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[![Build Status](https://drone.asperti.com/api/badges/paspo/docker-mariadb-backup-slave/status.svg)](https://drone.asperti.com/paspo/docker-mariadb-backup-slave)
# docker-mariadb-backup-slave
Setup a mariadb slave server with automysqlbackup
[![Build Status](https://drone.asperti.com/api/badges/paspo/docker-mariadb-backup-slave/status.svg)](https://drone.asperti.com/paspo/docker-mariadb-backup-slave)
Setup a mariadb slave server with automysqlbackup
## Parameters
### SERVER_ID
This is used to customize slave server ID. The default value is 33. You should use an unique ID for each server.
### READONLY
When set to **1**, the slave server is set as readonly. This is the default. If you set this variable to something different, the database will be read/write.
### REPLICATE_DO_DB
This is used to specify a single database to backup. It is generally advised to set this variable to the database name you want to backup.
This is used to specify a single database to backup. It is generally advised to set this variable to the database name you want to backup.
## How to setup a mysql slave for backup
### Configure the master node
Examine all mariadb config files, they're usually located in **/etc/mysql/**. You must have these instructions:
```
```ini
[mysqld]
server_id = 1
log_bin
@ -41,7 +42,7 @@ After these modifications, restart mariadb.
Execute this statement on the master node:
```
```sql
grant replication slave on *.* to repluser@backupslave.host identified by 'aRandomPassword'; flush privileges;
```
@ -51,7 +52,7 @@ Replace **repluser**, **backupslave.host**, **aRandomPassword** with something m
We use docker-compose here, but you can do the same with plain docker. Here's a sample **docker-compose.yaml** file:
```
```yaml
version: "3"
services:
@ -69,12 +70,14 @@ services:
```
Start the container:
```
```bash
docker-compose up -d
```
Create the database:
```
```bash
docker exec my-container sh -c 'echo "create database aWordpressDatabase;" | exec mysql -uroot -p"$MYSQL_ROOT_PASSWORD"'
```
@ -82,7 +85,8 @@ docker exec my-container sh -c 'echo "create database aWordpressDatabase;" | exe
To obtain a consistant slave, you first have to freeze the master, and then transfer the data.
Execute this on the master:
```
```sql
FLUSH TABLES WITH READ LOCK;
show master status;
```
@ -92,6 +96,7 @@ show master status;
Take note of file and position, we'll need these informations later.
### Import initial data
We have two ways to copy the data from the master to the slave: we'll call these "live" and "classic".
The classic way is the usual mysqldump + file transfer + import.
The live way is dump + import at the same time, without an intermediate file.
@ -99,47 +104,62 @@ The live way is preferred when you have small databases (less than 5Gb) and a go
The classic way is preferred when you have a big database because it locks the database for less time.
### Import initial data (live version)
Now, we need to import the backup from the master, so as we started the slave as readwrite, we can now do this on the slave:
```
```bash
docker exec my-container sh -c 'mysqldump -C --lock-tables=false --quick -u repluser -h master.host --password="aRandomPassword" aWordpressDatabase | mysql -u root -p"$MYSQL_ROOT_PASSWORD" aWordpressDatabase'
```
Replace **my-container**, **repluser**, **master.host**, **aRandomPassword**, **aWordpressDatabase** with the correct values.
Replace **my-container**, **repluser**, **master.host**, **aRandomPassword**, **aWordpressDatabase** with the correct values.
Now that the slave has got some data, we can release the lock in the master:
```
```bash
UNLOCK TABLES;
```
### Import initial data (classic version)
In the master we run mysqldump in a shell:
```
```bash
mysqldump -u root -p aWordpressDatabase | gzip > thedump.sql.gz
```
When the export is finished, we can let the master resume his work, by issuing this command in the previous mysql session:
```
```bash
UNLOCK TABLES;
```
We can proceed to transfer the dump file to the slave; use the method you prefer.
On the slave, copy the dump file in the running container, like this:
```
```bash
docker cp thedump.sql.gz my-container:/thedump.sql.gz
```
Then we import it:
```
Then we import it:
```bash
docker exec my-container sh -c 'zcat /thedump.sql.gz | mysql -u root -p"$MYSQL_ROOT_PASSWORD" aWordpressDatabase'
docker exec my-container sh -c 'rm /thedump.sql.gz'
```
Replace **my-container**, **aWordpressDatabase** with the correct values.
### Start the slave
Replace **my-container**, **aWordpressDatabase** with the correct values.
### Start the slave
Open a mysql console in the slave:
```
```bash
docker exec -ti my-container sh -c 'mysql -u root -p"$MYSQL_ROOT_PASSWORD" aWordpressDatabase'
```
And configure the replication:
```
```sql
STOP SLAVE;
RESET SLAVE;
CHANGE MASTER TO
@ -153,12 +173,16 @@ CHANGE MASTER TO
MASTER_CONNECT_RETRY=10;
START SLAVE;
```
### Check replication status
```
```bash
docker exec -ti my-container sh -c 'mysql -u root -p"$MYSQL_ROOT_PASSWORD" aWordpressDatabase -e "SHOW SLAVE STATUS\G;"'
```
Example output:
```
```sql
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: master.host
@ -209,18 +233,23 @@ Master_SSL_Verify_Server_Cert: No
Parallel_Mode: conservative
1 row in set (0.00 sec)
```
In a normal condition, **Slave_IO_Running** and **Slave_SQL_Running** should be **Yes**: this means that the communication between master and slave is ok and no sync error has occourred. **Seconds_Behind_Master** is usually 0, except wen the communication has just been established and the slave has to catch up with the master. This situation usually resolves in some time.
### Make the slave read-only
For a safety measure, we're enabling read-only mode for the slave: we don't have to run any query on this host, we're just using it for scheduled backups.
Reopen **docker-compose.yaml**, change **READONLY=0** to **READONLY=1** and restart the container:
```
```bash
docker-compose up -d
```
## How to use different mariadb version
The default is mariadb 10.4.
If you want, you can use mariadb 10.3, 10.2 or 10.1 by changing this line in **docker-compose.yaml**:
```
The default is mariadb 10.5.
If you want, you can use mariadb 10.4, 10.3, or 10.2 by changing this line in **docker-compose.yaml**:
```yaml
image: docker.asperti.com/paspo/mariadb-backup-slave:maria-10.1
```
```