructure Creation with Ansible Part-2

In the second part of this series of tutorials, we’ll create the Security Group and EC2 Key Pair using Ansible. If you didn’t create the VPC already, then please check the Part-1 of this series.

If you have completed the Part-1, then you have already clone the git repo that contains all the roles, if not then clone the git repo:

git clone
cd ansible-aws-roles

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AWS Infrastructure Creation with Ansible Part-1

In this series of posts, we’ll create the Infrastructure over AWS using Ansible. For the first part of this series, we’ll create the VPC, the basic building block, because everything like Security Group, EC2 instance, RDS Instance, ELB etc will create inside the VPC.

Requirement to use these roles:

- Ansible v2.0
- boto
- AWS admin access

Specifically, these are the versions of mentioned software that I am using for this series:


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AWSCli Installation & Configuration using Ansible

In this blog post, we’ll learn that how we can use simple Ansible role to install the AWS CLI with all the required dependencies on Ubuntu 14.04 LTS, it should work on other versions of Ubuntu too.

First, clone this Repository from the GitHub:

git clone

Note: If git is not installed then you can simply download the zip file.

To use this role, edit the site.yml file:

vi site.yml

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Install OpenVPN server using Ansible over AWS VPC

In this tutorial, we’ll use this blog post as a base and use the below scenario in which we’ll configure the custom NAT instance to OpenVPN as well using Ansible to access the resources inside the private subnet(s).


Please modify the following things for the above mentioned post:

– Open the UDP port 1194 inside the NAT instance Security Group

– Allow the desired traffic inside the desired desination server(s) Security Group for NAT instance

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