Elastic Compute Service:CentOS operating system

Replace or upgrade the operating system

Step 1: Choose a target operating system

Before you migrate or replace your operating system, select a Linux operating system to replace CentOS based on factors such as security compliance, stability, operating system compatibility, budget, and long-term strategy.

Step 2: Preparations

Before you perform a migration or replacement, complete the following preparations:

• Application testing: Create a staging environment with the target operating system. Deploy your applications and perform comprehensive functional, performance, and compatibility testing. Ensure that all business logic works correctly in the new environment.

• Migration drill: Rehearse your chosen migration solution in a non-production environment to familiarize yourself with the process and potential issues. For more information, see Troubleshooting Linux operating system migration issues.

• Plan a migration window: During the migration process, the system kernel and software packages of the original instance are updated, and the instance is restarted multiple times. Your services will be unavailable during this period. Assess the impact and plan a suitable migration window to avoid business disruptions.

Step 3: Perform the operating system migration

Which operating systems can I migrate CentOS to?

Operating systems that are binary-compatible with CentOS

A binary-compatible OS lets you run your existing applications and software immediately after migration without needing to recompile them. Migrating to a CentOS-compatible operating system does not guarantee bug-for-bug compatibility. You must consult the community support documentation for the target operating system to resolve any related issues.

Other operating systems

How do I convert CentOS 7 to Red Hat Enterprise Linux (RHEL) 7?

The following procedure describes how to manually convert CentOS 7 to RHEL 7 by running commands on the instance. To automate these steps, you can use the operating system migration feature.

How do I switch repository addresses for CentOS 6 after EOL?

The content at the CentOS 6 repository address http://mirror.centos.org/centos-6/ has been removed. Third-party mirror sites have also removed their CentOS 6 repositories. Alibaba Cloud's repositories at http://mirrors.cloud.aliyuncs.com and http://mirrors.aliyun.com can no longer synchronize with the CentOS 6 repository. Continuing to use the default CentOS 6 repository configuration on Alibaba Cloud results in an error. An example of the error is shown below:

Solutions

1. Log on to the ECS instance.

   1. Go to the ECS console - Instances page. In the top-left corner, select the resource group and region where your target resource is located.

   2. Navigate to the details page of the target instance, click Remote Connection, and select Connect via Workbench. Follow the prompts to log on and access the terminal.

2. Switch the yum repository.

   sudo vim /etc/yum.repos.d/CentOS-Base.repo 

   Press i to enter edit mode and replace the content with the following.

   [base]
   name=CentOS-6.10
   enabled=1
   failovermethod=priority
   baseurl=http://mirrors.cloud.aliyuncs.com/centos-vault/6.10/os/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.cloud.aliyuncs.com/centos-vault/RPM-GPG-KEY-CentOS-6
   
   [updates]
   name=CentOS-6.10
   enabled=1
   failovermethod=priority
   baseurl=http://mirrors.cloud.aliyuncs.com/centos-vault/6.10/updates/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.cloud.aliyuncs.com/centos-vault/RPM-GPG-KEY-CentOS-6
   
   [extras]
   name=CentOS-6.10
   enabled=1
   failovermethod=priority
   baseurl=http://mirrors.cloud.aliyuncs.com/centos-vault/6.10/extras/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.cloud.aliyuncs.com/centos-vault/RPM-GPG-KEY-CentOS-6

   After editing, press the Esc key, enter :wq, and press Enter to save and exit the file.

3. Switch the epel repository.

   sudo vim /etc/yum.repos.d/epel.repo

   To switch the repository, press i to enter edit mode and change the content as follows.

   [epel]
   name=Extra Packages for Enterprise Linux 6 - $basearch
   enabled=1
   failovermethod=priority
   baseurl=http://mirrors.cloud.aliyuncs.com/epel-archive/6/$basearch
   gpgcheck=0
   gpgkey=http://mirrors.cloud.aliyuncs.com/epel-archive/RPM-GPG-KEY-EPEL-6

   After editing, press the Esc key, enter :wq, and press Enter to save your changes and exit.

4. Run the yum repolist command. If the repository list is displayed successfully without a 404 error, the repository switch is successful.

How to switch the source configuration on a CentOS 6 instance?

When you use a custom image to create a new ECS instance, cloud-init automatically initializes the repository configuration of the system on startup. If you want to create a custom image from an instance that has a custom repository configuration and preserve that configuration, you must modify the cloud-init configuration file /etc/cloud/cloud.cfg on the source instance before you create the custom image.

1. Edit the /etc/cloud/cloud.cfg file.

   sudo vim /etc/cloud/cloud.cfg

2. Press i to enter edit mode and use # to comment out the - source-address module under cloud_init_modules:.

   After you comment out the module, the configuration in the file appears as follows:

3. After editing, press the Esc key, enter :wq, and press Enter to save and exit the file.