SSH Remote Launch Configuration

Generates a remote configuration for launching daemons over SSH, with the option of SSH tunnelling.

Usage

ssh_config(
  remotes,
  tunnel = FALSE,
  timeout = 10,
  command = "ssh",
  rscript = "Rscript"
)

Arguments

remotes

(character) URL(s) to SSH into using scheme 'ssh://', e.g. 'ssh://10.75.32.90:22' or 'ssh://nodename'. Port defaults to 22.

tunnel

(logical) whether to use SSH tunnelling. Requires url hostname '127.0.0.1' (use local_url() with tcp = TRUE). See SSH Tunnelling section.

timeout

(integer) maximum seconds for connection setup.

command

(character) shell command for launching daemons (e.g. "ssh"). NULL returns shell commands for manual deployment without launching.

rscript

(character) Rscript executable. Use full path if needed, or "Rscript.exe" on Windows.

Value

A list in the required format to be supplied to the remote argument of daemons() or launch_remote().

SSH Direct Connections

The simplest use of SSH is to execute the daemon launch command on a remote machine, for it to dial back to the host / dispatcher URL.

It is assumed that SSH key-based authentication is already in place. The relevant port on the host must also be open to inbound connections from the remote machine, and is hence suitable for use within trusted networks.

SSH Tunnelling

Use of SSH tunnelling provides a convenient way to launch remote daemons without requiring the remote machine to be able to access the host. Often firewall configurations or security policies may prevent opening a port to accept outside connections.

In these cases SSH tunnelling offers a solution by creating a tunnel once the initial SSH connection is made. For simplicity, this SSH tunnelling implementation uses the same port on both host and daemon. SSH key-based authentication must already be in place, but no other configuration is required.

To use tunnelling, set the hostname of the daemons() url argument to be '127.0.0.1'. Using local_url() with tcp = TRUE also does this for you. Specifying a specific port to use is optional, with a random ephemeral port assigned otherwise. For example, specifying 'tcp://127.0.0.1:5555' uses the local port '5555' to create the tunnel on each machine. The host listens to '127.0.0.1:5555' on its machine and the remotes each dial into '127.0.0.1:5555' on their own respective machines.

This provides a means of launching daemons on any machine you are able to access via SSH, be it on the local network or the cloud.

See also

cluster_config() for cluster resource manager launch configurations, or remote_config() for generic configurations.

Examples

# direct SSH example
ssh_config(c("ssh://10.75.32.90:222", "ssh://nodename"), timeout = 5)
#> $command
#> [1] "ssh"
#> 
#> $args
#> $args[[1]]
#> [1] "-o ConnectTimeout=5 -fTp 222" "10.75.32.90"                 
#> [3] "."                           
#> 
#> $args[[2]]
#> [1] "-o ConnectTimeout=5 -fTp 22" "nodename"                   
#> [3] "."                          
#> 
#> 
#> $rscript
#> [1] "Rscript"
#> 
#> $quote
#> [1] TRUE
#> 
#> $tunnel
#> [1] FALSE
#> 

# SSH tunnelling example
ssh_config(c("ssh://10.75.32.90:222", "ssh://nodename"), tunnel = TRUE)
#> $command
#> [1] "ssh"
#> 
#> $args
#> $args[[1]]
#> [1] "-o ConnectTimeout=10 -fTp 222" "10.75.32.90"                  
#> [3] "."                            
#> 
#> $args[[2]]
#> [1] "-o ConnectTimeout=10 -fTp 22" "nodename"                    
#> [3] "."                           
#> 
#> 
#> $rscript
#> [1] "Rscript"
#> 
#> $quote
#> [1] TRUE
#> 
#> $tunnel
#> [1] TRUE
#> 

if (FALSE) { # \dontrun{

# launch daemons on the remote machines 10.75.32.90 and 10.75.32.91 using
# SSH, connecting back directly to the host URL over a TLS connection:
daemons(
  n = 1,
  url = host_url(tls = TRUE),
  remote = ssh_config(c("ssh://10.75.32.90:222", "ssh://10.75.32.91:222"))
)

# launch 2 daemons on the remote machine 10.75.32.90 using SSH tunnelling:
daemons(
  n = 2,
  url = local_url(tcp = TRUE),
  remote = ssh_config("ssh://10.75.32.90", tunnel = TRUE)
)
} # }