ssh-python Parallel Client¶
API documentation for the ssh-python
(libssh
) based parallel client.
-
class
pssh.clients.ssh.parallel.
ParallelSSHClient
(hosts, user=None, password=None, port=22, pkey=None, cert_file=None, num_retries=3, timeout=None, pool_size=100, allow_agent=True, host_config=None, retry_delay=5, forward_ssh_agent=False, gssapi_auth=False, gssapi_server_identity=None, gssapi_client_identity=None, gssapi_delegate_credentials=False, identity_auth=True)¶ ssh-python based parallel client.
- Parameters
hosts (list(str)) – Hosts to connect to
user (str) – (Optional) User to login as. Defaults to logged in user
password (str) – (Optional) Password to use for login. Defaults to no password
port (int) – (Optional) Port number to use for SSH connection. Defaults to 22.
pkey (str) – Private key file path to use. Path must be either absolute path or relative to user home directory like
~/<path>
.cert_file (str) – Public key signed certificate file to use for authentication. The corresponding private key must also be provided via
pkey
parameter. For examplepkey='id_rsa', cert_file='id_rsa-cert.pub'
for RSA signed certificate. Path must be absolute or relative to user home directory.num_retries (int) – (Optional) Number of connection and authentication attempts before the client gives up. Defaults to 3.
retry_delay (int) – Number of seconds to wait between retries. Defaults to
pssh.constants.RETRY_DELAY
timeout (float) –
(Optional) Individual SSH client timeout setting in seconds passed on to each SSH client spawned by ParallelSSHClient.
This controls timeout setting of socket operations used for SSH sessions on a per session basis meaning for each individual SSH session.
Defaults to OS default - usually 60 seconds.
Parallel functions like run_command and join have a cummulative timeout setting that is separate to and not affected by self.timeout.
pool_size (int) – (Optional) Greenlet pool size. Controls concurrency, on how many hosts to execute tasks in parallel. Defaults to 100. Overhead in event loop will determine how high this can be set to, see scaling guide lines in project’s readme.
host_config (dict) – (Optional) Per-host configuration for cases where not all hosts use the same configuration.
allow_agent (bool) – (Optional) set to False to disable connecting to the system’s SSH agent. Currently unused - always off.
identity_auth (bool) – (Optional) set to False to disable attempting to authenticate with default identity files from pssh.clients.base_ssh_client.BaseSSHClient.IDENTITIES
proxy_host (str) – (Optional) SSH host to tunnel connection through so that SSH clients connect to host via client -> proxy_host -> host
proxy_port (int) – (Optional) SSH port to use to login to proxy host if set. Defaults to 22.
proxy_user (str) – (Optional) User to login to
proxy_host
as. Defaults to logged in user.proxy_password (str) – (Optional) Password to login to
proxy_host
with. Defaults to no password.proxy_pkey (Private key file path to use.) – (Optional) Private key file to be used for authentication with
proxy_host
. Defaults to available keys from SSHAgent and user’s SSH identities.forward_ssh_agent (bool) – (Optional) Turn on SSH agent forwarding - equivalent to ssh -A from the ssh command line utility. Defaults to False if not set. Currently unused meaning always off.
gssapi_server_identity (str) – Set GSSAPI server identity.
gssapi_server_identity – Set GSSAPI client identity.
gssapi_delegate_credentials (bool) – Enable/disable server credentials delegation.
- Raises
pssh.exceptions.PKeyFileError
on errors finding provided private key.
-
run_command
(command, sudo=False, user=None, stop_on_errors=True, use_pty=False, host_args=None, shell=None, encoding='utf-8', timeout=None, read_timeout=None, return_list=False)¶ Run command on all hosts in parallel, honoring self.pool_size, and return output.
This function will block until all commands have been received by remote servers and then return immediately.
More explicitly, function will return after connection and authentication establishment in the case of on new connections and after execute commands have been accepted by successfully established SSH channels.
Any connection and/or authentication exceptions will be raised here and need catching unless
run_command
is called withstop_on_errors=False
in which case exceptions are added to individual host output instead.- Parameters
command (str) – Command to run
sudo (bool) – (Optional) Run with sudo. Defaults to False
user (str) – (Optional) User to run command as. Requires sudo access for that user from the logged in user account.
stop_on_errors (bool) – (Optional) Raise exception on errors running command. Defaults to True. With stop_on_errors set to False, exceptions are instead added to output of run_command. See example usage below.
shell (str) – (Optional) Override shell to use to run command with. Defaults to login user’s defined shell. Use the shell’s command syntax, eg shell=’bash -c’ or shell=’zsh -c’.
use_pty (bool) – (Optional) Enable/Disable use of pseudo terminal emulation. Defaults to
False
host_args (tuple or list) – (Optional) Format command string with per-host arguments in
host_args
.host_args
length must equal length of host list -pssh.exceptions.HostArgumentError
is raised otherwiseencoding (str) – Encoding to use for command string and output. Must be valid Python codec
read_timeout (float) – (Optional) Timeout in seconds for reading from stdout or stderr. Defaults to self.timeout. Reading from stdout/stderr will raise
pssh.exceptions.Timeout
aftertimeout
number seconds if remote output is not ready.timeout (float) – Deprecated - use read_timeout. Same as read_timeout and kept for backwards compatibility - to be removed in future release.
return_list (bool) – No-op - list of
HostOutput
always returned. Parameter kept for backwards compatibility - to be removed in future releases.
- Return type
list(
pssh.output.HostOutput
)- Raises
pssh.exceptions.AuthenticationError
on authentication error- Raises
pssh.exceptions.UnknownHostError
on DNS resolution error- Raises
pssh.exceptions.ConnectionError
on error connecting- Raises
pssh.exceptions.HostArgumentError
on number of host arguments not equal to number of hosts- Raises
TypeError
on not enough host arguments for cmd string format- Raises
KeyError
on no host argument key in arguments dict for cmd string format- Raises
pssh.exceptions.ProxyError
on errors connecting to proxy if a proxy host has been set.- Raises
pssh.exceptions.Timeout
on timeout starting command.- Raises
Exceptions from
ssh.exceptions
for all other specific errors.