feat(docker): specify a PUBLIC_URL/BASE_URL env var at runtime

[antoineauger]

Hello team,

We are currently checking what is "missing" to swagger-editor v5 (compared to v4) for our Kubernetes-based deployment.

We noticed that it was not possible to set a BASE_URL (like we used to have with #2281 for instance) at runtime through an environment variable. This was very useful for us.

Would you be open to the idea of adding this feature? This would be quite consistent with swagger-ui, see here.

We are aware of React limitations and the fact that swagger-editor v5 is also now packaged in an unprivileged fashion (so maybe this would be something only possible for privileged images).

I investigated some directions but React/WebPack/Monaco in Docker is not really a familiar setup for me. For instance, I thought about building the Docker image with a multi-stage build and by doing RUN PUBLIC_URL=__PUBLIC_URL_PLACEHOLDER__ npm run build:app but I'm not sure that it is then feasible to sed these placeholders at runtime.

Note: this issue is basically the same than #1956 but for v5

[antoineauger]

I just came across this note in the README:

No custom environment variables are currently supported by SwaggerEditor.

As a workaround, we will build our own Docker image from source by setting PUBLIC_URL:

$ PUBLIC_URL=/our/prefix npm run build:app
...
The project was built assuming it is hosted at /our/prefix/.
You can control this with the homepage field in your package.json.
...

Just let us know if there is a simpler way, thanks 🙇🏻

/cc @pwuersch