How to prepare your CentOS 7 machine to Microsoft Azure

This guide will help you prepare your CentOS 7 server for a migration from on-premise to Microsoft Azure cloud. It can be a bit tricky to get everything to work correctly and personally I didn’t find Microsofts guides to be great so I write this post to help you with the steps that is needed to migrate your old CentOS 7 machine to the cloud.

What you need to configure

  • Install Azure Linux Agent
  • Network Configuration
  • Hyper-V Drivers Configuration
  • Serial Console Configuration

How to do it

Install Azure Linux Agent

Install the Azure Linux Agent with yum.
yum install WaLinuxAgent

Network Configuration

The network interface needs to be configured to use DHCP and you need to add the hyper-v drivers to the interface. You can either do it by configuring your existing networki interface (eth0) or create a new one:

1. Create a configuration file for the interface
vim /etc/sysconfig/network-scripts/ifcfg-eth0

NAME="eth0"
DEVICE="eth0"
BOOTPROTO=dhcp
ONBOOT=yes


Save the file with :wq

2. Map the networking card to the Hyper-V drivers by appending the following line to the 70-persistent-net.rules file.

vim /etc/udev/rules.d/70-persistent-net.rules

#For Azure
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="hv_netvsc", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

Save the file with :wq

Hyper-V Drivers Configuration

  1. Add Hyper-V drivers to Dracut
    vim /etc/dracut.conf
    add_drivers+=" hv_vmbus hv_netvsc hv_storvsc nvme ena xen_blkfront xen_netfront mptbase mptscsih mptspi "
  2. Update Initramfs by running the following command:
    dracut --force -v
  3. Verify that the Hyper-V modules have been loaded
    lsinitrd | grep hv

Serial Console Configuration

Azure uses ttyS0 for serial connection so we need to add it to our configuration.

  1. First add ttyS0 to secureetty by appending the following
    vim /etc/secureetty
    #add
    ttyS0

  2. Configure grub
    vim /etc/default/grub
    #Add
    GRUB_CMDLINE_LINUX="rootdelay=300 console=ttyS0 earlyprintk=ttyS0"

    After saving the file run the following command
    grub2-mkconfig -o /boot/grub2/grub.cfg
  3. Activate serial service
    Copy, link and activate the serial-getty service for ttys0.

    Copy:
    cp /usr/lib/systemd/system/serial-getty@.service /etc/systemd/system/serial-getty@ttyS0.service

    Create a symlink:
    ln -s /etc/systemd/system/serial-getty@ttyS0.service /etc/systemd/system/getty.target.wants/

    Reload the daemon, then start and enable the service:
    systemctl daemon-reload
    systemctl start serial-getty@ttyS0.service
    systemctl enable serial-getty@ttyS0.service

Now you are ready for a migration to Microsoft Azure. I hope you found this guide helpful and that you will succeed with your cloud transformation.

Note: If you are running CentOS 6 I also have a guide for preparing your server for Azure.

// Rickard Carlsson

How to prepare your CentOS 6 machine to Microsoft Azure

CentOS 6 to Azure

This guide will help you prepare your CentOS 6 server for a migration from on-premise to Microsoft Azure cloud. It can be a bit tricky to get everything to work correctly and personally I didn’t find Microsofts guides to be great so I write this post to help you with the steps that is needed to migrate your old CentOS 6 machine to the cloud.

What you need to configure

  • Install Azure Linux Agent
  • Network Configuration
  • Hyper-V Drivers Configuration
  • Serial Console Configuration

How to do it

Install Azure Linux Agent

Note: You will probably need to fix mirror configuration since CentOS 6 is EOL. Instructions can be found on the following link.

  • Alternative 1
    yum install WaLinuxAgent
  • Alternative 2
    cd /tmp
    wget http://olcentgbl.trafficmanager.net/openlogic/6/openlogic/x86_64/RPMS/WALinuxAgent-2.2.45-1.el6.noarch.rpm
    yum localinstall WALinuxAgent-2.2.45-1.el6.noarch.rpm

Network Configuration

The network interface needs to be configured to use DHCP and you need to add the hyper-v drivers to the interface. You can either do it by configuring your existing networki interface (eth0) or create a new one:

1. Create a configuration file for the interface
vim /etc/sysconfig/network-scripts/ifcfg-eth0

NAME="eth0"
DEVICE="eth0"
BOOTPROTO=dhcp
ONBOOT=yes


Save the file with :wq

2. Map the networking card to the Hyper-V drivers by appending the following line to the 70-persistent-net.rules file.

vim /etc/udev/rules.d/70-persistent-net.rules

#For Azure
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="hv_netvsc", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

Save the file with :wq

Hyper-V Drivers Configuration

  1. Add Hyper-V drivers to Dracut

    vim /etc/dracut.conf

    add_drivers+=" hv_vmbus hv_netvsc hv_storvsc nvme ena xen_blkfront xen_netfront mptbase mptscsih mptspi "

  2. Update Initramfs by running the following command:

    dracut --force -v
  3. Verify that the Hyper-V modules have been loaded

    lsinitrd | grep hv

Serial Console Configuration

Azure uses ttyS0 for serial connection so we need to add it to our configuration.

  1. First add ttyS0 to secureetty by appending the following

    vim /etc/secureetty
    #add
    ttyS0

  2. Configure grub

    vim /boot/grub/grub.conf

    #add below configuration to kernel
    rootdelay=300 console=ttyS0 earlyprintk=ttyS0

    #also remove
    rhgb quiet crashkernel=auto
  3. Configure sysconfig/init

    vim /etc/sysconfig/init

    #Edit ACTIVE_CONSOLES to look like (make sure to use “”):
    ACTIVE_CONSOLES="/dev/tty[1-6] /dev/ttyS0"

    Also make sure to configure:
    timeout=15
    serial --unit=0 --speed=115200
    terminal --timeout=5 serial console

Now you are ready for a migration to Microsoft Azure. I hope you found this guide helpful and that you will succeed with your cloud transformation.

Note: If you are running CentOS 7 I also have a guide for preparing your server for Azure.

// Rickard Carlsson

Review – Terraform Associate Certification

In this blog post I will give my review on the latest certification I obtained, Hashicorp Terraform Associate. I will start by describing what Terraform is and then give you my take on how to study to pass this exam at your first attempt.

What is Infrastructure as Code (IaC)

If you are not familiar with the concept of IaC I would recommend you to watch this quick explanation.

What is Terraform

Terraform is an open-source software tool for IaC created by HashiCorp. The tool helps users to define and provision a cloud infra the Hashicorp Configuration Language (HCL), or optionally JSON. Three days ago they also released a CDK with Python and Typescript support. Terraform supports most of the big of cloud infrastructure providers.

Exam details

The exam is online based and you will be monitored by a proctor. To be able to do the exam you will need to have a webcam, speakers, a microphone and the zoom client installed.

  • Exam format: (Link to Sample questions)
    • Multiple Choice Questions (MCQs)
    • Multiple Answer Questions (MAQs)
    • True or False
    • Text match questions.
  • No of questions: 57
  • Exam duration: 1 hour
  • Exam cost: The website says $70.50 plus taxes, for me the total cost including taxes were around 90 euro which is very cheap compared to other certifications.

Study plan

In this section I will describe how I recommend that you study for this exam. When talking about certifications people always wonder how long time it takes to study for the exam. The answer to that question is the same as always, it depends on your background, your motivation to learn, how much time you can put into it and how easy you have to learn new stuff.

I had no prior knowledge of IaC before starting to study for this exam and I was able to learn the concepts to pass this exam in around two weeks. I have heard people saying that it is recommended to have 1-2 years of experience with Terraform before taking the exam but I don’t think that is necessary.

If you follow my study plan below I don’t think that you will have any problems with passing the exam.

  1. Official HashiCorp study material
    Begin by reading the official study guide.

    If you have some experience with Terraform and just want to fresh up your skills before the exam you can read the official exam review instead.

  2. Spin up a Lab environment
    I used Microsoft Azure for this since I’m familiar with Azure and the fact that Microsoft offer you a $200 credit to explore Azure for 30 days. I think that most cloud providers offer similar stuff so choose the cloud provider of your taste and spin up a lab environment.

    Installation guide and videos on how to get started are included in the study guide but here is a link directly to the installation video.

  3. Video courses combined with lab time
    My third recommendation is to watch some video courses. Learning from videos is my personal favorite and I really recommend that you watch the videos and try to follow the instructor in your own lab environment. The best video series I found online was on Youtube and it was created by Will Brock. Really awesome content that I highly recommend you to watch.
  1. Practice exams
    When you feel like you understand everything in the videos and have spent some hours in you lab environment I recommend you to do some practice exams so you get a feeling on how the questions will be structured on the real exam. I did some practice exams on Udemy after getting a free voucher from the creator. He shared it in the subreddit /r/Terraform so keep an eye there.

    I also found an awesome blog post by a guy named Bhargav Bachina. He goes through each of the exam objectives and have created practice questions based on the objectives. In total there are 250 questions. I really recommend you to read this one.

Summary

When you have completed the steps above you should be ready for the exam. I think that the exam was very fair and I would say that 60min is more than enough time. I think that I had around 20 minutes left when I pressed submit.

In summary I would say that Terraform is a really awesome tool and that the certification was fun. I hope you liked this post. If you have any questions, feel free to send me an email or contact me at twitter. (@tzusec)

// Rickard

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