This is a server application that fetches recommended transaction fee data from a specified mempool's instance API and serves it in a formatted JSON response that's expected by umbrelOS 1.0+ to display the widget.
The server is built using the bun JavaScript framework and is containerized as a distroless Docker image for umbrelOS.
The server application is defined in index.js. It fetches fee data from the upstream API, formats the data into a specific JSON structure, and serves the formatted data at the /widgets/fees endpoint.
If the upstream API request fails for any reason, the handler returns a default response with placeholder fee data.
The Dockerfile defines a multi-stage Docker build process. The first stage uses the official bun image to compile the server application into a binary. The second stage uses a distroless glibc image to create a minimal Docker image. The compiled binary is copied from the first stage into the second stage, and the binary is run when a container is started from the image.
The Dockerfile uses build arguments to target specific architectures (x86 and arm64) during the build process. The TARGETPLATFORM argument is used to select the appropriate bun target for the architecture.
To run the server, you can build and run a Docker container using the Dockerfile. The server will start on port 3000 and will serve the fee data at the /widgets/fees endpoint.
Note: You will need to set the
MEMPOOL_API_URLenvironment variable to the URL of your upstream API before starting the server. If you don't have a local mempool instance, you may set it tohttps://mempool.space/api/v1/fees/recommended.
If you wish to run the server locally for development, simply install bun on your system and run bun index.js in the project's directory.