HA Provisioning For Backend Instances For Maxwell




In my previous post I have explain how we are running maxwell as service in Ubuntu. Now in this post I will be explaining how we achieved HA for Backend Instances (MySQL Hosts), Maxwell was using to read binlog.

So the stack we have introduced to achieve high availability contains HAProxy (http://www.haproxy.org/) and GTID enabled slaves. HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

We have installed HAProxy on the local machine where we are running Maxwell and configured maxwell to connect to localhost where we have used HAProxy primary-secondary backup strategy using below config (/etc/haproxy/haproxy.cfg):

defaults
       mode tcp
       timeout connect 5000ms
       timeout client 86400s
       timeout server 86400s

listen  MySQL
        bind 127.0.0.1:3306
        mode tcp
        option mysql-check user haproxy  # mysql-check enables a database server check, to determine whether the node is currently operational
server Primary host1:3306 check
server Secondary host2:3306 check backup

Now stack becomes:


This stack has solved our problem incase MySQL slave goes down, Our whole pipeline will not be impacted.

Next Post: We will be publishing on How we achieved HA for Maxwell service. 

Comments

  1. PalashFebruary 13, 2019 at 8:33 PM

    can you please elaborate why were GTID slaves needed in the first place?

    ReplyDelete
  2. Ankit KumarFebruary 14, 2019 at 11:08 AM

    Hey Thanks for going through the blog. Maxwell read binlogs using either coordinates (binlog name and position) or GTID. So there might be data mismatch or coordinate not found issue if we do not use GTID enabled slaves and do switchover to secondary slave.

    ReplyDelete

Post a Comment

Popular posts from this blog

Shell/Bash Commands Execution from MySQL Client or Stored Procedure/function

Image
Today I am going to explain ways to execute shell or bash commands from mysql clients or stored procedure and function. There are basically 2 method to do so: Method 1: Use MySQL Client inbuilt feature  To run single command: \! command or system command. eg \! uptime or system command  To get terminal \! bash or \! sh Method 2: Deploy external plugin ( lib_mysqludf_sys ) Step 1: Download lib_mysqludf_sys from github: git clone https://github.com/mysqludf/lib_mysqludf_sys.git Step 2: Install libmysqlclient15-dev, for Ubuntu you can use: apt-get install libmysqlclient15-dev Step 3: Note down o/p of: mysql -uroot -pxxxx -e "select @@plugin_dir;" Step 4: Change directory to git clone dir. cd lib_mysqludf_sys/ Step 5: Compile and put plugin in plugin dir gcc -Wall -I/usr/include/mysql -I. -shared lib_mysqludf_sys.c -o {value from step 3}lib_mysqludf_sys.so -fPIC Step 6: Create necessary functions for lib_mysqludf_sys: mysql -uroo...
Read more

Azure VM Application Consistent MySQL DB Disk Snapshots

Image
Backup of Database is the pillar of our system which is necessary and mandatory to provide us data incase of crash, new machine provisioning and many other scenarios listed here .  As part of the backup process, a snapshot is taken, and the data is transferred to the Recovery Services vault with no impact on production workloads. The snapshot provides different levels of consistency, as described below: 1. Application-consistent: App-consistent backups capture memory content and pending I/O operations. App-consistent snapshots use a VSS writer (or pre/post scripts for Linux) to ensure the consistency of the app data before a backup occurs. When you're recovering a VM with an app-consistent snapshot, the VM boots up. There's no data corruption or loss. The apps start in a consistent state. 2. File-system consistent: File-system consistent backups provide consistency by taking a snapshot of all files at the same time. When you're recovering a VM with a file-system cons...
Read more

How to remove/deregister an instance from PMM?

Image
We all need a monitoring system like pmm to monitor our database. Let me give a brief about how pmm works. So PMM uses prometheus to store metrics/graphs and grafana to display them. As seen in the architecture diagram prometheus uses consul to get the list of host to scrap metrics. More information on architecture and installation are available in docs. We were facing issues related to down hosts and if setup alerts in grafana for down host and host is terminated it continuously throws alerts. So problem was how can we remove/deregister instances from pmm. We can access consul UI using below link: http://PMM-SERVER/consul/#/dc1/ Previously there was option available on this ui to deregister host. while in the new releases of consul it has been removed see link . But now we can use below procedure from command line to deregister hosts from consul. Get list of nodes: curl -s 'http://USER:PASSWORD@PMM-SERVER-IP/v1/internal/ui/nodes?dc=dc1' | python -mjso...
Read more