来自Docker容器的空响应

I'm trying to deploy a simple example webserver on a Droplet instance from Digital Ocean. This example works on my development machine (Windows) but not on my server (Ubuntu).

Tried from inside the Droplet:

curl localhost:8080

Obtained:

curl: (52) Empty reply from server

docker ps shows:

CONTAINER ID        IMAGE                    COMMAND              CREATED             STATUS              PORTS                            NAMES
9325cfbc60d5        myapp.com                "/bin/sh -c ./app"   36 minutes ago      Up 36 minutes       80/tcp, 0.0.0.0:8080->8080/tcp   myappcom_website_1

Application:

package main

import (
    "net/http"
    "strings"
)

func sayHello(w http.ResponseWriter, r *http.Request) {
    message := r.URL.Path
    message = strings.TrimPrefix(message, "/")
    message = "Hello " + message

    w.Write([]byte(message))
}

func main() {
    http.HandleFunc("/", sayHello)
    if err := http.ListenAndServe(":8080", nil); err != nil {
        panic(err)
    }
}

Dockerfile:

# Build stage
FROM golang:alpine AS builder
WORKDIR /go/src/app
COPY . .
RUN apk add --no-cache curl 
RUN curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
RUN dep ensure
RUN go install 

# Final stage
FROM alpine:latest
COPY --from=builder /go/bin/app /app
ENTRYPOINT ./app
LABEL Name=myapp.com Version=0.0.1
EXPOSE 8080:8080

docker-compose.yml:

version: '3.6'

services:
  website:
    image: myapp.com
    build: .
    ports:
      - 8080:8080

Why?

EDIT: I noted that if I docker ps on my dev machine, under "ports" it shows 0.0.0.0:8080->8080/tcp, without the port 80 like in the droplet. I didn't expose port 80 on my droplet, so I wonder why it is showed there. Maybe digital ocean docker image is messing something up?