Difference between revisions of "Satori/SSHModuleProposal"
< Satori
Ziad Sawalha (talk | contribs) (→Implementation) |
Ziad Sawalha (talk | contribs) (→Implementation) |
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− | We considered the following to stay within pylint's | + | We considered the following to stay within pylint's max 5 argument rule, but we decided to break the rule for practicality... |
# Simplest use case | # Simplest use case |
Latest revision as of 17:25, 10 March 2014
SSH Module Proposal
- Implement an SSH wrapper module to enable logging on to servers so we can do data plane discovery.
- This wiki page defines the full specification for the ssh-module blueprint.
Interface
from satori import ssh if proxy_ip: proxy = ssh.connect(proxy_ip, port=22, username=proxy_user, password=proxy_pass) else: proxy = None connection = ssh.connect("10.1.1.20", username="root", password="Password", key=None, proxy=proxy) output = connection.remote_execute("sudo echo hello", with_exit_code=True) >>> {'stdout': 'hello', 'stderr': '', 'exit_code': 0}
Requirements
Support the following logins:
- password/username
- private key/username
- private key file/username
- for all the above logins, the module should support using a proxy (a.k.a. bastion)
Primary class methods:
- remote_execute(): to execute a remote command and return stderr and stdout
- test_connection(): to test that a connection can be made
Additionally:
- Implement an instance property,
platform_info
, that will return the remote host's platform info using (python >=2.4)'s platform module
Implementation
- Use paramiko and extend its SSHClient class. Wrap paramiko to make it simpler to use and understand the code from other parts of satori.
- Accept a password string, private key string, or path to private key file for auth. Paramiko will automatically check in the standard places for ssh keys if nothing else is provided.
- Manage authentication mechanisms, retry authenticating, and prefer SSH keys.
- Implement/override a
connect()
method to do this.
- Implement/override a
- Provide a method,
test_connection()
, for doing just that. - Manage connecting and disconnecting when
remote_execute()
is called. (Lazy load the auth object) - Attempt to handle password prompts for non-passwordless sudoers
- Attempt to handle hiccups with pty/tty rules by retrying the command with a pty channel[1] if the system responds with "sudo requires a tty" or similar
- Support ssh proxy connections[2], and create an implementation that provides the same behavior whether connecting through a proxy or connecting to the remote host directly.
- Implement an instance property,
platform_info
, that will return the remote host's platform info using (python >=2.4)'s platform module
For the platform requirements:
- Remote system requires python>=2.4
- architecture, distro, version
- e.g. Ubuntu 12.04 x86_64 would return
-
{'arch': 'x86_64', 'dist': 'ubuntu', 'version': '12.04'}
-
# function signature def connect(host, credentials, port=22, timeout=None, proxy=None): """Connect to remote host over SSH and return a client connection. credentials can have: username (required) password private_key private_key_file proxy can have: host (required if proxy supplied) username (required if proxy supplied) port timeout password private_key private_key_file """
- ↑ 1.0 1.1 paramiko.channel.Channel.get_pty See get_pty().
- ↑ 2.0 2.1 paramiko.client.SSHClient.connect See sock keyword argument.
Notes:
We considered the following to stay within pylint's max 5 argument rule, but we decided to break the rule for practicality...
# Simplest use case from satori import ssh connection = ssh.connect("10.1.1.20", username="root", password="Password", key=None) output = connection.remote_execute("sudo echo hello", with_exit_code=True, timeout=None) >>> {'stdout': 'hello', 'stderr': '', 'exit_code': 0}
# More options from satori import ssh client = ssh.Client("10.1.1.20", port=2222, timeout=1000, StrictHostKeyChecking=True) client.set_credentials(username="root", password="Password") if proxy_ip: proxy = ssh.Client(proxy_ip, port=22) proxy.set_credentials(username=proxy_user, password=proxy_pass) else: proxy = None connection = client.connect(proxy=proxy) output = connection.remote_execute("sudo echo hello", with_exit_code=True, timeout=None) >>> {'stdout': 'hello', 'stderr': '', 'exit_code': 0}