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How to Setup Smush to Serve WebP Images on Nginx

4 min read

This article will walk you through how to setup Smush to serve webp files on specific websites on your GridPane servers.

You can also checkout the official Smush documentation here:

https://wpmudev.com/blog/local-webp-support-smush/#NGINX

Step 1. SSH into your server

Please see the following articles to get started:

Step 2: Create webp-mappings.conf

We first need to create an Nginx configuration (aka config / .conf) file so that our server can serve WebP files. This first config makes use of the HTTP Context which applies server-wide.

HTTP Context includes the following:

http {
  include /etc/nginx/common/basics.conf;
  #include /etc/nginx/common/geoip.conf;
  include /etc/nginx/common/limits.conf;
  include /etc/nginx/mime.types;
  include /etc/nginx/common/ssl.conf;
  include /etc/nginx/common/logging.conf;
  include /etc/nginx/common/6g-mappings.conf;
  include /etc/nginx/conf.d/*.conf;
  include /etc/nginx/extra.d/http-context.conf;
  include /etc/nginx/sites-enabled/*;
}

We’ll make use of the include highlighted in red to create our new config, which ensures that any .conf file added to the /etc/nginx/conf.d/  directory applies server-wide.

This step will only need to be set up once per server. If you’re adding Smush to more than one site, you can skip this step for your 2nd site onwards.

So, to summarise, we’ll create a file called webp-mappings.conf in the /etc/nginx/conf.d/ directory.

Create webp-mappings.conf

Create the file with the following command:

nano /etc/nginx/conf.d/webp-mappings.conf

Paste the following block of code:

map $http_accept $webp_suffix {
default ""; 
"~*webp" ".webp"; 
}

Now Ctrl+O and then press Enter to save the file. Then Ctrl+X to exit nano.

Step 3: Create webp-main-context.conf

We now have 2 options for how to proceed. We can apply our WebP settings server-wide, or just on one specific site. You may find that it’s easier and more convenient to simply apply the changes server-wide if you’re using Smush on more than one website. We’ll look at both options below.

Option 1. Create a Server-Wide Configuration

The code supplied by Smush only works on individual sites. We’ve modified it so that you can set live for all your sites in one go and then just never need to worry about it.

To set this up, we need to create a file called smush-webp-main-context.conf in the /etc/nginx/extra.d/ directory.

Create the file with the following command:

nano /etc/nginx/extra.d/smush-webp-main-context.conf

Paste the following block of code:

location ~* "wp-content\/(uploads\/)(.*.(?:png|jpe?g))" {
add_header Vary Accept;
set $image_path $2;
if (-f "/var/www/$host/htdocs/wp-content/smush-webp/disable_smush_webp") {
break;
}
if ($http_accept !~* "webp") {
break;
}
try_files /wp-content/smush-webp/$image_path.webp $uri =404;
}

Now Ctrl+O and then press Enter to save the file. Then Ctrl+X to exit nano. You can now proceed to step 4.

Option 2. Create a Site-Specific Configuration

For a singular website, we need to create a file called smush-webp-main-context.conf  in /var/www/site.url/nginx.

Create the file with the following, switching out “site.url” with your website’s domain:

nano /var/www/site.url/nginx/smush-webp-main-context.conf

Paste the following block of code, again switching out “site.url” with your website’s domain:

# BEGIN SMUSH-WEBP
location ~* "wp-content\/(uploads\/)(.*.(?:png|jpe?g))" {
add_header Vary Accept;
set $image_path $2;
if (-f "/var/www/site.url/htdocs/wp-content/smush-webp/disable_smush_webp") {
break;
}
if ($http_accept !~* "webp") {
break;
}
try_files /wp-content/smush-webp/$image_path.webp $uri =404;
}
# END SMUSH-WEBP

Now Ctrl+O and then press enter to save the file. Then Ctrl+X to exit nano.

Staging Push Note

When pushing from live to staging or vice versa, the site.url in the site-specific config will need to be edited to the correct website (e.g. staging.site.url), otherwise the $root will be incorrect and WebP files will cease to work.

Step 4: Check and reload Nginx

Finally, we need to check if the conf files are correct then reload Nginx. 

Test your nginx syntax with:

nginx -t

If there are no errors present, reload nginx with the following command:

gp ngx reload

PHP Notice

If WebP images still aren't being served as you expected, please double check your PHP version. If you're still on 7.2 or 7.3, upgrading to 7.4 is both a good idea and may help resolve this issue for you.

Step 5: Check Your Work

Back inside your website in the Local WebP section of Smush, you can confirm your connection is set up. You’ll see the following:

After you’ve completed the set up you can recheck the status anytime on the same page:

Check WebP’s are Being Served

Verifying that images are being served as webp with Smush is detailed here in their docs:

Smush: Verifying WebP Output Documentation

It’s a little different to most other plugins where you can verify the HTML output. Instead, you can check the image in the network tab like so: