Merge pull request #10 from NBISweden/instructions

Add some basic instructions for usage

README.md

@@ -4,16 +4,48 @@ This repository provides a FUSE file system driver for the sensitive data
 archive. The intended use is to provide an easy way to use the archive
 off-platform.
 
-## FUSE driver
+## About
 
-This should work as user (privilegeless) installation on any modern system
-providing the FUSE stack (i.e. fusermount3).
+### FUSE driver
+
+This should work as user (without additional privileges) installation on any
+modern system providing the FUSE stack (i.e. `fusermount3`).
 
 This should be usable. There are some possible improvements regarding cache
 handling that can be done and it hasn't currently been tested for very large
 datasets
 
-## CSI
+### CSI
 
 We also aim to provide a CSI to allow usage with kubernetes. This is still
 work in progress and should not be expected to be usable at this point in time.
+
+## Usage
+
+To be usable, you need to have been granted access to datasets, for bigpicture
+you can view available datasets and apply for access in
+[REMS](https://bp-rems.sd.csc.fi/).
+
+Once you have been granted access, you can download a configuration file with
+access credentials from the
+[login site](https://login.bp.nbis.se/).
+
+Armed with you configuration (e.g. in `~/Download/s3cmd.conf`), you can launch
+`sdafs` at `/where/you/want/to/mount` as so:
+
+```bash
+sdafs --credentialsfile ~/Download/s3cmd.conf /where/you/want/to/mount
+```
+
+### Troubleshooting
+
+By default, `sdafs` will daemonize after some rudimentary checks. After that,
+additional messages can be seen in the log file (`sdafs.log` in the current
+directory unless overridden when running in the background). Alternatively,
+`sdafs` can be run without detaching with by passing `--foreground`.
+
+### Permissions
+
+By default, `sdafs` will not allow access from other users. For use cases where
+that is not enough (e.g. running some tool in a container solution), the flag
+`--open` will allow access from all users.

cmd/sdafs/main.go

@@ -112,6 +112,19 @@ func detachIfNeeded(c mainConfig) {
 	}
 }
 
+func checkMountDir(m mainConfig) {
+	st, err := os.Stat(m.mountPoint)
+
+	if err != nil {
+		log.Fatalf("Error while checking desired mount point %s: %v",
+			m.mountPoint, err)
+	}
+
+	if !st.IsDir() {
+		log.Fatalf("Error while checking mount point %s: not a directory", m.mountPoint)
+	}
+}
+
 func main() {
 	c := getConfigs()
 	mountConfig := &fuse.MountConfig{
@@ -122,14 +135,16 @@ func main() {
 		VolumeName:                fmt.Sprintf("SDA mount of %s", c.sdafsconf.RootURL),
 	}
 
-	repointLog(c)
-	detachIfNeeded(c)
+	checkMountDir(c)
 
 	fs, err := sdafs.NewSDAfs(c.sdafsconf)
 	if err != nil {
 		log.Fatalf("Error while creating sda fs: %v", err)
 	}
 
+	repointLog(c)
+	detachIfNeeded(c)
+
 	mount, err := fuse.Mount(c.mountPoint, fs.GetFileSystemServer(), mountConfig)
 	if err != nil {
 		log.Fatalf("Mount of sda at %s failed: %v", c.sdafsconf.RootURL, err)