Merge pull request #232430 from msaenzbosupport/patch-4

[DOC-a-THON]  Updating Centos upload VHD

Author: v-dirichards

articles/virtual-machines/linux/create-upload-centos.md

@@ -26,20 +26,23 @@ This article assumes that you've already installed a CentOS (or similar derivati
 **CentOS installation notes**
 
 * For more tips on preparing Linux for Azure, see [General Linux Installation Notes](create-upload-generic.md#general-linux-installation-notes).
-* The VHDX format isn't supported in Azure, only **fixed VHD**.  You can convert the disk to VHD format using Hyper-V Manager or the convert-vhd cmdlet. If you're using VirtualBox this means selecting **Fixed size** as opposed to the default dynamically allocated when creating the disk.
+* The VHDX format isn't supported in Azure, only **fixed VHD**.  You can convert the disk to VHD format using Hyper-V Manager or the convert-vhd cmdlet. If you're using VirtualBox, this means selecting **Fixed size** as opposed to the default dynamically allocated when creating the disk.
 * The vfat kernel module must be enabled in the kernel
-* When installing the Linux system it's *recommended* that you use standard partitions rather than LVM (often the default for many installations). This will avoid LVM name conflicts with cloned VMs, particularly if an OS disk ever needs to be attached to another identical VM for troubleshooting. [LVM](/previous-versions/azure/virtual-machines/linux/configure-lvm) or [RAID](/previous-versions/azure/virtual-machines/linux/configure-raid) may be used on data disks.
+* When installing the Linux system it's **recommended** that you use standard partitions rather than LVM (often the default for many installations). This avoids LVM name conflicts with cloned VMs, particularly if an OS disk ever needs to be attached to another identical VM for troubleshooting. [LVM](/previous-versions/azure/virtual-machines/linux/configure-lvm) or [RAID](/previous-versions/azure/virtual-machines/linux/configure-raid) may be used on data disks.
 * **Kernel support for mounting UDF file systems is necessary.** At first boot on Azure the provisioning configuration is passed to the Linux VM by using UDF-formatted media that is attached to the guest. The Azure Linux agent or cloud-init  must mount the UDF file system to read its configuration and provision the VM.
-* Linux kernel versions below 2.6.37 don't support NUMA on Hyper-V with larger VM sizes. This issue primarily impacts older distributions using the upstream Red Hat 2.6.32 kernel, and was fixed in RHEL 6.6 (kernel-2.6.32-504). Systems running custom kernels older than 2.6.37, or RHEL-based kernels older than 2.6.32-504 must set the boot parameter `numa=off` on the kernel command-line in grub.conf. For more information see Red Hat [KB 436883](https://access.redhat.com/solutions/436883).
-* don't configure a swap partition on the OS disk. More information about this can be found in the steps below.
-* All VHDs on Azure must have a virtual size aligned to 1MB. When converting from a raw disk to VHD you must ensure that the raw disk size is a multiple of 1MB before conversion. See [Linux Installation Notes](create-upload-generic.md#general-linux-installation-notes) for more information.
+* Linux kernel versions below 2.6.37 don't support NUMA on Hyper-V with larger VM sizes. This issue primarily impacts older distributions using the upstream Centos 2.6.32 kernel, and was fixed in Centos 6.6 (kernel-2.6.32-504). Systems running custom kernels older than 2.6.37, or RHEL-based kernels older than 2.6.32-504 must set the boot parameter `numa=off` on the kernel command-line in grub.conf. For more information, see Red Hat [KB 436883](https://access.redhat.com/solutions/436883).
+* Don't configure a swap partition on the OS disk.
+* All VHDs on Azure must have a virtual size aligned to 1 MB. When converting from a raw disk to VHD, you must ensure that the raw disk size is a multiple of 1 MB before conversion. See [Linux Installation Notes](create-upload-generic.md#general-linux-installation-notes) for more information.
 
 > [!NOTE]
 > **(_Cloud-init >= 21.2 removes the udf requirement._)** however without the udf module enabled the cdrom will not mount during provisioning preventing custom data from being applied. A workaround for this would be to apply custom data using user data however, unlike custom data user data isn't encrypted. https://cloudinit.readthedocs.io/en/latest/topics/format.html
 
 
 ## CentOS 6.x
 
+> [!IMPORTANT]
+>Please note that CentOS 6 has reached its End Of Life (EOL) and is no longer supported by the CentOS community. This means that no further updates or security patches will be released for this version, leaving it vulnerable to potential security risks. We strongly recommend upgrading to a more recent version of CentOS to ensure the safety and stability of your system. Please consult with your IT department or system administrator for further assistance.
+
 1. In Hyper-V Manager, select the virtual machine.
 
 2. Click **Connect** to open a console window for the virtual machine.
@@ -52,14 +55,14 @@ This article assumes that you've already installed a CentOS (or similar derivati
 
 4. Create or edit the file `/etc/sysconfig/network` and add the following text:
 
-    ```console
+    ```output
     NETWORKING=yes
     HOSTNAME=localhost.localdomain
     ```
 
 5. Create or edit the file `/etc/sysconfig/network-scripts/ifcfg-eth0` and add the following text:
 
-    ```console
+    ```output
     DEVICE=eth0
     ONBOOT=yes
     BOOTPROTO=dhcp
@@ -76,15 +79,15 @@ This article assumes that you've already installed a CentOS (or similar derivati
     sudo rm -f /etc/udev/rules.d/70-persistent-net.rules
     ```
 
-7. Ensure the network service will start at boot time by running the following command:
+7. Ensure the network service starts at boot time by running the following command:
 
     ```bash
     sudo chkconfig network on
     ```
 
-8. If you would like to use the OpenLogic mirrors that are hosted within the Azure datacenters, then replace the `/etc/yum.repos.d/CentOS-Base.repo` file with the following repositories.  This will also add the **[openlogic]** repository that includes additional packages such as the Azure Linux agent:
+8. If you would like to use the OpenLogic mirrors that are hosted within the Azure datacenters, then replace the `/etc/yum.repos.d/CentOS-Base.repo` file with the following repositories.  This will also add the **[openlogic]** repository that includes extra packages such as the Azure Linux agent:
 
-   ```console
+   ```output
    [openlogic]
    name=CentOS-$releasever - openlogic packages for $basearch
    baseurl=http://olcentgbl.trafficmanager.net/openlogic/$releasever/openlogic/$basearch/
@@ -138,14 +141,14 @@ This article assumes that you've already installed a CentOS (or similar derivati
 
 9. Add the following line to /etc/yum.conf:
 
-	```console
+	```output
 	http_caching=packages
 	```
 
 10. Run the following command to clear the current yum metadata and update the system with the latest packages:
 
 	```bash
-	yum clean all
+	sudo yum clean all
 	```
 
     Unless you're creating an image for an older version of CentOS, it's recommended to update all the packages to the latest:
@@ -177,34 +180,34 @@ This article assumes that you've already installed a CentOS (or similar derivati
 	```
 
 
-    The WALinuxAgent package will remove the NetworkManager and NetworkManager-gnome packages if they were not already removed as described in step 3.
+    The WALinuxAgent package removes the NetworkManager and NetworkManager-gnome packages if they were not already removed as described in step 3.
 
 13. Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this, open `/boot/grub/menu.lst` in a text editor and ensure that the default kernel includes the following parameters:
 
-	```console
+	```output
 	console=ttyS0 earlyprintk=ttyS0 rootdelay=300
 	```
 
     This will also ensure all console messages are sent to the first serial port, which can assist Azure support with debugging issues.
 
     In addition to the above, it's recommended to *remove* the following parameters:
 
-	```console
+	```output
 	rhgb quiet crashkernel=auto
 	```
 
-    Graphical and `quiet boot` are not useful in a cloud environment where we want all the logs to be sent to the serial port.  The `crashkernel` option may be left configured if desired, but note that this parameter will reduce the amount of available memory in the VM by 128MB or more, which may be problematic on the smaller VM sizes.
+    Graphical and `quiet boot` aren't useful in a cloud environment where we want all the logs to be sent to the serial port.  The `crashkernel` option may be left configured if desired, but note that this parameter will reduce the amount of available memory in the VM by 128 MB or more, which may be problematic on the smaller VM sizes.
 
     > [!Important]
     > CentOS 6.5 and earlier must also set the kernel parameter `numa=off`. See Red Hat [KB 436883](https://access.redhat.com/solutions/436883).
 
 14. Ensure that the SSH server is installed and configured to start at boot time.  This is usually the default.
 
-15. don't create swap space on the OS disk.
+15. Don't create swap space on the OS disk.
 
-    The Azure Linux Agent can automatically configure swap space using the local resource disk that is attached to the VM after provisioning on Azure. Note that the local resource disk is a *temporary* disk, and might be emptied when the VM is deprovisioned. After installing the Azure Linux Agent (see previous step), modify the following parameters in `/etc/waagent.conf` appropriately:
+    The Azure Linux Agent can automatically configure swap space using the local resource disk that is attached to the VM after provisioning on Azure. The local resource disk is a *temporary* disk, and might be emptied when the VM is deprovisioned. After installing the Azure Linux Agent (see previous step), modify the following parameters in `/etc/waagent.conf` appropriately:
 
-	```console
+	```output
 	ResourceDisk.Format=y
 	ResourceDisk.Filesystem=ext4
 	ResourceDisk.MountPoint=/mnt/resource
@@ -214,11 +217,13 @@ This article assumes that you've already installed a CentOS (or similar derivati
 
 16. Run the following commands to deprovision the virtual machine and prepare it for provisioning on Azure:
 
-	```bash
-	sudo waagent -force -deprovision+user
-	export HISTSIZE=0
-	logout
-	```
+    ```bash
+    sudo waagent -force -deprovision+user
+    sudo export HISTSIZE=0
+    ```
+> [!NOTE]
+> If you are migrating a specific virtual machine and do not wish to create a generalized image, skip the deprovision step.
+
 
 17. Click **Action -> Shut Down** in Hyper-V Manager. Your Linux VHD is now ready to be [uploaded to Azure](./upload-vhd.md#option-1-upload-a-vhd).
 
@@ -227,14 +232,14 @@ This article assumes that you've already installed a CentOS (or similar derivati
 
 **Changes in CentOS 7 (and similar derivatives)**
 
-Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, however there are several important differences worth noting:
+Preparing a CentOS 7 virtual machine for Azure is similar to CentOS 6, however there are several important differences worth noting:
 
 * The NetworkManager package no longer conflicts with the Azure Linux agent. This package is installed by default and we recommend that it'sn't removed.
 * GRUB2 is now used as the default bootloader, so the procedure for editing kernel parameters has changed (see below).
 * XFS is now the default file system. The ext4 file system can still be used if desired.
-* Since CentOS 8 Stream and newer no longer include `network.service` by default, you will need to install it manually:
+* Since CentOS 8 Stream and newer no longer include `network.service` by default, you need to install it manually:
 
-	```console
+	```bash
 	sudo yum install network-scripts
 	sudo systemctl enable network.service
 	```
@@ -247,14 +252,14 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
 3. Create or edit the file `/etc/sysconfig/network` and add the following text:
 
-	```console
+	```output
 	NETWORKING=yes
 	HOSTNAME=localhost.localdomain
 	```
 
 4. Create or edit the file `/etc/sysconfig/network-scripts/ifcfg-eth0` and add the following text:
 
-	```console
+	```output
 	DEVICE=eth0
 	ONBOOT=yes
 	BOOTPROTO=dhcp
@@ -273,7 +278,7 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
 6. If you would like to use the OpenLogic mirrors that are hosted within the Azure datacenters, then replace the `/etc/yum.repos.d/CentOS-Base.repo` file with the following repositories.  This will also add the **[openlogic]** repository that includes packages for the Azure Linux agent:
 
-   ```console
+   ```output
    [openlogic]
    name=CentOS-$releasever - openlogic packages for $basearch
    baseurl=http://olcentgbl.trafficmanager.net/openlogic/$releasever/openlogic/$basearch/
@@ -332,17 +337,17 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
 8. Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this, open `/etc/default/grub` in a text editor and edit the `GRUB_CMDLINE_LINUX` parameter, for example:
 
-	```console
+	```output
 	GRUB_CMDLINE_LINUX="rootdelay=300 console=ttyS0 earlyprintk=ttyS0 net.ifnames=0"
 	```
 
    This will also ensure all console messages are sent to the first serial port, which can assist Azure support with debugging issues. It also turns off the new CentOS 7 naming conventions for NICs. In addition to the above, it's recommended to *remove* the following parameters:
 
-	```console
+	```output
 	rhgb quiet crashkernel=auto
 	```
 
-    Graphical and quiet boot are not useful in a cloud environment where we want all the logs to be sent to the serial port. The `crashkernel` option may be left configured if desired, but note that this parameter will reduce the amount of available memory in the VM by 128MB or more, which may be problematic on the smaller VM sizes.
+    Graphical and quiet boot isn't useful in a cloud environment where we want all the logs to be sent to the serial port. The `crashkernel` option may be left configured if desired, but note that this parameter will reduce the amount of available memory in the VM by 128 MB or more, which may be problematic on the smaller VM sizes.
 
 9. Once you're done editing `/etc/default/grub` per above, run the following command to rebuild the grub configuration:
 
@@ -360,7 +365,7 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
     Edit `/etc/dracut.conf`, add content:
 
-	```console
+	```output
 	add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
 	```
 
@@ -379,22 +384,25 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
 12. Install cloud-init to handle the provisioning
 
-    ```console
-    yum install -y cloud-init cloud-utils-growpart gdisk hyperv-daemons
-
-    # Configure waagent for cloud-init
-    sed -i 's/Provisioning.Agent=auto/Provisioning.Agent=auto/g' /etc/waagent.conf
-    sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
-    sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf
-        
-    echo "Adding mounts and disk_setup to init stage"
-    sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
-    sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
-    sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
-    sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg
-
-    echo "Allow only Azure datasource, disable fetching network setting via IMDS"
-    cat > /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg <<EOF
+    ```bash
+    sudo yum install -y cloud-init cloud-utils-growpart gdisk hyperv-daemons
+    ```
+    1. Configure waagent for cloud-init
+    ```bash
+    sudo sed -i 's/Provisioning.Agent=auto/Provisioning.Agent=auto/g' /etc/waagent.conf
+    sudo sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
+    sudo sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf
+    ```
+    ```bash    
+    sudo echo "Adding mounts and disk_setup to init stage"
+    sudo sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
+    sudo sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
+    sudo sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
+    sudo sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg
+    ```
+    ```bash
+    sudo echo "Allow only Azure datasource, disable fetching network setting via IMDS"
+    sudo cat > /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg <<EOF
     datasource_list: [ Azure ]
     datasource:
         Azure:
@@ -415,7 +423,6 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
     # there without needing to look on the console.
     output: {all: '| tee -a /var/log/cloud-init-output.log'}
     EOF
-
     ```
 
 
@@ -425,18 +432,18 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
     Previously, the Azure Linux Agent was used to automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. However this is now handled by cloud-init, you **must not** use the Linux Agent to format the resource disk create the swap file, modify the following parameters in `/etc/waagent.conf` appropriately:
 
-    ```console
-    sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
-    sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf
+    ```bash
+    sudo sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
+    sudo sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf
     ```
 
     If you want mount, format and create swap you can either:
     * Pass this in as a cloud-init config every time you create a VM
     * Use a cloud-init directive baked into the image that will do this every time the VM is created:
 
-        ```console
-        echo 'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"' >> /etc/systemd/system.conf	
-        cat > /etc/cloud/cloud.cfg.d/00-azure-swap.cfg << EOF
+        ```bash
+        sudo echo 'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"' >> /etc/systemd/system.conf	
+        sudo cat > /etc/cloud/cloud.cfg.d/00-azure-swap.cfg << EOF
         #cloud-config
         # Generated by Azure cloud image build
         disk_setup:
@@ -457,15 +464,15 @@ Preparing a CentOS 7 virtual machine for Azure is very similar to CentOS 6, howe
 
 14. Run the following commands to deprovision the virtual machine and prepare it for provisioning on Azure:
 
-     **Note:** if you're migrating a specific virtual machine and don't wish to create a generalized image, skip the deprovision step
+    > [!NOTE]
+    > If you are migrating a specific virtual machine and don't wish to create a generalized image, skip the deprovision step.    
 
-	```console
-	# sudo rm -f /var/log/waagent.log
-	# sudo cloud-init clean
-	# waagent -force -deprovision+user
-	# rm -f ~/.bash_history
-	# export HISTSIZE=0
-	# logout
+	```bash
+	sudo rm -f /var/log/waagent.log
+	sudo cloud-init clean
+	sudo waagent -force -deprovision+user
+	sudo rm -f ~/.bash_history
+	sudo export HISTSIZE=0
 	```
 
 15. Click **Action -> Shut Down** in Hyper-V Manager. Your Linux VHD is now ready to be [uploaded to Azure](./upload-vhd.md#option-1-upload-a-vhd).