SwaggerUI is not working in Docker, but works locally. Only the SwaggerUI throws a `404 Not Found`

[kerkmann]

Okay, I know this sounds weird ... but: The SwaggerUI is not working inside of Docker. ^^"

Let me explain what I did. When I write down everything like in the example for axum and I start the application with cargo run, I can see the swagger-ui and also see the /docs/openapi.json file.
Now the interesting part, when I compile the code inside docker and provide it inside docker only the swagger-ui endpoint (/docs in this example) is returning a 404 Not Found. But the interesting thing is, all other endpoints are working... Including the /docs/opanapi.json endpoint.
So, only the swagger-ui isn't working inside Docker. ^^"

I thought "maybe it's a compiled problem", so I copied the locally build binary (which worked on the machine and showed the swagger-ui) into the docker container, started it and "boom", no swagger-ui. ^^"
It's so weird that every endpoint is working, also the openapi.json endpoint (which shows the full generated openapi json), but only the swagger-ui HTML-Page is not working. There is really no difference inside the Docker container and my local machine (like I said, I copied the binary to prove my assumption).
I also tried bigger OS containers like ubuntu and smaller ones like alpine, in all containers every endpoint is working, except the swagger-ui. :(

Does someone have an idea what I could test/think of? I'm getting out of ideas. ^^"

[omarmhaimdat]

I am experiencing the same issue

[juhaku]

That is weird indeed 😮 But based only on this message it is really hard to tell what is going wrong and where. 🤔

I tried to build the todo-axum in in the examples folder as:

1. I build the app with command

cargo build --release --target=x86_64-unknown-linux-musl

2. I added a dockerfile like this:

FROM alpine:3.17

RUN mkdir /opt/app

COPY target/x86_64-unknown-linux-musl/release/todo-axum /opt/app

EXPOSE 8080

CMD [ "/opt/app/todo-axum" ]

3. Run docker build command docker build -t todo-axum:test .
4. Run the container docker run -p 8080:8080 todo-axum:test
5. Went to localhost:8080/swagger-ui/ with my browser and Swagger UI showed up.

If you build in debug mode then utoipa-swagger-ui needs the debug-embed flag to be enabled. That is, RustEmbed itself does not embed stuff to the binary in debug builds by default. See more here https://github.com/pyrossh/rust-embed#features.

Also not that you have correct target. that linux-musl is generic linux target meant to be used within docker containers.

Hope these helps.

[kerkmann]

Okay, that explains a lot .... you are totally right, it's working with a release build. :)

I created the build in debug mode, and it seems like that the debug-embed flag is not enabled inside Docker. ^^"

Maybe it makes sense that we pinpoint that "issue" out in the Readme, thank you very much! <3

[kerkmann]

I've created a small documentation change to pinpoint it better in the README. Maybe it will help out. :3

[juhaku]

Maybe it makes sense that we pinpoint that "issue" out in the Readme, thank you very much! <3

Yeah, actually there is slight hint towards this in utoipa-swagger-ui README.md but it is not obivous to the eye.

[kerkmann]

Yeah, actually there is slight hint towards this in utoipa-swagger-ui README.md but it is not obivous to the eye.

Ah yeah, now I see what you mean. It wasn't quite obvious to me and two other people. So spending hours investigating that issue could be solved by pinpointing it out. :)

[juhaku]

Ah yeah, now I see what you mean. It wasn't quite obvious to me and two other people. So spending hours investigating that issue could be solved by pinpointing it out. :)

True 🙂

[juhaku]

Relates to #268