Documentation update

docs/replication.md

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+# Namingo Registry Database Replication
+
+## MariaDB
+
+1. Configuration of MariaDB Galera Cluster
+
+To begin, you need to configure each node (database server) in your MariaDB Galera cluster. This involves editing the configuration file located at ```/etc/mysql/mariadb.conf.d/60-galera.cnf``` on each server. Below are the steps for each node:
+
+**Master Database Server:**
+
+Access the configuration file: Open ```/etc/mysql/mariadb.conf.d/60-galera.cnf``` for editing.
+
+Apply Configuration: Replace the existing content with the provided settings:
+
+```bash
+[mysqld]
+binlog_format=ROW
+default-storage-engine=innodb
+innodb_autoinc_lock_mode=2
+bind-address=0.0.0.0
+
+# Galera Provider Configuration
+wsrep_on=ON
+wsrep_provider=/usr/lib/galera/libgalera_smm.so
+
+# Galera Cluster Configuration
+wsrep_cluster_name="galera_cluster"
+wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"
+
+# Galera Synchronization Configuration
+wsrep_sst_method=rsync
+
+# Galera Node Configuration
+wsrep_node_address="node1-ip-address"
+wsrep_node_name="node1"
+```
+
+**Second Database Server:**
+
+Configuration File Editing: Similar to the master server, edit ```/etc/mysql/mariadb.conf.d/60-galera.cnf```.
+
+Update Settings: Replace the existing content with:
+
+```bash
+[mysqld]
+binlog_format=ROW
+default-storage-engine=innodb
+innodb_autoinc_lock_mode=2
+bind-address=0.0.0.0
+
+# Galera Provider Configuration
+wsrep_on=ON
+wsrep_provider=/usr/lib/galera/libgalera_smm.so
+
+# Galera Cluster Configuration
+wsrep_cluster_name="galera_cluster"
+wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"
+
+# Galera Synchronization Configuration
+wsrep_sst_method=rsync
+
+# Galera Node Configuration
+wsrep_node_address="node2-ip-address"
+wsrep_node_name="node2"
+```
+
+**Third Database Server:**
+
+Edit Configuration: Again, modify ```/etc/mysql/mariadb.conf.d/60-galera.cnf``` as done for the other servers.
+
+Implement Changes: Replace the configuration settings with:
+
+```bash
+[mysqld]
+binlog_format=ROW
+default-storage-engine=innodb
+innodb_autoinc_lock_mode=2
+bind-address=0.0.0.0
+
+# Galera Provider Configuration
+wsrep_on=ON
+wsrep_provider=/usr/lib/galera/libgalera_smm.so
+
+# Galera Cluster Configuration
+wsrep_cluster_name="galera_cluster"
+wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"
+
+# Galera Synchronization Configuration
+wsrep_sst_method=rsync
+
+# Galera Node Configuration
+wsrep_node_address="node3-ip-address"
+wsrep_node_name="node3"
+```
+
+2. Stopping MariaDB Services
+
+For all three database servers, you need to halt the MariaDB service. This can be done using the following command:
+
+```bash
+systemctl stop mariadb
+```
+
+3. Initializing the Galera Cluster
+
+Only on the master database server, you will initiate the cluster:
+
+Start the Cluster: Execute ```galera_new_cluster``` to initialize.
+
+Verify Cluster Status: Check the cluster's status with the command:
+
+```bash
+mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_cluster_size'"
+```
+
+This should return a cluster size of 1.
+
+4. Starting and Verifying Other Nodes
+
+For the remaining nodes, perform the following:
+
+**Second Node:**
+
+Start MariaDB: Use ```systemctl start mariadb```.
+
+Confirm Cluster Status: Execute the same status command as on the master. The cluster size should now be 2.
+
+**Third Node:**
+
+Service Initiation: Again, start MariaDB with ```systemctl start mariadb```.
+
+Status Check: Verify the cluster status. The expected cluster size should be 3.
+
+By following these steps, you will have successfully updated the replication settings for your MariaDB Galera Cluster in Namingo.
+
+## MySQL
+
+Overview
+
+This document outlines the process for setting up a basic master-slave replication in MySQL. Replication enables data from one MySQL database server (the master) to be replicated to one or more MySQL database servers (the slaves).
+
+Prerequisites
+
+- Two or more MySQL servers (version 5.7 or later recommended).
+
+- Network connectivity between the master and slave servers.
+
+- Identical MySQL version on all servers.
+
+- Unique server IDs for each server in the my.cnf or my.ini file.
+
+1. Configure the Master Server
+
+On the master server, edit the MySQL configuration file (typically ```my.cnf``` or ```my.ini```):
+
+```bash
+[mysqld]
+server-id=1
+log_bin=mysql-bin
+binlog_do_db=registry
+binlog_do_db=registryTransactions
+binlog_do_db=registryAudit
+```
+
+- ```server-id```: Unique identifier for the master server.
+
+Restart MySQL to apply these changes.
+
+2. Create a Replication User on the Master
+
+Log in to the MySQL master server and create a dedicated user for replication:
+
+```bash
+CREATE USER 'replicator'@'%' IDENTIFIED BY 'password';
+GRANT REPLICATION SLAVE ON *.* TO 'replicator'@'%';
+```
+
+Replace ```'password'``` with a secure password.
+
+3. Obtain Master Status Information
+
+Execute the following command on the master:
+
+```bash
+SHOW MASTER STATUS;
+```
+
+Note down the File and Position values, as these will be needed when configuring the slave server.
+
+4. Configure the Slave Server
+
+On the slave server, edit the MySQL configuration:
+
+```bash
+[mysqld]
+server-id=2
+relay_log=relay-log
+```
+
+- ```server-id```: Unique identifier for the slave server.
+
+Restart MySQL on the slave server.
+
+5. Set up the Slave to Replicate the Master
+
+On the slave server, run the following command:
+
+```bash
+CHANGE MASTER TO
+MASTER_HOST='master_ip_address',
+MASTER_USER='replicator',
+MASTER_PASSWORD='password',
+MASTER_LOG_FILE='recorded_log_file_name',
+MASTER_LOG_POS=recorded_log_position;
+```
+
+Replace ```'master_ip_address'```, ```'recorded_log_file_name'```, and ```'recorded_log_position'``` with the actual master server IP address, and the file and position values noted earlier.
+
+6. Start the Slave
+
+Finally, start the replication on the slave:
+
+```bash
+START SLAVE;
+```
+
+7. Verify Replication
+
+Check the slave status:
+
+```bash
+SHOW SLAVE STATUS\G
+```
+
+Look for ```Slave_IO_Running``` and ```Slave_SQL_Running``` both being set to Yes.
+
+## PostgreSQL
+
+1. Configure the Primary Server
+
+On the primary server, edit the PostgreSQL configuration file (```postgresql.conf```):
+
+```bash
+# Enable WAL (Write-Ahead Logging) archiving
+wal_level = replica
+archive_mode = on
+archive_command = 'cp %p /path_to_wal_archive/%f'
+
+# Set the maximum number of WAL senders
+max_wal_senders = 3
+
+# Set the connection timeout for replication connections
+wal_sender_timeout = 60s
+```
+
+- ```wal_level```: Set to replica to enable enough information for the standby server.
+
+- ```archive_mode``` and ```archive_command```: Configures archiving of WAL files.
+
+- ```max_wal_senders```: The maximum number of concurrent replication connections.
+
+- ```wal_sender_timeout```: The timeout for replication connections.
+
+2. Allow Replication Connections
+
+In ```pg_hba.conf```, add a line to allow connections from the standby server:
+
+```bash
+host replication replicator standby_ip_address/32 md5
+```
+
+Replace ```standby_ip_address``` with the actual IP address of the standby server.
+
+replicator is the replication user.
+
+3. Create a Replication User
+
+On the primary server, create a user for replication:
+
+```bash
+CREATE ROLE replicator REPLICATION LOGIN PASSWORD 'password';
+```
+
+4. Initialize the Standby Server
+
+Stop the PostgreSQL service on the standby server.
+
+Use ```pg_basebackup``` to make a base backup of the primary server:
+
+```bash
+pg_basebackup -h primary_ip_address -D /var/lib/postgresql/10/main -U replicator -P --wal-method=fetch
+```
+
+5. Configure the Standby Server
+
+On the standby server, create a recovery configuration file (```recovery.conf```):
+
+```bash
+standby_mode = 'on'
+primary_conninfo = 'host=primary_ip_address port=5432 user=replicator password=password'
+```
+
+6. Start the Standby Server
+
+Start PostgreSQL on the standby server. It will now start replicating from the primary server.
+
+7. Verify Replication
+
+Check the replication status on the primary server:
+
+```bash
+SELECT * FROM pg_stat_replication;
+```