Replace hardcoded SSH options with environment variable for secure and flexible rsync configuration

[Copilot]

The CI pipeline was failing during pytest validation with a "Host key verification failed" error when the test_sync_to test attempted to use rsync over SSH. This occurred because the rsync command in the sync_to method creates a separate SSH connection that doesn't inherit the paramiko AutoAddPolicy() setting used by the main SSH connection.

Problem

RuntimeError: rsync failed with code 255:
STDOUT:

STDERR:
Host key verification failed.
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: unexplained error (code 255) at io.c(232) [Receiver=3.2.7]

Solution

Instead of hardcoding SSH options that disable host key verification for all environments, this PR implements a flexible environment variable approach that maintains security by default while allowing CI environments to specify needed options.

The sync_to method now checks for the SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS environment variable and adds any specified SSH options to the rsync command. The CI configuration has been updated to set this environment variable with the necessary options for the validation job.

Implementation

The fix replaces hardcoded options with environment variable support:

# Add extra SSH options from environment variable if set
# This allows CI environments or users to specify additional SSH options
extra_ssh_options = os.environ.get('SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS')
if extra_ssh_options:
    # Split the string into individual options, handling quoted arguments properly
    ssh_parts += shlex.split(extra_ssh_options)

The CI configuration now includes:

validation:
  env:
    SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS: "-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"

Benefits

• Security: Secure by default - no hardcoded insecure options
• Flexibility: CI environments can set required options via environment variable
• Separation of concerns: Library doesn't need to know about CI-specific requirements
• Extensibility: Users can specify any additional SSH options they need

Usage

For CI environments that need to disable host key checking:

export SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"

For other custom SSH configurations:

export SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS="-o ConnectTimeout=10 -o ServerAliveInterval=60"

Impact

• Scope: Only affects the rsync SSH connection in sync_to, not the main paramiko connection
• Security: Maintains security by default while allowing flexibility when needed
• Compatibility: No breaking changes to existing functionality
• CI Integration: Environment variable configured in CI to ensure tests pass

Fixes #2.

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[thorwhalen]

Add this systematically could be a security risk.
Ideally, having a solution implemented in the CI script only would be better. It is not sshdol's concern, so should be separate.

At a minimum, replacing this with:

        # Add SSH options to handle host key verification
        # This is needed for CI environments where host keys may not be in known_hosts
        if os.environ.get('CI') == 'true':
            ssh_parts += ["-o", "StrictHostKeyChecking=no", "-o", "UserKnownHostsFile=/dev/null"]

would be slightly better.

If no solution that is CI-script only can be found, another way to setup the base objects would be to have a special SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS environment variable that would be used (after transforming it's string value to a list of "parts") instead of the hardcoded ["-o", "StrictHostKeyChecking=no", "-o", "UserKnownHostsFile=/dev/null"]. That way, CI would have a place to communicate this need (by setting this env var), and we could pretend we're still doing separation of concerns, since we can also use this mechanism in other situations.

[thorwhalen]

@copilot, can you make these changes?

[Copilot]

I've implemented the environment variable approach as you suggested. The solution replaces the hardcoded SSH options with SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS environment variable for better separation of concerns and security.

The implementation:

• Is secure by default (no hardcoded insecure options)
• Allows CI environments to set the needed options via environment variable
• Provides flexibility for any additional SSH options users might need
• Uses shlex.split() to properly handle quoted arguments

For CI, the environment variable can be set to:
SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"

Commit: b81c7e8

[thorwhalen]

@copilot, go ahead and add the
SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"
in the ci.yml file, in the appropriate place.

[Copilot]

I've added the SSHDOL_SYNC_TO_EXTRA_SSH_OPTIONS environment variable to the CI validation job in the ci.yml file. The environment variable is set to "-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" which will allow the SSH tests to pass in the CI environment by disabling host key verification.

Commit: c19d066