In this how-to article we will show you how to install Redis Sentinel using Ansible automation. But first, let’s start with a brief overview of Redis Sentinel and Ansible.
What is Redis?
Redis is an open-source, in-memory data structure store, used as a distributed, in-memory key–value database, cache and message broker, with optional durability. Redis supports different kinds of abstract data structures, such as strings, lists, maps, sets, sorted sets, HyperLogLogs, bitmaps, streams, and spatial indices.
Redis is often used as a database, cache, and message broker. It is also used for real-time data processing, analytics, and streaming. Redis is a popular choice for a variety of applications, including:
- Web applications
- E-commerce platforms
- Social media platforms
- Gaming platforms
- Real-time analytics
Redis is a fast, scalable, and reliable data store. It is also easy to use and has a large community of developers. If you are looking for a data store that can handle your needs, Redis is a great option.
What is Redis Sentinel?
Redis Sentinel is a distributed system that provides high availability for Redis. It does this by monitoring Redis instances and automatically taking over if a master instance fails. Sentinel also provides other features such as notification and automatic failover.
Some of the benefits of using Redis Sentinel:
- High availability: Redis Sentinel ensures that your Redis data is always available, even if a master instance fails.
- Automatic failover: If a master instance fails, Sentinel will automatically promote one of the slaves to be the new master.
- Notification: Sentinel can send notifications to you or other systems if a failure occurs.
- Configuration management: Sentinel can manage the configuration of your Redis instances, including the list of slaves for each master.
Redis Sentinel is a powerful tool that can help you ensure the high availability of your Redis data. If you are using Redis in a production environment, we highly recommend using Sentinel.
What is Ansible?
Ansible is an open-source IT automation platform that automates software provisioning, configuration management, application deployment, orchestration, and many other IT processes. Ansible is agentless, meaning that it does not require any software to be installed on the managed systems. Ansible uses a simple, declarative syntax that makes it easy to write automation scripts. Ansible is also highly scalable, making it suitable for use in large enterprise environments.
Here are some of the benefits of using Ansible:
- Simplicity: Ansible is easy to learn and use, even for users with no prior experience in IT automation.
- Scalability: Ansible is highly scalable, making it suitable for use in large enterprise environments.
- Security: Ansible is secure by design, and it can be used to automate even the most sensitive IT tasks.
- Reliability: Ansible is a reliable platform that has been used by thousands of organizations around the world.
- Community: Ansible has a large and active community of users and contributors, which provides support and resources for users of all levels of experience.
If you are looking for an IT automation platform that is simple, scalable, secure, reliable, and has a large and active community, then Ansible is a great option.
To follow this toturial, you will need the following:
- A server with Ubuntu 20.04 installed. You can install Ubuntu on a VPS, Dedicated Server or Bare Metal Server with GPU from the VelociHOST website.
- A sudo non-root user or direct root user access.
- The server’s firewall must allow SSH and HTTP(S) traffic.
- Ansible installed on your local machine.
- SSH Keys copied to target servers.
As a refresher, this is one ways to copy SSH keys to a target machine:
ssh-copy-idcommand is a simple and easy way to copy SSH keys to a target machine. To use the
ssh-copy-idcommand, you will need to know the username of the account on the target machine and the path to your SSH public key.
For example, to copy your SSH public key to the account with the username
myuser on the remote machine
myserver, you would use the following command:
You can check if you have any SSH keys by navigating to the
~/.ssh directory and listing the files with the following command:
If you have SSH keys, you should see files with the
.pub and no extension for the private key. If you don’t have any SSH keys, the directory will be empty.
Steps to install Redis Sentinel with Ansible on Debian or an Ubuntu server:
1. Install Ansible.
You can install Ansible using the following command:
sudo apt-get install ansible
2. Create an inventory file.
The inventory file is a text file that lists the hosts where you want to install Redis Sentinel. The following is an example of an inventory file:
[redis-sentinel] redis-sentinel1 redis-sentinel2 redis-sentinel3
3. Create a playbook.
The playbook is a YAML file that defines the tasks that you want Ansible to perform. The following is an example of a playbook that installs Redis Sentinel:
--- - hosts: redis-sentinel become: yes tasks: - name: Install Redis Sentinel apt: name: redis-sentinel state: present - name: Start Redis Sentinel service: name: redis-sentinel state: started enabled: yes
4. Run the playbook.
To run the playbook, you can use the following command:
ansible-playbook -i inventory.txt playbook.yml
This will install Redis Sentinel on the hosts listed in the inventory file.
5. Once Redis Sentinel is installed, you can use the following command to view the status of the sentinels:
redis-sentinel -h -p 26379
For example, to view the status of the sentinels on redis-sentinel1, you would use the following command:
redis-sentinel -h redis-sentinel1 -p 26379
This will output the following information:
# redis-sentinel 6.2.6 # Copyright (C) 2009-2022, Redis Inc. # Sentinel 1 # # 192.168.1.101:26379 # # ID = 6379 # CNAME = sentinel1 # SNAME = mymaster # ROLE = master # # 192.168.1.102:26379 # # ID = 6380 # CNAME = sentinel2 # SNAME = mymaster # ROLE = slave # # 192.168.1.103:26379 # # ID = 6381 # CNAME = sentinel3 # SNAME = mymaster # ROLE = slave
This shows that there are three sentinels, each of which is listening on a different port. The first sentinel is the master, and the other two sentinels are slaves.
In this article, we have shown you how to install Redis Sentinel using Ansible automation. We have covered the following steps:
- Install Ansible.
- Create a playbook.
- Create an inventory file.
- Run the playbook.
We hope this article has been helpful. If you have any questions on how to deploy this on a cloud server, please feel free to contact our support team at [email protected] .
Here are some additional tips for installing Redis Sentinel with Ansible:
- Use a version control system to track your Ansible playbooks and inventory files. This will make it easy to roll back changes if something goes wrong.
- Use Ansible roles to organize your Ansible playbooks. This will make your playbooks more modular and easier to maintain.
- Use Ansible tags to group your Ansible playbooks and inventory files. This will make it easy to run specific sets of playbooks or inventory files.
We hope these tips help you get the most out of Ansible.