improve docker container usage (#1704)

* Update Go build version for Docker container

* Explicitly specify copy target

* Set ENTRYPOINT

* Move binary to /bin

* Add docker usage instructions to the README

* Set /code as the default WORKDIR

---------

Co-authored-by: Norman Gehrsitz <git@gehrsitz.eu>

Dockerfile

@@ -1,7 +1,7 @@
 # Dockerfile References: https://docs.docker.com/engine/reference/builder/
 
 # Start from the latest golang base image
-FROM golang:1.18.3-alpine as builder
+FROM golang:1.20-alpine as builder
 
 # Set the Current Working Directory inside the container
 WORKDIR /app
@@ -22,7 +22,9 @@ RUN CGO_ENABLED=0 GOOS=linux go build -v -a -installsuffix cgo -o swag cmd/swag/
 ######## Start a new stage from scratch #######
 FROM scratch
 
-WORKDIR /root/
+WORKDIR /code/
 
 # Copy the Pre-built binary file from the previous stage
-COPY --from=builder /app/swag .
+COPY --from=builder /app/swag /bin/swag
+
+ENTRYPOINT ["/bin/swag"]

README.md

@@ -51,12 +51,17 @@ Swag converts Go annotations to Swagger Documentation 2.0. We've created a varie
 
 1. Add comments to your API source code, See [Declarative Comments Format](#declarative-comments-format).
 
-2. Download swag by using:
+2. Install swag by using:
 ```sh
 go install github.com/swaggo/swag/cmd/swag@latest
 ```
 To build from source you need [Go](https://golang.org/dl/) (1.17 or newer).
 
+Alternatively you can run the docker image:
+```sh
+docker run --rm -v $(pwd):/code ghcr.io/swaggo/swag:latest
+```
+
 Or download a pre-compiled binary from the [release page](https://github.com/swaggo/swag/releases).
 
 3. Run `swag init` in the project's root folder which contains the `main.go` file. This will parse your comments and generate the required files (`docs` folder and `docs/docs.go`).