Initial version

.gitignore

@@ -0,0 +1 @@
+.idea

Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1.12 AS build
+
+WORKDIR /go/src/app
+
+COPY . .
+RUN CGO_ENABLED=0 GO111MODULE=on go install .
+
+FROM scratch
+COPY --from=build /go/bin/github-release-redirector /github-release-redirector
+COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+
+ENTRYPOINT ["/github-release-redirector"]

LICENCE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) Chris Smith 2019
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,37 @@
+# github-release-redirector
+
+Small go application that listens for incoming HTTP requests and redirects
+to assets from the latest release published to a GitHub repository.
+
+## Usage
+
+```console
+$ go install .
+$ github-release-redirector -port 1234 -repo user/repo
+```
+
+or using docker:
+
+```console
+$ docker run -p 8080 csmith/github-release-redirector -repo user/repo
+```
+
+## Notes
+
+Releases are refreshed at startup and then once an hour.
+
+Assets are matched on their name, so an asset attached to the latest release
+named "myproject-installer-1.2.3.exe" will be available at the URL
+`/myproject-installer-1.2.3.exe`.
+
+Any url not mapped to an asset is responded to with a 404 not found error;
+if there is no latest release available all requests will respond with 500
+internal server error.
+
+The service listens only on HTTP, not HTTPS. For production use it should
+be placed behind an SSL-terminating proxy such as Traefik, Nginx or HAProxy.
+
+## Licence
+
+This software is released under the MIT licence. See the LICENCE file for
+full details.

go.mod

@@ -0,0 +1,8 @@
+module github.com/csmith/github-release-redirector
+
+go 1.12
+
+require (
+	github.com/google/go-github v17.0.0+incompatible
+	github.com/google/go-querystring v1.0.0 // indirect
+)

go.sum

@@ -0,0 +1,4 @@
+github.com/google/go-github v17.0.0+incompatible h1:N0LgJ1j65A7kfXrZnUDaYCs/Sf4rEjNlfyDHW9dolSY=
+github.com/google/go-github v17.0.0+incompatible/go.mod h1:zLgOLi98H3fifZn+44m+umXrS52loVEgC2AApnigrVQ=
+github.com/google/go-querystring v1.0.0 h1:Xkwi/a1rcvNg1PPYe5vI8GbeBY/jrVuDX5ASuANWTrk=
+github.com/google/go-querystring v1.0.0/go.mod h1:odCYkC5MyYFN7vkCjXpyrEuKhc/BUO6wN/zVPAxq5ck=

main.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"github.com/google/go-github/github"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+	"time"
+)
+
+var (
+	owner string
+	repo string
+	ctx context.Context
+	client *github.Client
+	release *github.RepositoryRelease
+)
+
+func fetchLatest() {
+	latest, _, err := client.Repositories.GetLatestRelease(ctx, owner, repo)
+	if err != nil {
+		log.Println("Error retrieving latest release", err)
+		return
+	}
+	release = latest
+}
+
+func serve(w http.ResponseWriter, request *http.Request) {
+	if release == nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = fmt.Fprint(w, "Unknown release")
+		return
+	}
+
+	for _, asset := range release.Assets {
+		if "/" + *asset.Name == request.RequestURI {
+			w.Header().Add("Location", *asset.BrowserDownloadURL)
+			w.WriteHeader(http.StatusTemporaryRedirect)
+			return
+		}
+	}
+
+	w.WriteHeader(http.StatusNotFound)
+	_, _ = fmt.Fprint(w, "Asset not found in release ", *release.Name)
+}
+
+func main() {
+	var fullRepo = flag.String("repo", "", "the repository to redirect releases for, in user/repo format")
+	var port = flag.Int("port", 8080, "the port to listen on for HTTP requests")
+	flag.Parse()
+
+	if strings.Count(*fullRepo, "/") != 1 {
+		log.Println("Repository must be specified in user/repo format")
+		return
+	}
+
+	repoParts := strings.Split(*fullRepo, "/")
+	owner = repoParts[0]
+	repo = repoParts[1]
+
+	client = github.NewClient(nil)
+
+	ticker := time.NewTicker(time.Hour)
+	go func() {
+		fetchLatest()
+		for range ticker.C {
+			fetchLatest()
+		}
+	}()
+
+
+	var cancel context.CancelFunc
+	ctx, cancel = context.WithCancel(context.Background())
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	signal.Notify(c, syscall.SIGTERM)
+
+	go func() {
+		for sig := range c {
+			cancel()
+			ticker.Stop()
+			log.Printf("Received %s, exiting.", sig.String())
+			os.Exit(0)
+		}
+	}()
+
+	log.Printf("Listing on :%d", *port)
+
+	server := &http.Server{
+		Addr:    fmt.Sprintf(":%d", *port),
+		Handler: http.HandlerFunc(serve),
+	}
+
+	err := server.ListenAndServe()
+	if err != nil {
+		log.Println("Error listening for requests on port ", port, err)
+	}
+}