Initial checkin: simple Keep server handling block reads only. (refs #2291)

diff --git a/services/keep/keep.go b/services/keep/keep.go
new file mode 100644 (file)
index 0000000..cec20be
--- /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
+}