Ubuntu

sudo apt-get update -yqq
sudo apt-get install -yqq p7zip-full

Fedora or CentOS / RHEL

CentOS 7.x Download and install manually

wget https://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/epel/7/x86_64/Packages/p/p7zip-16.02-10.el7.x86_64.rpm
wget https://www.mirrorservice.org/s...

Add a Node to Percona XtraDB Cluster on RHEL 9

Prerequisites

• Cluster bootstrapped and running
• PXC installed on this node
• Ports 3306, 4444, 4567, 4568 open

Configure this node (/etc/my.cnf, example Node 2)

[mysqld]
server-id            = 2
wsrep_on             = ON
wsrep_provider...

Apache .htaccess and mod_rewrite on RHEL 9

Enable mod_rewrite

# mod_rewrite is loaded by default in /etc/httpd/conf.modules.d/00-base.conf

Allow overrides in virtual host

    AllowOverride All
    Require all granted

Common .htaccess recip

Apache + PHP-FPM on RHEL 9

Step 1 – Enable proxy modules

dnf install -y php php-fpm
systemctl enable --now php-fpm

Step 2 – Virtual host with PHP-FPM handler

    ServerName example.com
    DocumentRoot /var/www/example.com/html
    
        SetHandler "p...

Bootstrap a Percona XtraDB Cluster on RHEL 9

Nodes: 192.168.1.10 (bootstrap) · 192.168.1.11 · 192.168.1.12

Step 1 – Configure Node 1 (/etc/my.cnf)

[mysqld]
server-id            = 1
wsrep_on             = ON
wsrep_provider       = /usr/lib64/galera4/libgalera_smm.so
wsrep_cluster_name...

Configure Apache Virtual Hosts on RHEL 9

Step 1 – Create document root

mkdir -p /var/www/example.com/html
echo '
Works!
' > /var/www/example.com/html/index.html
chown -R www-data:www-data /var/www/example.com 2>/dev/null || chown -R apache:apache /var/www/example.com 2>/dev/null || true

Configure firewalld on RHEL 9

Status

systemctl status firewalld
firewall-cmd --state
firewall-cmd --list-all

Allow common services

firewall-cmd --permanent --add-service=http
firewall-cmd --permanent --add-service=https
firewall-cmd --permanent --add-service=ssh
firewall-cmd --permanent --ad...

Configure Nginx as a Reverse Proxy on RHEL 9

Basic reverse proxy

upstream backend {
    server 127.0.0.1:3000;
}

server {
    listen 80;
    server_name app.example.com;
    location / {
        proxy_pass         http://backend;
        proxy_http_version 1.1;
        proxy_set_header   Upgrad...

Configure Nginx Virtual Hosts on RHEL 9

Step 1 – Create the document root

mkdir -p /var/www/example.com/html
echo '
Works!
' > /var/www/example.com/html/index.html

Step 2 – Create /etc/nginx/conf.d/example.com.conf

server {
    listen 80;
    listen [::]:80;
    server_name example.c...

Configure OpenSMTPD on RHEL 9

Install

# OpenBSD – built-in:
rcctl enable smtpd && rcctl start smtpd

# Other platforms:
# Ubuntu/Debian:
apt install opensmtpd
# AlmaLinux/RHEL:
dnf install opensmtpd
# Arch:
pacman -S opensmtpd

Basic /etc/mail/smtpd.conf

pki mail.example.com cert "/etc/ssl/m...

Elasticsearch Multi-Node Cluster on RHEL 9

Nodes: node-1 192.168.1.10 · node-2 192.168.1.11 · node-3 192.168.1.12

Node 1 elasticsearch.yml

cluster.name: production-cluster
node.name: node-1
node.roles: [master, data, ingest]
network.host: 192.168.1.10
http.port: 9200
transport.port: 930...

Elasticsearch Snapshot Backup on RHEL 9

Register filesystem repository

mkdir -p /var/backups/elasticsearch
chown elasticsearch:elasticsearch /var/backups/elasticsearch

elasticsearch.yml: path.repo: ["/var/backups/elasticsearch"]

curl -X PUT "https://localhost:9200/_snapshot/my_backup" \...

Enable TLS/SSL on Apache – RHEL 9

Step 1 – Enable mod_ssl

dnf install -y mod_ssl && systemctl restart httpd

Step 2 – Generate self-signed certificate

openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
    -keyout /etc/ssl/private/apache-selfsigned.key \
    -out /etc/ssl/certs/apache-self...

Enable TLS/SSL on Nginx – RHEL 9

Step 1 – Self-signed certificate (testing)

openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
    -keyout /etc/ssl/private/nginx-selfsigned.key \
    -out /etc/ssl/certs/nginx-selfsigned.crt \
    -subj "/CN=example.com"
openssl dhparam -out /etc/ssl/certs/dhp...

HAProxy MySQL Load Balancing on RHEL 9

Config section

listen mysql-cluster
    bind *:3306
    mode    tcp
    option  mysql-check user haproxy_check
    balance leastconn
    server db1 192.168.1.10:3306 check weight 1
    server db2 192.168.1.11:3306 check weight 1
    server db3 192.168.1.12:...

HAProxy TLS Termination on RHEL 9

Step 1 – Combine cert + key

cat /etc/ssl/certs/example.com.crt /etc/ssl/private/example.com.key > /etc/haproxy/certs/example.com.pem
chmod 600 /etc/haproxy/certs/example.com.pem
openssl dhparam -out /etc/haproxy/dhparam.pem 2048

Step 2 – Config

global
    ss...

Harden SSH on RHEL 9

Back up config

cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

Key settings (/etc/ssh/sshd_config)

Port 2222
PermitRootLogin no
PasswordAuthentication no
PubkeyAuthentication yes
AllowUsers deploy alice
Protocol 2
ClientAliveInterval 600
ClientAliveCountMax 0
X11Forwa...

Install and Configure Postfix on RHEL 9

Step 1 – Install

dnf install -y postfix mailx
systemctl enable --now postfix

Step 2 – /etc/postfix/main.cf

myhostname  = mail.example.com
mydomain    = example.com
myorigin    = $mydomain
inet_interfaces = all
inet_protocols = all
mydestination = $myh...

Install Apache HTTP Server on RHEL 9

Step 1 – Install

subscription-manager repos --enable codeready-builder-for-rhel-9-$(arch)-rpms
dnf install -y httpd mod_ssl
systemctl enable --now httpd

Step 2 – Open firewall ports

firewall-cmd --permanent --add-service=http
firewall-cmd --permanent --ad...

Install Docker on RHEL 9

Step 1 – Install

dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
dnf install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
systemctl enable --now docker

Step 2 – Add user to docker group

usermod -aG docker $USER...

Install Elasticsearch on RHEL 9

Step 1 – Install

rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch
cat > /etc/yum.repos.d/elasticsearch.repo <