Optionally prefix endpoints for easy versioning, reverse proxies.

Also added a default informative response when GETing '/'.

README.md

@@ -344,16 +344,27 @@ mkdir REGISTRY
 chmod 755 REGISTRY
 ```
 
-Finally, start the Gobbler by running the binary with a few arguments, including the UIDs of administrators:
+Finally, start the Gobbler by running the binary:
 
 ```sh
 ./gobbler \
     -staging STAGING \
     -registry REGISTRY \
     -admin ADMIN1,ADMIN2 \
-    -port PORT
+    -port PORT \
+    -prefix PREFIX
 ```
 
-Multiple Gobbler instances can target the same `REGISTRY` with different `STAGING`.
-This is useful for complex configurations where the same filesystem is mounted in multiple compute environments,
-whereby a separate Gobbler instance can be set up in each environment to enable uploads. 
+The following optional arguments can be used to fine-tune the Gobbler's behavior:
+
+- `-admin` contains a comma-separated list of administrator UIDs. 
+  This defaults to an empty strings, i.e., no administrators.
+- `-port` specifies the port for API calls.
+  This defaults to 8080.
+- `-prefix` adds an extra prefix to all endpoints, e.g., to disambiguate between versions.
+  For example, a prefix of `api/v2` would change the list endpoint to `/api/v2/list`.
+  This defaults to an empty string, i.e., no prefix.
+
+Multiple Gobbler instances can safely target the same `REGISTRY` with different `STAGING`.
+This is useful for complex HPC configurations where the same filesystem is mounted in multiple compute environments;
+a separate Gobbler instance can be set up in each environment to enable uploads.

main.go

@@ -136,10 +136,11 @@ func (a *activeRegistry) Remove(path string) {
 /***************************************************/
 
 func main() {
-    spath := flag.String("staging", "", "Path to the staging directory.")
-    rpath := flag.String("registry", "", "Path to the registry.")
-    mstr := flag.String("admin", "", "Comma-separated list of administrators.")
-    port := flag.Int("port", 8080, "Port to listen to API requests.")
+    spath := flag.String("staging", "", "Path to the staging directory")
+    rpath := flag.String("registry", "", "Path to the registry")
+    mstr := flag.String("admin", "", "Comma-separated list of administrators (default \"\")")
+    port := flag.Int("port", 8080, "Port to listen to API requests")
+    prefix := flag.String("prefix", "", "Prefix to add to each endpoint, excluding the first and last slashes (default \"\")")
     flag.Parse()
 
     if *spath == "" || *rpath == "" {
@@ -163,8 +164,13 @@ func main() {
 
     actreg := newActiveRegistry(11)
 
+    endpt_prefix := *prefix
+    if endpt_prefix != "" {
+        endpt_prefix = "/" + endpt_prefix
+    }
+
     // Creating an endpoint to trigger jobs.
-    http.HandleFunc("POST /new/{path}", func(w http.ResponseWriter, r *http.Request) {
+    http.HandleFunc("POST " + endpt_prefix + "/new/{path}", func(w http.ResponseWriter, r *http.Request) {
         path := r.PathValue("path")
         log.Println("processing " + path)
 
@@ -244,9 +250,10 @@ func main() {
 
     // Creating an endpoint to list and serve files, for remote access to the registry.
     fs := http.FileServer(http.Dir(globals.Registry))
-    http.Handle("GET /fetch/", http.StripPrefix("/fetch/", fs))
+    fetch_endpt := endpt_prefix + "/fetch/"
+    http.Handle("GET " + fetch_endpt, http.StripPrefix(fetch_endpt, fs))
 
-    http.HandleFunc("GET /list", func(w http.ResponseWriter, r *http.Request) {
+    http.HandleFunc("GET " + endpt_prefix + "/list", func(w http.ResponseWriter, r *http.Request) {
         listing, err := listFilesHandler(r, globals.Registry)
         if err != nil {
             dumpHttpErrorResponse(w, err, "list request") 
@@ -255,11 +262,15 @@ func main() {
         }
     })
 
-    // Creating a useful health-check endpoint. 
-    http.HandleFunc("GET /info", func(w http.ResponseWriter, r *http.Request) {
+    // Creating some useful endpoints. 
+    http.HandleFunc("GET " + endpt_prefix + "/info", func(w http.ResponseWriter, r *http.Request) {
         dumpJsonResponse(w, http.StatusOK, map[string]string{ "staging": staging, "registry": globals.Registry }, "info request")
     })
 
+    http.HandleFunc("GET " + endpt_prefix + "/", func(w http.ResponseWriter, r *http.Request) {
+        dumpJsonResponse(w, http.StatusOK, map[string]string{ "name": "gobbler API", "url": "https://github.com/ArtifactDB/gobbler" }, "default request")
+    })
+
     // Adding a per-day job that purges various old files.
 	ticker := time.NewTicker(time.Hour * 24)
 	defer ticker.Stop()