Add ssh opening functions and test.

lolafect/connections.py

@@ -94,6 +94,91 @@ def _temp_secret_file_from_s3(
         os.remove(local_temp_file_path)
 
 
+@task()
+def open_ssh_tunnel_with_s3_pkey(
+    s3_bucket_name: str,
+    ssh_tunnel_credentials: dict,
+    remote_target_host: str,
+    remote_target_port: int,
+) -> SSHTunnelForwarder:
+    """
+    Temporarily fetch a ssh key from S3 and then proceed to open a SSH tunnel
+    using it.
+
+    :param s3_bucket_name: the bucket where the file lives.
+    :param ssh_tunnel_credentials: the details of the jumpthost SSH
+    connection.
+    :param remote_target_host: the remote host to tunnel to.
+    :param remote_target_port: the remote port to tunnel to.
+    :return: the tunnel, already open.
+    """
+    logger = prefect.context.get("logger")
+    logger.info("Going to open an SSH tunnel.")
+
+    temp_file_path = "temp"
+    local_bind_host = "127.0.0.1"
+    local_bind_port = 12345
+
+    with _temp_secret_file_from_s3(
+        s3_bucket_name=s3_bucket_name,
+        s3_file_key=ssh_tunnel_credentials["path_to_ssh_pkey"],
+        local_temp_file_path=temp_file_path,
+    ) as ssh_key_file:
+        tunnel = open_ssh_tunnel(
+            local_bind_host,
+            local_bind_port,
+            remote_target_host,
+            remote_target_port,
+            ssh_key_file,
+            ssh_tunnel_credentials,
+        )
+    logger.info(
+        f"SSH tunnel is now open and listening at {local_bind_host}:{local_bind_port}.\n"
+        f"Tunnel forwards to {remote_target_host}:{remote_target_port}"
+    )
+
+    return tunnel
+
+
+def open_ssh_tunnel(
+    local_bind_host: str,
+    local_bind_port: int,
+    remote_target_host: str,
+    remote_target_port: int,
+    ssh_key_file_path: str,
+    ssh_tunnel_credentials: dict,
+) -> SSHTunnelForwarder:
+    """
+    Configure and start an SSH tunnel.
+
+    :param local_bind_host: the local host address to bind the tunnel to.
+    :param local_bind_port: the local port address to bind the tunnel to.
+    :param remote_target_host: the remote host to forward to.
+    :param remote_target_port: the remote port to forward to.
+    :param ssh_key_file_path: the path to the ssh key.
+    :param ssh_tunnel_credentials: the details of the jumpthost SSH
+    connection.
+    :return: the tunnel, already open.
+    """
+
+    tunnel = SSHTunnelForwarder(
+        ssh_host=(
+            ssh_tunnel_credentials["ssh_jumphost"],
+            ssh_tunnel_credentials["ssh_port"],
+        ),
+        ssh_username=ssh_tunnel_credentials["ssh_username"],
+        ssh_pkey=ssh_key_file_path,
+        remote_bind_address=(
+            remote_target_host,
+            remote_target_port,
+        ),
+        local_bind_address=(local_bind_host, local_bind_port),
+        ssh_private_key_password=ssh_tunnel_credentials["ssh_pkey_password"],
+    )
+    tunnel.start()
+    return tunnel
+
+
 @task(nout=2)
 def connect_to_mysql(
     mysql_credentials: dict,

tests/test_integration/test_connections.py

@@ -1,7 +1,12 @@
 import pathlib
 
 from lolafect.lolaconfig import build_lolaconfig
-from lolafect.connections import connect_to_trino, close_trino_connection, _temp_secret_file_from_s3
+from lolafect.connections import (
+    connect_to_trino,
+    close_trino_connection,
+    _temp_secret_file_from_s3,
+    open_ssh_tunnel_with_s3_pkey,
+)
 
 # __          __     _____  _   _ _____ _   _  _____ _
 # \ \        / /\   |  __ \| \ | |_   _| \ | |/ ____| |
@@ -72,3 +77,18 @@ def test_temporal_download_of_secret_file_works_properly_even_with_exception():
         temp_file_found_when_in_context_manager
         and temp_file_missing_when_outside_context_manager
     )
+
+
+def test_opening_and_closing_ssh_tunnel_works_properly():
+    tunnel = open_ssh_tunnel_with_s3_pkey.run(
+        s3_bucket_name=TEST_LOLACONFIG.S3_BUCKET_NAME,
+        ssh_tunnel_credentials=TEST_LOLACONFIG.SSH_TUNNEL_CREDENTIALS,
+        remote_target_host=TEST_LOLACONFIG.DW_CREDENTIALS["host"],
+        remote_target_port=TEST_LOLACONFIG.DW_CREDENTIALS["port"],
+    )
+    tunnel_was_active = tunnel.is_active
+    tunnel.close()
+
+    tunnel_is_no_longer_active = not tunnel.is_active
+
+    assert tunnel_was_active and tunnel_is_no_longer_active