Fix NFS VolumeStore FQDN not working (#8244)

* Fix NFS VolumeStore FQDN not working

When docker using a nfs VolumeStore as a volume, the mount action will fail if the nfs-server url is a FQDN. A dotted ip url works well. When the linux syscall mount(source, target, flag, mountOptions) using for nfs mount, its mountOptions should contain 'addr=serverip' and the serverip must be an ip(ps. the url in source is useless).

Thus the fix resolve the FQDN and give its mountOptions the 'addr=ip'. The mountOptions is generated as 'addr=host' at CreateMountSpec when creating the endpointVM. The fix choose
to do the resolve just before the mounting action.

Resolve: #8043

lib/tether/ops_linux.go

@@ -960,14 +960,25 @@ func (t *BaseOperations) MountTarget(ctx context.Context, source url.URL, target
 	}
 	rawSource.WriteString(source.Path)
 
-	// NOTE: by default we are supporting "NOATIME" and it can be configurable later. this must be specfied as a flag.
-	// Additionally, we must parse out the "ro" option and supply it as a flag as well for this flavor of the mount call.
-	if err := Sys.Syscall.Mount(rawSource.String(), target, nfsFileSystemType, syscall.MS_NOATIME, mountOptions); err != nil {
-		log.Errorf("mounting %s on %s failed: %s", source.String(), target, err)
+	ips, err := net.LookupIP(source.Hostname())
+	if err != nil {
+		log.Errorf("failing to resolve %s. mounting %s on %s failed: %s", source.Hostname(), source.String(), target, err)
 		return err
 	}
-
-	return nil
+	for _, ip := range ips {
+		//NOTE: the mountOptions of syscall mount only accept addr=ip. addr=FQDN doesn't work
+		//We resolve the ip address nearest the mounting action.
+		mountOptionsIP := strings.Replace(mountOptions, "addr="+source.Hostname(), "addr="+ip.String(), -1)
+		// NOTE: by default we are supporting "NOATIME" and it can be configurable later. this must be specfied as a flag.
+		// Additionally, we must parse out the "ro" option and supply it as a flag as well for this flavor of the mount call.
+		if err = Sys.Syscall.Mount(rawSource.String(), target, nfsFileSystemType, syscall.MS_NOATIME, mountOptionsIP); err != nil {
+			log.Debugf("mounting %s with resolved ip: %s on %s failed: %s", source.String(), ip.String(), target, err)
+		} else {
+			return nil
+		}
+	}
+	log.Errorf("mounting %s on %s failed: %s", source.String(), target, err)
+	return err
 }
 
 // CopyExistingContent copies the underlying files shadowed by a mount on a directory

tests/test-cases/Group1-Docker-Commands/1-19-Docker-Volume-Create.md

@@ -29,6 +29,7 @@ This test requires that a vSphere server is running and available
 15. Create container with a named volume and verify that base image files are copied to the named volume
 16. Create container with a named volume. Modify the copied image file. Remount the volume in a new container.
 17. Run container with a volume, and run another container with same volume
+18. Create a nfs server, get its fqdn and add a fqdn-based nfs VolumeStore to VCH, and run a container to mount the volume of this VolumeStore.
 
 # Expected Outcome:
 * Steps 2 and 3 should complete successfully and return the name of the volume created, you should then be able to see the volume has been created
@@ -58,6 +59,7 @@ Error response from daemon: create test???: "test???" includes invalid character
 * Step 15 should result in success and print data in the volume
 * Step 16 should result in success and the second container should contain the modified file contents
 * Step 17 should result in error with message `devices <volume id> in use`
+* Step 18 should result in success and print data in the volume
 
 # Possible Problems:
 * VIC requires you to specify storage on creation of the VCH that volumes can be created from, so when installing the VCH make sure to specify this parameter: --volume-store=

tests/test-cases/Group1-Docker-Commands/1-19-Docker-Volume-Create.robot

@@ -217,3 +217,21 @@ Docker volume conflict in new container
     Should Be Equal As Integers  ${rc}  125
     Should Contain  ${output}  Error response from daemon
     Should Contain  ${output}  device ${volID} in use
+
+Docker volume create fqdn-based nfs datastore
+    ${rc}  ${output}=  Run And Return Rc And Output  docker %{VCH-PARAMS} volume create --name nfs-vol --opt Capacity=5G
+    Should Be Equal As Integers  ${rc}  0
+    ${rc}  ${output}=  Run And Return Rc And Output  docker %{VCH-PARAMS} run -d -v nfs-vol:/mnt/nfs-vol --net public --name nfs-server -p 111:111 -p 2049:2049 -p 32767:32767 -p 32768:32768 -e EXPORT_FOLDER=/mnt/nfs-vol bensdoings/nfs-server
+    Should Be Equal As Integers  ${rc}  0
+    ${ip}=  Get Container IP  %{VCH-PARAMS}  nfs-server  public
+    ${rc}  ${fqdn}=  Run And Return Rc And Output  docker %{VCH-PARAMS} run --net public ${busybox} nslookup ${ip} | awk -F'${ip} ' '/${ip} /{print $2}'
+    Should Be Equal As Integers  ${rc}  0
+    ${output}=  Run  bin/vic-machine-linux configure --name=%{VCH-NAME} --target=%{TEST_URL} --thumbprint=%{TEST_THUMBPRINT} --user=%{TEST_USERNAME} --password=%{TEST_PASSWORD} --timeout %{TEST_TIMEOUT} --volume-store=%{TEST_DATASTORE}/%{VCH-NAME}-VOL:default --volume-store=\'nfs://${fqdn}/mnt/nfs-vol?uid=0&gid=0&proto=tcp&port=2049:nfsfqdn\'
+    Should Contain  ${output}  Completed successfully
+    ${rc}  ${output}=  Run And Return Rc And Output  docker %{VCH-PARAMS} volume create --name nfs-vol-fqdn --opt VolumeStore=nfsfqdn
+    Should Be Equal As Integers  ${rc}  0
+    ${rc}  ${output}=  Run And Return Rc And Output  docker %{VCH-PARAMS} run -v nfs-vol-fqdn:/data ${busybox} sh -c "echo fqdn > /data/fqdn"
+    Should Be Equal As Integers  ${rc}  0
+    ${rc}  ${output}=  Run And Return Rc And Output  docker %{VCH-PARAMS} run -v nfs-vol-fqdn:/data ${busybox} sh -c "cat /data/fqdn"
+    Should Be Equal As Integers  ${rc}  0
+    Should Contain  ${output}  fqdn