feat(oracle): ability to specify vcn by name for subnet selection

Oracle's pycloudlib implementation currently uses the most recently created VCN (Virtual Cloud Network) in the given compartment for new VM instances being created. Problems can therefore arise if a newly created VCN uses a subnet with different rules than the previously used VCN's subnet.
Now, instead of relying on just blindly choosing the most recently created VCN, pycloudlib supports specifying a vcn_name value which it will use to find a VCN that has a name that exactly matches the given vcn_name.

Author: a-dubs

VERSION

@@ -1 +1 @@
-1!5.1.0
+1!5.2.0

pycloudlib/oci/cloud.py

@@ -33,6 +33,7 @@ def __init__(
         compartment_id: Optional[str] = None,
         config_path: Optional[str] = None,
         config_dict: Optional[str] = None,
+        vcn_name: Optional[str] = None,
     ):
         """
         Initialize the connection to OCI.
@@ -52,6 +53,8 @@ def __init__(
             config_path: Path of OCI config file
             config_dict: A dictionary containing the OCI config.
                 Overrides the values from config_path
+            vcn_name: Exact name of the VCN to use. If not provided, the newest
+                VCN in the given compartment will be used.
         """
         super().__init__(
             tag,
@@ -106,6 +109,8 @@ def __init__(
                 )
             self.oci_config = oci.config.from_file(config_path)  # type: ignore
 
+        self.vcn_name = vcn_name
+
         self._log.debug("Logging into OCI")
         self.compute_client = oci.core.ComputeClient(self.oci_config)  # type: ignore # noqa: E501
         self.network_client = oci.core.VirtualNetworkClient(self.oci_config)  # type: ignore # noqa: E501
@@ -245,6 +250,8 @@ def launch(
             retry_strategy: a retry strategy from oci.retry module
                 to apply for this operation
             username: username to use when connecting via SSH
+            vcn_name: Name of the VCN to use. If not provided, the first VCN
+                found will be used
             **kwargs: dictionary of other arguments to pass as
                 LaunchInstanceDetails
 
@@ -258,7 +265,10 @@ def launch(
                 f" Found: {image_id}"
             )
         subnet_id = get_subnet_id(
-            self.network_client, self.compartment_id, self.availability_domain
+            self.network_client,
+            self.compartment_id,
+            self.availability_domain,
+            vcn_name=self.vcn_name,
         )
         metadata = {
             "ssh_authorized_keys": self.key_pair.public_key_content,

pycloudlib/oci/utils.py

@@ -1,7 +1,7 @@
 # This file is part of pycloudlib. See LICENSE file for license information.
 """Utilities for OCI images and instances."""
 import time
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from pycloudlib.errors import PycloudlibError
 
@@ -37,6 +37,7 @@ def get_subnet_id(
     network_client: "oci.core.VirtualNetworkClient",  # type: ignore
     compartment_id: str,
     availability_domain: str,
+    vcn_name: Optional[str] = None,
 ) -> str:
     """Get a subnet id linked to `availability_domain`.
 
@@ -47,13 +48,26 @@ def get_subnet_id(
         network_client: Instance of VirtualNetworkClient.
         compartment_id: Compartment where the subnet has to belong
         availability_domain: Domain to look for subnet id in.
+        vcn_name: Exact name of the VCN to use. If not provided, the newest
+            VCN in the given compartment will be used.
     Returns:
-        The updated version of the current_data
+        id of the subnet selected
     Raises:
         `Exception` if unable to determine `subnet_id` for
         `availability_domain`
     """
-    vcn_id = network_client.list_vcns(compartment_id).data[0].id
+    if vcn_name is not None:  # if vcn_name specified, use that vcn
+        vcns = network_client.list_vcns(
+            compartment_id, display_name=vcn_name
+        ).data
+        if len(vcns) == 0:
+            raise PycloudlibError(f"Unable to determine vcn name: {vcn_name}")
+        if len(vcns) > 1:
+            raise PycloudlibError(f"Found multiple vcns with name: {vcn_name}")
+        vcn_id = vcns[0].id
+    else:  # if no vcn_name specified, use most recently created vcn
+        vcn_id = network_client.list_vcns(compartment_id).data[0].id
+
     subnets = network_client.list_subnets(compartment_id, vcn_id=vcn_id).data
     subnet_id = None
     for subnet in subnets: