Dockerfile

FROM ubuntu:14.04

WORKDIR /data

ENTRYPOINT \
        ./Runner.sh

Downloader.go

package main

import (
    "flag"
    "fmt"
    "os"
    "log"
    "net/http"
    "io"
)

var (
    Url string
    FileName string
)

func init() {
    flag.StringVar(&Url, "url", "", "The URL to download from.")
    flag.StringVar(&FileName, "file", "file", "The file to download to.")
    flag.Parse()
}

func main() {
    downloaded := download(FileName, Url)
    if !downloaded {
        fmt.Println("Couldn't download the file!")
        os.Exit(1)
        return
    }
    fmt.Println("Downloaded the file to", FileName)
}

func download(filename, dl string) bool {
    file, err := os.Create(filename)
    fmt.Println("Tried creating", filename)

    if err != nil {
        fmt.Println("Couldn't create. Statting.")
        _, err := os.Stat(filename)
        if os.IsNotExist(err) {
            log.Fatal(err)
        }
        fmt.Println("Created anyways, it seems.")
    }
    defer file.Close()

    // File now exists.
    resp, err := http.Get(dl)
    fmt.Println("Trying to download!")
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    bytes, err := io.Copy(file, resp.Body)
    fmt.Println("Trying to copy!")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Successfully copied", bytes, "bytes in total!")

    return true
}

Runner.sh

#!/bin/bash

./Downloader -file CoalesceBot.jar -url "http://vpswithjenkins/job/CoalesceBot/lastSuccessfulBuild/artifact/target/CoalesceBot.jar"

tools/java/bin/java -Xms64M -Xmx96M -jar CoalesceBot.jar bot-token github-token