Install Redis and Combine With Varnish and Nginx for M2 On Ubuntu 16.04

Ref: https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04
https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-18-04

Install Redis Server

Then modify /etc/redis/redis.conf file. In the file, find the supervised directive. Currently, this is set to no. Since we are running an operating system that uses the systemd init system, we can change this to systemd:

Next, find the dir directory. This option specifies the directory that Redis will use to dump persistent data. We need to pick a location that Redis will have write permission and that isn’t viewable by normal users.

We will use the /var/lib/redis directory for this, which we will create in a moment:

Save and close the file when you are finished.

Create a Redis systemd Unit File
Next, we can create a systemd unit file so that the init system can manage the Redis process.

Create and open the /etc/systemd/system/redis.service file to get started:

Inside, we can begin the [Unit] section by adding a description and defining a requirement that networking be available before starting this service. In the [Service] section, we need to specify the service’s behavior. For security purposes, we should not run our service as root. We should use a dedicated user and group, which we will call redis for simplicity. We will create these momentarily.

To start the service, we just need to call the redis-server binary, pointed at our configuration. To stop it, we can use the Redis shutdown command, which can be executed with the redis-cli binary. Also, since we want Redis to recover from failures when possible, we will set the Restart directive to “always”. Finally, in the [Install] section, we can define the systemd target that the service should attach to if enabled (configured to start at boot):
<DONT USE THIS SETTING>

</DONT USE THIS SETTING>

<USE THIS SETTING>

</USE THIS SETTING>
Save and close the file when you are finished. After saving and closing the file, I reloaded the systemd manager configuration:

Create the Redis User, Group and Directories
Now, we just have to create the user, group, and directory that we referenced in the previous two files.

Begin by creating the redis user and group. This can be done in a single command by typing:

Now, we can create the /var/lib/redis directory by typing:

We should give the redis user and group ownership over this directory:

Adjust the permissions so that regular users cannot access this location:

Start and Test Redis
Now, we are ready to start the Redis server.

Start the Redis Service

Check that the service had no errors by running:

I got the below error previously because the wrong setting in the redis.service file.

Check it on the terminal

Or make sure port 6379 only be using by redis

Test the Redis Instance Functionality
To test that your service is functioning correctly, connect to the Redis server with the command-line client:

Check that you can set keys by typing:

Enable Redis to Start at Boot
If all of your tests worked, and you would like to start Redis automatically when your server boots, you can enable the systemd service.

To do so, type:

Go to your magento root directory and open app/etc/env.php and add the below codes just before the last line.

Restart the Redis server

Check whether Redis server is working or not. Open your website and view some pages then  run the command

If you see this  keyspace. Then your Redis is configured properly. If you do not see anything below Keyspace then Redis have not cached anything. In this case check your configuration

To flush the Redis cache run the following command

Now your site is optimized with Varnish and Redis.

Benchmark
When I open https://fontaineind.test/ for the first time (varnish after fresh restart still caching so the page load still slower and redis also after first restart and flushdb command executed). I got this from redis-cli info:

Then I refresh the same page (varnish cache is kicking off and redis as well). I noticed the page load faster than only from varnish. But not much. Probably from 10-12 seconds to 8-9 seconds. Here is the output from redis-cli info:

I need to analyze these later.