Ensure system_cfg read before ds net config on Oracle (SC-720) (#1174)

In 2c52e6e88b19f5db8d55eb7280ee27703e05d75f, the order of
reading network config was changed for Oracle due to initramfs
needing to take lower precedence than the datasource. However,
this also bumped system_cfg to a lower precedence than ds, which
means that any network configuration specified in /etc/cloud will not
be applied. system_cfg should instead be moved above ds so network
configuration in /etc/cloud takes precedence.

LP: #1956788

2 files changed, 32 insertions, 3 deletions

diff --git a/tests/integration_tests/network/test_net_config_load.py b/tests/integration_tests/network/test_net_config_load.py
new file mode 100644
index 00000000..a6863b63
--- /dev/null
+++ b/tests/integration_tests/network/test_net_config_load.py
@@ -0,0 +1,27 @@
+"""Test loading the network config"""
+import pytest
+
+from tests.integration_tests.instances import IntegrationInstance
+
+
+def _customize_envionment(client: IntegrationInstance):
+    # Insert our "disable_network_config" file here
+    client.write_to_file(
+        "/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg",
+        "network: {config: disabled}\n",
+    )
+    client.execute("cloud-init clean --logs")
+    client.restart()
+
+
+def test_network_disabled_via_etc_cloud(client: IntegrationInstance):
+    """Test that network can be disabled via config file in /etc/cloud"""
+    if client.settings.CLOUD_INIT_SOURCE == "IN_PLACE":
+        pytest.skip(
+            "IN_PLACE not supported as we mount /etc/cloud contents into the "
+            "container"
+        )
+    _customize_envionment(client)
+
+    log = client.read_from_file("/var/log/cloud-init.log")
+    assert "network config is disabled by system_cfg" in log
diff --git a/tests/unittests/sources/test_oracle.py b/tests/unittests/sources/test_oracle.py
index 356b3738..b3e6f10c 100644
--- a/tests/unittests/sources/test_oracle.py
+++ b/tests/unittests/sources/test_oracle.py
@@ -920,12 +920,14 @@ class TestNetworkConfig:
         assert network_config == m_read_initramfs_config.return_value
         assert "Failed to parse secondary network configuration" in caplog.text
 
-    def test_ds_network_cfg_preferred_over_initramfs(self, _m):
-        """Ensure that DS net config is preferred over initramfs config"""
+    def test_ds_network_cfg_order(self, _m):
+        """Ensure that DS net config is preferred over initramfs config
+        but less than system config."""
         config_sources = oracle.DataSourceOracle.network_config_sources
+        system_idx = config_sources.index(NetworkConfigSource.system_cfg)
         ds_idx = config_sources.index(NetworkConfigSource.ds)
         initramfs_idx = config_sources.index(NetworkConfigSource.initramfs)
-        assert ds_idx < initramfs_idx
+        assert system_idx < ds_idx < initramfs_idx
 
 
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