CentOS upgrade, install, and RPMs

-

 CentOS 7 to CentOS 8 Upgrade Guide

Exalting CentOS 7 to CentOS 8 **in-place** is not supported officially due to distinctions between the two versions. CentOS 8 uses `dnf` (instead of `yum`) and comes with various changes to its libraries and structure. However, if you need to upgrade, follow these general steps to perform a fresh installation while maintaining backups:


1. Back Up Important Data: Always back up important data, configuration files, and databases.

   - Use tools like `rsync` or create a snapshot if you're on a virtual machine.


2. Install CentOS 8 Fresh: Download CentOS 8 ISO from the official site and perform a fresh installation.

 - Download link: [https://www.centos.org/download/](https://www.centos.org/download/)


3. Reconfigure and Restore Backups:

   - After installation, reinstall the necessary packages and restore your data from backup.

While there are scripts like `Leapp`, they are experimental and not recommended for production systems.


Upgrading from CentOS 7 to CentOS 8 involves several steps to ensure a smooth transition. Below is a structured guide to perform the Upgrade effectively.


## Step-by-Step Upgrade Guide


### 1. Backup Your Data

Before initiating the Upgrade, it's essential to back up your important data. Use tools like `rsync` or `tar` to create backups of your files and directories:

```bash

sudo rsync -av /path/to/your/data /path/to/backup/location

```

or

```bash

sudo tar czvf /path/to/backup/location/backup.tar.gz /path/to/your/data

```

### 2. Update CentOS 7

Ensure your current CentOS 7 system is fully updated:

```bash

sudo yum update -y

sudo yum upgrade -y

```


### 3. Clean Up Your System

Remove any unnecessary packages and orphaned dependencies:

```bash

sudo yum install -y yum-utils rpmconf

sudo rpmconf -a

package-cleanup --leaves

package-cleanup --orphans

```


### 4. Install Required Repositories

Install the Extra Packages for Enterprise Linux (EPEL) repository if it's not already installed:

```bash

sudo yum install -y epel-release

```


### 5. Install the DNF Package Manager

CentOS 8 uses DNF instead of YUM for package management. Install DNF and remove YUM:

```bash

sudo yum install -y dnf

sudo dnf -y remove yum yum-metadata-parser

rm -Rf /etc/yum

```

### 6. Upgrade to CentOS 8

Now, you can proceed to install the CentOS 8 release package and Upgrade:

```bash

sudo dnf install http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/{centos-release-8.x.rpm,centos-gpg-keys-8.x.noarch.rpm}

sudo dnf -y upgrade https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

```

Next, perform the final upgrade step:

```bash

sudo dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync

```

### 7. Install the New Kernel

After upgrading, install the new kernel core:

```bash

sudo dnf -y install kernel-core

```

### 8. Reboot Your System

Once the upgrade process is complete, reboot your system to apply changes:

```bash

sudo reboot

```

### 9. Verify the Upgrade

After rebooting, check if the Upgrade was successful by running:

```bash

cat /etc/centos-release

```

If it displays "CentOS Linux release 8.x", you have successfully upgraded.



How to Install MySQL on CentOS 7


To install MySQL on CentOS 7, follow these steps:

1. Add MySQL Yum Repository:

   ```bash

   sudo yum localinstall https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

   ```

2. Install MySQL:

   ```bash

   sudo yum install mysql-server

   ```

3. Start MySQL Service:

   ```bash

   sudo systemctl start mysqld

   sudo systemctl enable mysqld

   ```

4. Secure MySQL Installation:

   Run the security script to set the root password and secure the installation:

   ```bash

   sudo mysql_secure_installation

   ```

5. Login to MySQL:

   ```bash

   MySQL -u root -p

   ```

To install MySQL on CentOS 7, follow these detailed steps:


## Prerequisites

- A CentOS 7 system (either a VPS or dedicated server).

- A non-root user with **sudo** privileges.

- Access to the command line interface.


## Steps for Installation


Step 1: Update the System


Revise the package index on your system before starting the installation. Launch your terminal and type.

```bash

sudo yum update

```

### Step 2: Install wget (if not already installed)


If **wget** is not available on your system, install it using:

```bash

sudo yum install wget

```

### Step 3: Get the MySQL Repository Package here.


Need to download the MySQL Yum storage package. Use the following command to download the latest version (replace the version number if necessary):

```bash

wget https://dev.mysql.com/get/mysql80-community-release-el7-7.noarch.rpm

```

### Step 4: Install the MySQL Repository


Once downloaded, install the repository package with:

```bash

sudo rpm -ivh mysql80-community-release-el7-7.noarch.rpm

```

### Step 5: Install MySQL Server


Now that the repository is set up install MySQL Server by running:

```bash

sudo yum install mysql-server

```

### Step 6: Start and Enable MySQL Service


After installation, start the MySQL service and enable it to start on boot:

```bash

sudo systemctl start mysqld

sudo systemctl enable mysqld

```

### Step 7: Check MySQL Service Status


To verify that MySQL is running, check its status with:

```bash

sudo systemctl status mysqld

```

### Step 8: Secure MySQL Installation


A protection script contained with MySQL helps to ensure your installation. Use it with

```bash

sudo mysql_secure_installation

```

Follow the prompts to set up protection options, such as a root password, removing anonymous users, and disallowing remote root login.


## Conclusion


After completing these steps, you will have a fully functional MySQL installation on your CentOS 7 server. You can now log in to MySQL using:

```bash

MySQL -u root -p

```

This expertness will encourage you for the source password you set during the secure installation process.


Will CentOS RPM Work on Red Hat?


Yes, CentOS RPM packages generally work on Red Hat Enterprise Linux (RHEL) because CentOS is a downstream rebuild of RHEL. Both methods use the same package management means (`yum,` `dnf`), and CentOS packages are consistent with RHEL of the same major version.


However, for certain packages (especially proprietary software or custom builds), there could be slight differences that may require RHEL-specific versions or licenses.


Will Fedora RPM Work on CentOS?


Fedora RPMs strength works on CentOS, but there are possible issues:


Different Dependencies: Fedora is a more cutting-edge distribution, and packages in Fedora might rely on newer versions of libraries that aren't available in CentOS.


Stability: Fedora concentrates on newer software, while CentOS is more traditional and durable, with longer-term assets. Using Fedora RPMs on CentOS may lead to instability or compatibility issues.

It is recommended to use EPEL (Extra Packages for Enterprise Linux) for newer packages in CentOS, as they are designed for compatibility with RHEL/CentOS systems.


Yes, Red Hat Enterprise Linux (RHEL) can generally run CentOS RPM packages. The RPM packages built for CentOS are usually compatible with RHEL systems because CentOS is planned to be a binary-compatible clone of RHEL. Because both allocations use the RPM Package Manager for package control, users can inaugurate CentOS RPMs on RHEL without encountering any major issues.

However, there are some important considerations:


Support Limitations: Although CentOS RPMs can be established on RHEL, RedHat does not endorse third-party packages, including CentOS packages. If you run into issues with these packages, Red Hat help might not be able to assist you.


Potential Risks: Installing non-RHEL containers might lead to system instability or disputes with RHEL's supported packages. It's advisable to ensure that any extra software does not hinder the core system functionality.


Migration Tools: RedHat equips a tool dubbed Convert2RHEL for users who want to switch from CentOS to RHEL while maintaining their current apps and settings. This device enables a better seamless migration strategy by transforming a CentOS structure into a fully funded RHEL system.

In overview, while CentOS RPMs can work on RHEL due to their compatibility, users should be cautious about potential support issues and system stability.


:References


https://www.tecmint.com/upgrade-centos-7-to-centos-8/embed/

https://markaicode.com/how-to-install-and-configure-mysql-on-centos-8/

https://myrestraining.com/blog/aws/how-to-install-mysql-on-aws-ec2-linux/

https://markaicode.com/how-to-install-and-configure-mysql-on-centos-8/

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