# Customize web server


## Default Nginx configuration

The default Nginx static service has following configuration:

```
server {
    listen 80 default_server;
    listen [::]:80 default_server;

    server_name _;
    root {{.DocumentRoot}};

    location / {
        try_files $uri $uri/ /index.html;
    }

    access_log syslog:server=unix:/dev/log,facility=local1,tag=nginx,severity=info default_short;
    error_log syslog:server=unix:/dev/log,facility=local1,tag=nginx,severity=error;
}
```

The configuration contains 2 variables:

- **`{{.DocumentRoot}}`** is replaced by the [`run.documentRoot`](/nginx/how-to/build-pipeline#documentroot) attribute from the `zerops.yaml`. If the attribute is not specified, the default value `/var/www` is used.

## Customize Nginx configuration

Follow these steps to customize the Nginx configuration in Nginx static service:

1. Create a **.tmpl** file with the Nginx configuration in your repository.

2. Optionally use following variables:

- **`{{.DocumentRoot}}`** is replaced by the [`run.documentRoot`](/nginx/how-to/build-pipeline#documentroot) attribute from the `zerops.yaml`. If the attribute is not specified, the default value `/var/www` is used.

Example:

```
root {{.DocumentRoot}};
```

- **`{{.Environment.ENV_NAME}}`** is replaced by the [env variable](/nginx/how-to/env-variables) value. The env variable must be either defined in [run.envVariables](/nginx/how-to/build-pipeline#envvariables) in `zerops.yaml` or set as a [secret](/nginx/how-to/env-variables#set-secret-env-variables-in-zerops-gui) or [generated](/nginx/how-to/env-variables#generated-env-variables) env variable in Zerops GUI.

:::caution
Use the **.tmpl** file extension to make Zerops interpret the file as a template. Zerops will replace the supported variables listed above.
:::

3. Check that your Nginx configuration is consistent with Zerops requirements:

- Do not use IP addresses in the `listen` directive
- If you use other ports than `:80` in the `listen` directive, add them to the [`run.ports`](/nginx/how-to/build-pipeline#ports) in your `zerops.yaml` as well.
- Do not use the port **:443**. All the incoming `https://` traffic is terminated on the Zerops internal balancer where the SSL certificate is installed and the request is forwarded to your Nginx static service as a **http://** on the port **:80**.

4. Add the [`siteConfigPath`](/nginx/how-to/build-pipeline#siteconfigpath) to the run section of your `zerops.yaml`

```yaml
zerops:
  # define hostname of your service
  - setup: app
    # ==== how to build your application ====
    build:
      # REQUIRED. Set the base technology for the build environment:
      base: nodejs@latest

      # REQUIRED. Select which files / folders to deploy after
      # the build has successfully finished
      deployFiles:
        - vendor
        - public

    # ==== how to run your application ====
    run:
      documentRoot: public

      # OPTIONAL. Sets the custom Nginx or Apache configuration. The file must be deployed in the runtime container. Enter the path to the file relative to the /var/www folder
      siteConfigPath: site_config.tmpl
```

5. Ensure that the [`build.deployFiles`](/nginx/how-to/build-pipeline#deployfiles) contains the folder with the `siteConfigPath` or add the path to the Nginx config file to the `deployFiles` list. Zerops will deploy the file to the runtime container(s).

6. [Trigger](/nginx/how-to/trigger-pipeline) the build & deploy pipeline.

## SEO & Prerender Support

Single Page Applications and JavaScript-heavy sites render content client-side, which most crawlers can't process—they see an empty page instead of your content. This affects traditional search engines, social media platforms, and AI tools like ChatGPT, Perplexity, and Claude.

### Built-in Prerender.io Integration

The default Nginx configuration includes automatic [Prerender.io](https://prerender.io) support. When enabled, it detects crawler requests (including AI crawlers) and serves them pre-rendered HTML while your users get the full interactive experience.

### Setup

To enable prerender support:

1. Set the `PRERENDER_TOKEN` environment variable with your Prerender.io token (see [environment variables](/nginx/how-to/env-variables#prerenderio-support))
2. Optionally set `PRERENDER_HOST` if using a custom prerender server

The Nginx configuration will automatically handle the rest—no additional configuration needed.