# Customize error pages in your own Caddy Docker image
> [!IMPORTANT]
> Here we use an image with the `-builder` suffix. It's intended for generating error pages and already includes
> pre-rendered templates.
To set this up, we need two things:
- A Caddyfile configuration
- A Dockerfile to build the image
Let's start with the Caddyfile:
```caddy
# File: Caddyfile
:80 {
root * /usr/share/caddy
file_server
handle_errors {
root * /usr/share/errorpages
rewrite * /{err.status_code}.html
file_server
}
}
```
`handle_errors` is triggered whenever Caddy itself returns an error status (for example, a 404 from `file_server` or
a 502 from `reverse_proxy`). The `{err.status_code}` placeholder is replaced with the actual status code, so Caddy
will look for `/404.html`, `/502.html`, and so on in the error pages directory.
Now the Dockerfile:
```dockerfile
FROM docker.io/library/caddy:2.11-alpine
# override the default Caddy configuration
COPY --chown=root ./Caddyfile /etc/caddy/Caddyfile
# copy statically built error pages from the error-pages "builder" image
# (you can use a different template instead of `ghost` if you want)
COPY --chown=root \
--from=ghcr.io/tarampampam/error-pages:4-builder \
/opt/html/ghost /usr/share/errorpages
```
Next, build and run the image:
```shell
docker build --tag your-caddy:local -f ./Dockerfile .
docker run --rm -p '8081:80/tcp' your-caddy:local
```
And voilà! Let's verify that everything works as expected:
```shell
curl -s http://127.0.0.1:8081/foobar | head -n 15 # run this in another terminal
404: Not Found