Added source code

README.md

@@ -1,2 +1,10 @@
-# borg-gen-auth-keys
+### Generate an authorized_keys file:
 
+When working with borg serve in an automated environment, you should use an authorized_keys file that restricts the ssh sessions to use only borg, and only in the directory where the repo they should use lies in. This binary takes in a json file specifying the needed info and prints out the wanted authorized_keys file. 
+
+To generate that file, do this (assuming you have set up everything needed for go get, and $GOPATH/bin is in your $PATH):
+
+```bash
+go get git.jcg.re/jcgruenhage/borg-gen-auth-keys
+borg-gen-auth-keys yourjsonfile.json > ~/.ssh/authorized_keys  
+``` 

example.json

@@ -0,0 +1,13 @@
+{
+  "Folder": "/mnt/backupmount",
+  "Hosts":[
+    {
+      "Name": "host1",
+      "SSHKey": "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQC7ZvLoWZgh5eMDQXLEdWobkt/B8mnM2osEynF0boorifRNwztQHY3bKXTHjUlMnnWH+UvZ3aXH16M1QmyuNi4kLUTSMu4GSVsXMfknHRjgJ927Y/j5TCGXfOcfB0B4pcgHS3fVi1VMXXiZ1S/X8cbt1llXHfEC5eKutDeJkRer3w== SSH_KEY"
+    },
+    {
+      "Name": "host2",
+      "SSHKey": "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQDIgm31x6ETn4HwxBthe3m14s1Bp9p8sT5kC/XSijN6uPpUmuF2ciRGc5QLzsBJR6MAD45zg6Q9nLBZGBnSIZDNfSGA5sqAeoZVHm4vjQWxenqG7dlNFXlC1DIHzMxxDsDUPneyXGBemAvVwL9h4HEC4xhMQIAJfaZqSWuNzzqYWw== SSH_KEY"
+    }
+  ]
+}

main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"os"
+	"io/ioutil"
+	"encoding/json"
+	"fmt"
+)
+
+type Host struct {
+	Name string
+	SSHKey string
+}
+
+type HostList struct {
+	Folder string
+	Hosts []Host
+}
+
+func main() {
+	inputFilePath := os.Args[1]
+	dat, err := ioutil.ReadFile(inputFilePath)
+	check(err)
+	var hosts HostList
+	err = json.Unmarshal(dat, &hosts)
+	check(err)
+	for i := 0; i < len(hosts.Hosts); i++ {
+		fmt.Print("command=\"borg serve --restrict-to-path ")
+		fmt.Print(hosts.Folder)
+		fmt.Print("/")
+		fmt.Print(hosts.Hosts[i].Name)
+		fmt.Print("\",no-pty,no-agent-forwarding,no-port-forwarding,no-X11-forwarding,no-user-rc ")
+		fmt.Print(hosts.Hosts[i].SSHKey)
+		fmt.Print("\n")
+	}
+
+}
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}