How to copy files between nodes¶

The following defines an scp-based remote-copy application, and a node prototype using it to copy an arbitrary file to a chosen remote destination.

 1 defApplication('Scp', 'Scp') {|a|
 2         a.name = "Scp" 
 3         a.version(0, 0, 1)
 4         a.path = "/usr/bin/scp" 
 5         a.defProperty('source', "File to copy", nil,  {:order => 1, :dynamic => false, :type => :string, :use_name => false})
 6         a.defProperty('destination', "Destination to copy the source to", nil,  {:order => 2, :dynamic => false, :type => :string, :use_name => false})
 7 }
 8 defPrototype('resultGetter', 'resultGetter'){|a|
 9         a.defProperty('file', 'File to retrieve')
10         a.defProperty('server', 'Server to copy the file to')
11         a.addApplication("Scp", "getresults"){ |listener|
12                 listener.bindProperty('source', 'file')
13                 listener.bindProperty('destination','server')
14         }
15 }

The prototype can then be used for nodes (note the use of the Experiment ID to avoid collisions on the remote machine).

1 defGroup('SenderResults', property.src {|node|
2         node.prototype("resultGetter", { 'server' => "USER@SERVER:/tmp", 'file' => "/tmp/#{Experiment.ID}.Sender.pcap"})
3 }
4  defGroup('ReceiverResults', property.dst){|node|
5         node.prototype("resultGetter", { 'server' => "USER@SERVER:/tmp", 'file' => "/tmp/#{Experiment.ID}.Receiver.pcap"})
6 }
7 defGroup('ResultGetters', ["SenderResults","ReceiverResults"])

Finally, the files can be copied, e.g. at the end of the experiment.

 1 whenAllInstalled() {|node|
 2 
 3         #
 4         # [Run the actual experiment here]
 5         #
 6 
 7         # Retrieve the results and wait to allow them to finish
 8         group("ResultGetters").startApplications      
 9         wait 10
10 
11         Experiment.done
12 }

You also need to have distributed SSH keys properly so scp doesn't need a password. This can be quiclky done, from the experimentation node as follows.

root@node9:~# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
d4:6c:c1:20:6d:a1:df:dd:44:a4:96:80:de:47:16:b8 root@node9
The key's randomart image is:
+--[ RSA 2048]----+
|      ..o=o..oo  |
|       o+oooo+   |
|      .o..+++ .  |
|       o.oEo.o   |
|        S ... .  |
|                 |
|                 |
|                 |
|                 |
+-----------------+
root@node9:~# ssh-copy-id USER@SERVER:
The authenticity of host 'SERVER (SERVER)' can't be established.
RSA key fingerprint is 75:24:1d:06:ec:1a:e5:df:7a:34:f4:71:18:ce:2a:0a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'SERVER' (RSA) to the list of known hosts.
Error reading response length from authentication socket.
USER@SERVER's password: 
Now try logging into the machine, with "ssh 'USER@1SERVER'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

Of course, the fingerprint of the generated key will vary.