Ansible Pylibssh

Common errors

• [WARNING]: ansible-pylibssh not installed, falling back to paramiko

  cause Ansible defaults to using the 'paramiko' SSH library because 'ansible-pylibssh' is not installed.
  fix Install 'ansible-pylibssh' using pip: 'pip install ansible-pylibssh'.

• fatal: [10.96.192.10]: FAILED! => {"changed": false, "msg": "paramiko: The authenticity of host '10.96.192.10' can't be established.\nThe ssh-ed25519 key fingerprint is b'REDACTED'."}

  cause The SSH client cannot verify the host's identity because the host key is not in the known_hosts file.
  fix Manually add the host key to the known_hosts file or configure Ansible to accept unknown host keys.

• ld: library not found for -lssh

  cause The linker cannot find the 'libssh' library during the installation of 'ansible-pylibssh'.
  fix Ensure 'libssh' is installed on your system. On macOS, you can install it using Homebrew: 'brew install libssh'.

• fatal: [10.2.201.194]: FAILED! => {"changed": false, "msg": "paramiko is not installed: No module named 'paramiko'"}

  cause Ansible falls back to 'paramiko' for SSH connections, but 'paramiko' is not installed.
  fix Install 'paramiko' using pip: 'pip install paramiko'.

• fatal error: 'libssh/libssh.h' file not found

  cause ansible-pylibssh requires the `libssh` client library and its development headers (version 0.9.0 or newer) to be present and discoverable by the compiler during installation, which can be challenging on macOS or when building from source without proper CFLAGS.
  fix Install `libssh` using your system's package manager (e.g., `brew install libssh` on macOS, `sudo apt-get install libssh-dev` on Debian/Ubuntu, `sudo dnf install libssh-devel` on RHEL/Fedora) and then install `ansible-pylibssh` using `pip` with appropriate CFLAGS if necessary, especially on macOS. For macOS with Homebrew, use: `CFLAGS="-I $(brew --prefix)/include -I ext -L $(brew --prefix)/lib -lssh" pip install ansible-pylibssh`

Warnings

• gotcha The library is a set of Python bindings for `libssh`. Therefore, `libssh` (version 0.9.0 or newer) must be installed at the system level for `ansible-pylibssh` to function. Installing the Python package via pip alone is insufficient.
  Fix: Install `libssh` development packages (e.g., `libssh-dev` on Debian/Ubuntu, `libssh-devel` on RHEL/Fedora, or via Homebrew on macOS) matching version 0.9.0 or later on your operating system.
• breaking Support for Python 3.6, 3.7, and 3.8 was dropped with version 1.4.0. Installations on these Python versions will fail or result in an incompatible state.
  Fix: Upgrade your Python environment to Python 3.9 or newer before installing `ansible-pylibssh` version 1.4.0 or later.
• gotcha Older versions (prior to v1.2.2) had a bug where downloading files larger than 64kB over SCP could fail, leading to incomplete transfers.
  Fix: Upgrade `ansible-pylibssh` to version 1.2.2 or newer to ensure reliable SCP transfers for larger files.
• gotcha Prior to version 1.2.1, attempting to download a non-existent remote file via SCP could lead to program crashes.
  Fix: Upgrade `ansible-pylibssh` to version 1.2.1 or newer to prevent crashes when handling non-existent remote files during SCP operations.
• gotcha Earlier versions (prior to v1.2.0) could crash if `channel.recv` was called and `libssh` returned an `SSH_EOF` error, or if a channel was not explicitly closed.
  Fix: Upgrade `ansible-pylibssh` to version 1.2.0 or newer for improved stability and crash prevention related to channel handling.
• breaking As of version 1.4.0, macOS wheels require macOS version 15.0 or newer due to updates in the `cibuildwheel` process. Installations on older macOS versions may encounter issues.
  Fix: Ensure your macOS environment is version 15.0 or newer when installing `ansible-pylibssh` 1.4.0+ to use pre-compiled wheels. Alternatively, attempt to build from source (which may require specific build tools and `libssh` installation).

Install

• pip install ansible-pylibssh Install stable version

Imports

• Session
  wrong:

  from ansible_pylibssh.session import Session

  correct:

  from pylibsshext.session import Session

  Core classes are exposed via the `pylibsshext` module, not directly from `ansible_pylibssh`.
• LibsshSessionException
  wrong:

  from ansible_pylibssh.errors import LibsshSessionException

  correct:

  from pylibsshext.errors import LibsshSessionException

  Exceptions are located in the `pylibsshext.errors` submodule.
• __version__

  from pylibsshext import __version__

  Library version information and other global attributes are available directly from `pylibsshext`.

Quickstart

This quickstart demonstrates how to establish an SSH session, execute a simple command, and then properly disconnect. It uses environment variables for host, user, and password for security and flexibility. Ensure the `libssh` C library is installed on your system and replace `SSH_HOST` and `SSH_USER` with valid credentials if not using a passwordless setup.

import os
from pylibsshext.errors import LibsshSessionException
from pylibsshext.session import Session

HOST = os.environ.get('SSH_HOST', 'localhost')
USER = os.environ.get('SSH_USER', 'testuser')
PASSWORD = os.environ.get('SSH_PASSWORD', '')
# Use a placeholder if not set, but real connections need a password or key

if not PASSWORD:
    print("Warning: SSH_PASSWORD environment variable not set. Connection might fail if password authentication is required.")

TIMEOUT = 30
PORT = 22

ssh = Session()
try:
    ssh.connect(
        host=HOST,
        user=USER,
        password=PASSWORD,
        timeout=TIMEOUT,
        port=PORT,
    )
    print(f'Successfully connected to {HOST}:{PORT}.')
    # Example: Execute a command
    channel = ssh.open_session()
    channel.request_exec('echo Hello from pylibssh!')
    output = channel.read_stdout(2048).decode()
    print(f'Command output: {output.strip()}')
    channel.close()
    channel.send_eof()

except LibsshSessionException as ssh_exc:
    print(f'Failed to connect to {HOST}:{PORT} over SSH: {ssh_exc!s}')
except Exception as e:
    print(f'An unexpected error occurred: {e}')
finally:
    if ssh.is_connected:
        ssh.disconnect()
        print(f'Disconnected from {HOST}.')