From 971452bda26fc20bfff3c07f6203d61fd4ca0df8 Mon Sep 17 00:00:00 2001
From: Tim Pierce <twp@curoverse.com>
Date: Fri, 21 Mar 2014 17:54:25 -0400
Subject: [PATCH] Initial checkin: simple Keep server handling block reads
 only. (refs #2291)

---
 services/keep/keep.go | 80 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 services/keep/keep.go

diff --git a/services/keep/keep.go b/services/keep/keep.go
new file mode 100644
index 0000000000..cec20be869
--- /dev/null
+++ b/services/keep/keep.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/gorilla/mux"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+)
+
+const DEFAULT_PORT = 25107
+
+var KeepVolumes []string
+
+func main() {
+	// Look for local keep volumes.
+	KeepVolumes = FindKeepVolumes()
+	if len(KeepVolumes) == 0 {
+		log.Fatal("could not find any keep volumes")
+	}
+	for _, v := range KeepVolumes {
+		log.Println("keep volume:", v)
+	}
+
+	// Set up REST handlers.
+	rest := mux.NewRouter()
+	rest.HandleFunc("/{hash}", GetBlock).Methods("GET")
+	http.Handle("/", rest)
+
+	port := fmt.Sprintf(":%d", DEFAULT_PORT)
+	http.ListenAndServe(port, nil)
+}
+
+func GetBlock(w http.ResponseWriter, req *http.Request) {
+	hash := mux.Vars(req)["hash"]
+
+	// Attempt to read the requested hash from a keep volume.
+	for _, vol := range KeepVolumes {
+		path := fmt.Sprintf("%s/%s/%s", vol, hash[0:3], hash)
+		if f, err := os.Open(path); err == nil {
+			io.Copy(w, f)
+			break
+		} else {
+			log.Printf("%s: reading block %s: %s\n", vol, hash, err)
+		}
+	}
+}
+
+// FindKeepVolumes
+//     Returns a list of Keep volumes mounted on this system.
+//
+//     A Keep volume is a normal or tmpfs volume with a /keep
+//     directory at the top level of the mount point.
+//
+func FindKeepVolumes() []string {
+	vols := make([]string, 0)
+
+	if f, err := os.Open("/proc/mounts"); err != nil {
+		log.Fatal("could not read /proc/mounts: ", err)
+	} else {
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			args := strings.Fields(scanner.Text())
+			dev, mount := args[0], args[1]
+			if (dev == "tmpfs" || strings.HasPrefix(dev, "/dev/")) && mount != "/" {
+				keep := mount + "/keep"
+				if st, err := os.Stat(keep); err == nil && st.IsDir() {
+					vols = append(vols, keep)
+				}
+			}
+		}
+		if err := scanner.Err(); err != nil {
+			log.Fatal(err)
+		}
+	}
+	return vols
+}
-- 
2.30.2