[sunbeam-machine] Add proxy configs

Add http_proxy, https_proxy, no_proxy as
configuration to charm. Update the content
of /etc/environment file on setting the
proxy configs.
If the proxy configuration is not set on
sunbeam-machine, clear the corresponding
configs from /etc/environment.

Change-Id: I5ba444d87e199a4314439eddf513729138c40c3f

charms/sunbeam-machine/config.yaml

@@ -6,4 +6,12 @@ options:
   debug:
     default: False
     type: boolean
-
+  http_proxy:
+    description: Set HTTP_PROXY in /etc/environment
+    type: string
+  https_proxy:
+    description: Set HTTPS_PROXY in /etc/environment
+    type: string
+  no_proxy:
+    description: Set NO_PROXY in /etc/environment
+    type: string

charms/sunbeam-machine/src/charm.py

@@ -33,6 +33,7 @@ from ops.main import (
     main,
 )
 
+ETC_ENVIRONMENT = "/etc/environment"
 logger = logging.getLogger(__name__)
 
 
@@ -41,6 +42,7 @@ class SunbeamMachineCharm(sunbeam_charm.OSBaseOperatorCharm):
 
     _state = ops.framework.StoredState()
     service_name = "sunbeam-machine"
+    proxy_configs = ["http_proxy", "https_proxy", "no_proxy"]
 
     def __init__(self, framework: ops.Framework) -> None:
         super().__init__(framework)
@@ -64,6 +66,34 @@ class SunbeamMachineCharm(sunbeam_charm.OSBaseOperatorCharm):
             logger.error("Error executing sysctl", exc_info=True)
             raise sunbeam_guard.BlockedExceptionError("Sysctl command failed")
 
+    def _on_config_changed(self, event: ops.ConfigChangedEvent):
+        self.configure_charm(event)
+        with open(ETC_ENVIRONMENT, mode="r", encoding="utf-8") as file:
+            current_env = dict(
+                line.strip().split("=", 1) for line in file if "=" in line
+            )
+            logger.info(f"Existing content of /etc/environment: {current_env}")
+
+        proxy = {p: v for p in self.proxy_configs if (v := self.config.get(p))}
+        if all(
+            proxy.get(p) == current_env.get(p.upper())
+            for p in self.proxy_configs
+        ):
+            return
+
+        # Remove proxies not set
+        not_set_proxies = self.proxy_configs - proxy.keys()
+        for p in not_set_proxies:
+            if (p_upper := p.upper()) in current_env:
+                del current_env[p_upper]
+
+        # Capitalise proxy keys and update env
+        proxy_in_caps = {k.upper(): v for k, v in proxy.items()}
+        current_env.update(proxy_in_caps)
+
+        with open(ETC_ENVIRONMENT, mode="w", encoding="utf-8") as file:
+            file.write("\n".join([f"{k}={v}" for k, v in current_env.items()]))
+
     def _on_remove(self, event: ops.RemoveEvent):
         self.sysctl.remove()
 

charms/sunbeam-machine/tests/unit/test_charm.py

@@ -14,6 +14,11 @@
 
 """Tests for Sunbeam Machine charm."""
 
+from unittest.mock import (
+    mock_open,
+    patch,
+)
+
 import charm
 import ops_sunbeam.test_utils as test_utils
 
@@ -30,7 +35,7 @@ class _SunbeamMachineCharm(charm.SunbeamMachineCharm):
 class TestCharm(test_utils.CharmTestCase):
     """Classes for testing Sunbeam Machine charm."""
 
-    PATCHES = []
+    PATCHES = ["sysctl"]
 
     def setUp(self):
         """Setup Sunbeam machine tests."""
@@ -46,5 +51,108 @@ class TestCharm(test_utils.CharmTestCase):
 
     def test_initial(self):
         """Bootstrap test initial."""
-        self.harness.begin_with_initial_hooks()
+        file_content_dict = {"PATH": "FAKEPATH"}
+        env_file_content = "\n".join(
+            f"{k}={v}" for k, v in file_content_dict.items()
+        )
+
+        with patch(
+            "builtins.open", new_callable=mock_open, read_data=env_file_content
+        ) as mock_file:
+            self.harness.begin_with_initial_hooks()
+            mock_file().write.assert_not_called()
+
         self.assertTrue(self.harness.charm.bootstrapped())
+
+    def test_proxy_settings(self):
+        """Test setting proxies."""
+        # test_data is a tuple of /etc/environment file content as dict, proxy config as dict,
+        # expected content as dict
+        # As the below tests are run in loop as subtests, they act as juju config commands.
+        # Means the configs set in the previous test data remains until it is reset by
+        # specifying config as empty string.
+        test_data = [
+            # Case 1: No proxy in environment file, set http_proxy, https_proxy
+            (
+                {"PATH": "FAKEPATH"},
+                {
+                    "http_proxy": "http://proxyserver:3128",
+                    "https_proxy": "http://proxyserver:3128",
+                },
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3128",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                },
+            ),
+            # Case 2: Add no_proxy to above configuration
+            (
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3128",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                },
+                {"no_proxy": "localhost,127.0.0.1"},
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3128",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                    "NO_PROXY": "localhost,127.0.0.1",
+                },
+            ),
+            # Case 3: Update http proxy to different value
+            (
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3128",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                    "NO_PROXY": "localhost,127.0.0.1",
+                },
+                {
+                    "http_proxy": "http://proxyserver:3120",
+                    "https_proxy": "http://proxyserver:3128",
+                },
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3120",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                    "NO_PROXY": "localhost,127.0.0.1",
+                },
+            ),
+            # Case 4: Reset the no_proxy config
+            (
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3120",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                    "NO_PROXY": "localhost,127.0.0.1",
+                },
+                {"no_proxy": ""},
+                {
+                    "PATH": "FAKEPATH",
+                    "HTTP_PROXY": "http://proxyserver:3120",
+                    "HTTPS_PROXY": "http://proxyserver:3128",
+                },
+            ),
+        ]
+
+        with patch(
+            "builtins.open", new_callable=mock_open, read_data=""
+        ) as mock_file:
+            self.harness.begin_with_initial_hooks()
+
+        for index, d in enumerate(test_data):
+            with self.subTest(msg=f"test_proxy_settings-{index}", data=d):
+                env_file_content = "\n".join(
+                    f"{k}={v}" for k, v in d[0].items()
+                )
+                expected_content = "\n".join(
+                    f"{k}={v}" for k, v in d[2].items()
+                )
+                with patch(
+                    "builtins.open",
+                    new_callable=mock_open,
+                    read_data=env_file_content,
+                ) as mock_file:
+                    self.harness.update_config(d[1])
+                    mock_file().write.assert_called_with(expected_content)