# Dynamic watermarking with imgproxy and Apache APISIX

> Let's implement a watermarking feature with the help of imgproxy. The more I think about it, the more I think they make a match made in Heaven.

- URL: https://foojay.io/today/dynamic-watermarking-with-imgproxy-and-apache-apisix/
- Published: 2024-07-10
- Authors: Nicolas Frankel
- Categories: DevOps
- Originally published at: https://blog.frankel.ch/dynamic-watermarking/2/


I described [how to add a dynamic watermark to your images on the JVM](https://foojay.io/today/dynamic-watermarking-on-the-jvm/). I didn't find any library, so I had to develop the feature, or, more precisely, an embryo of a feature, by myself.

Depending on your tech stack, you must search for an existing library or roll up your sleeves. For example, Rust offers such an out-of-the-box library. Worse, this approach might be impossible to implement if you don't have access to the source image.

Another alternative is to use ready-made components, namely [imgproxy](https://imgproxy.net/) and [Apache APISIX](https://apisix.apache.org/). I already combined them to [resize images on-the-fly](https://blog.frankel.ch/resize-images-on-the-fly/).

Here's the general sequence flow of the process:

![](watermark_sequence_diagram.png)

* When APISIX receives a specific pattern, it calls `imgproxy` with the relevant parameters
* `imgproxy` fetches the original image and the watermark to apply
* It watermarks the original image and returns the result to APISIX

Let's say the pattern is `/watermark/*`.

We can define two routes:

```yaml
routes:
  - uri: "*"                                                                     #1
    upstream:
      nodes:
        "server:3000": 1
  - uri: /watermark/*                                                            #2
    plugins:
      proxy-rewrite:                                                             #3
        regex_uri:
          - /watermark/(.*)
          - /dummy_sig/watermark:0.8:nowe:20:20:0.2/plain/http://server:3000/$1  #4
    upstream:
      nodes:
        "imgproxy:8080": 1                                                       #5
```

1. Catch-all route that forwards to the web server
2. Watermark images route
3. Rewrite the URL...
4. ...with an `imgproxy`-configured route and...
5. ...forward to `imageproxy`

You can find the exact rewritten URL syntax in [imgproxy](https://docs.imgproxy.net/features/watermark) documentation. The watermark itself is configured via a single environment variable. You should buy `imgproxy`'s Pro version if you need different watermarks. As a poor man's alternative, you could also set up different instances, each with its watermark, and configure APISIX to route the request to the desired instance.

In this post, we implemented a watermarking feature with the help of `imgproxy`. The more I think about it, the more I think they make a match made in Heaven.

The complete source code for this post can be found on [GitHub](https://github.com/ajavageek/watermark-on-the-fly).

**To go further:**

* [Digital watermarking](https://en.wikipedia.org/wiki/Digital_watermarking)
* [imgproxy documentation](https://docs.imgproxy.net/)
* [imgproxy interactive demo](https://imgproxy.net/)

*Originally published at [A Java Geek](https://blog.frankel.ch/dynamic-watermarking/2/) on July 7th, 2024*