go-framework init and extension

charmcraft/application/commands/init.py

@@ -38,6 +38,7 @@
     "machine": "init-machine",
     "flask-framework": "init-flask-framework",
     "django-framework": "init-django-framework",
+    "go-framework": "init-go-framework",
 }
 DEFAULT_PROFILE = "simple"
 

charmcraft/extensions/__init__.py

@@ -18,7 +18,7 @@
 
 from charmcraft.extensions._utils import apply_extensions
 from charmcraft.extensions.extension import Extension
-from charmcraft.extensions.gunicorn import DjangoFramework, FlaskFramework
+from charmcraft.extensions.twelvefactor import DjangoFramework, FlaskFramework, GoFramework
 from charmcraft.extensions.registry import (
     get_extension_class,
     get_extension_names,
@@ -41,3 +41,4 @@
 
 register("flask-framework", FlaskFramework)
 register("django-framework", DjangoFramework)
+register("go-framework", GoFramework)

charmcraft/extensions/gunicorn.py → charmcraft/extensions/twelvefactor.py

@@ -24,27 +24,8 @@
 from .extension import Extension
 
 
-class _GunicornBase(Extension):
-    """A base class for 12-factor WSGI applications."""
-
-    _WEBSERVER_OPTIONS = {
-        "webserver-keepalive": {
-            "type": "int",
-            "description": "Time in seconds for webserver to wait for requests on a Keep-Alive connection.",
-        },
-        "webserver-threads": {
-            "type": "int",
-            "description": "Run each webserver worker with the specified number of threads.",
-        },
-        "webserver-timeout": {
-            "type": "int",
-            "description": "Time in seconds to kill and restart silent webserver workers.",
-        },
-        "webserver-workers": {
-            "type": "int",
-            "description": "The number of webserver worker processes for handling requests.",
-        },
-    }
+class _TwelveFactorBase(Extension):
+    """A base class for 12-factor applications."""
 
     _CHARM_LIBS = [
         {"lib": "traefik_k8s.ingress", "version": "2"},
@@ -138,10 +119,10 @@ def _get_root_snippet(self) -> dict[str, Any]:
         return {
             "assumes": ["k8s-api"],
             "containers": {
-                f"{self.framework}-app": {"resource": f"{self.framework}-app-image"},
+                self.get_container_name(): {"resource": self.get_image_name()},
             },
             "resources": {
-                f"{self.framework}-app-image": {
+                self.get_image_name(): {
                     "type": "oci-image",
                     "description": f"{self.framework} application image.",
                 },
@@ -157,7 +138,7 @@ def _get_root_snippet(self) -> dict[str, Any]:
                 "metrics-endpoint": {"interface": "prometheus_scrape"},
                 "grafana-dashboard": {"interface": "grafana_dashboard"},
             },
-            "config": {"options": {**self._WEBSERVER_OPTIONS, **self.options}},
+            "config": {"options": self.options},
             "parts": {
                 "charm": {
                     "plugin": "charm",
@@ -184,8 +165,36 @@ def get_parts_snippet(self) -> dict[str, Any]:
         """Return the parts to add to parts."""
         return {}
 
+    def get_container_name(self) -> str:
+        """Return name of the container for the app image."""
+        return f"{self.framework}-app"
+
+    def get_image_name(self) -> str:
+        """Return name of the app image."""
+        return f"{self.framework}-app-image"
+
+
+GUNICORN_WEBSERVER_OPTIONS = {
+    "webserver-keepalive": {
+        "type": "int",
+        "description": "Time in seconds for webserver to wait for requests on a Keep-Alive connection.",
+    },
+    "webserver-threads": {
+        "type": "int",
+        "description": "Run each webserver worker with the specified number of threads.",
+    },
+    "webserver-timeout": {
+        "type": "int",
+        "description": "Time in seconds to kill and restart silent webserver workers.",
+    },
+    "webserver-workers": {
+        "type": "int",
+        "description": "The number of webserver worker processes for handling requests.",
+    },
+}
+
 
-class FlaskFramework(_GunicornBase):
+class FlaskFramework(_TwelveFactorBase):
     """Extension for 12-factor Flask applications."""
 
     framework = "flask"
@@ -195,6 +204,7 @@ class FlaskFramework(_GunicornBase):
         }
     }
     options = {
+        **GUNICORN_WEBSERVER_OPTIONS,
         "flask-application-root": {
             "type": "string",
             "description": "Path in which the application / web server is mounted. This configuration will set the FLASK_APPLICATION_ROOT environment variable. Run `app.config.from_prefixed_env()` in your Flask application in order to receive this configuration.",
@@ -233,7 +243,7 @@ def is_experimental(base: tuple[str, ...] | None) -> bool:  # noqa: ARG004
         return False
 
 
-class DjangoFramework(_GunicornBase):
+class DjangoFramework(_TwelveFactorBase):
     """Extension for 12-factor Django applications."""
 
     framework = "django"
@@ -248,6 +258,7 @@ class DjangoFramework(_GunicornBase):
         },
     }
     options = {
+        **GUNICORN_WEBSERVER_OPTIONS,
         "django-debug": {
             "type": "boolean",
             "default": False,
@@ -262,3 +273,45 @@ class DjangoFramework(_GunicornBase):
             "description": "A comma-separated list of host/domain names that this Django site can serve. This configuration will set the DJANGO_ALLOWED_HOSTS environment variable with its content being a JSON encoded list.",
         },
     }
+
+
+class GoFramework(_TwelveFactorBase):
+    """Extension for 12-factor Go applications."""
+
+    framework = "go"
+    actions = {
+        "rotate-secret-key": {
+            "description": "Rotate the go secret key. Users will be forced to log in again. This might be useful if a security breach occurs."
+        }
+    }
+    options = {
+        "port": {
+            "type": "int",
+            "default": 8080,
+            "description": "Default port where the application will listen on.",
+        },
+        "metrics-port": {
+            "type": "int",
+            "default": 8080,
+            "description": "Port where the prometheus metrics will be scraped.",
+        },
+        "metrics-path": {
+            "type": "string",
+            "default": "/metrics",
+            "description": "Path where the prometheus metrics will be scraped.",
+        },
+        "secret-key": {
+            "type": "string",
+            "description": "Long secret you can use for sessions, csrf or any other thing where you need a random secret shared by all units",
+        },
+    }
+
+    @override
+    def get_image_name(self) -> str:
+        """Return name of the app image."""
+        return "app-image"
+
+    @override
+    def get_container_name(self) -> str:
+        """Return name of the container for the app image."""
+        return "app"

charmcraft/templates/init-go-framework/.gitignore.j2

@@ -0,0 +1,9 @@
+venv/
+build/
+*.charm
+.tox/
+.coverage
+__pycache__/
+*.py[cod]
+.idea
+.vscode/

charmcraft/templates/init-go-framework/charmcraft.yaml.j2

@@ -0,0 +1,53 @@
+# This file configures Charmcraft.
+# See https://juju.is/docs/sdk/charmcraft-config for guidance.
+
+name: {{ name }}
+
+type: charm
+
+bases:
+  - build-on:
+    - name: ubuntu
+      channel: "22.04"
+    run-on:
+    - name: ubuntu
+      channel: "22.04"
+
+# (Required)
+summary: A very short one-line summary of the Go application.
+
+# (Required)
+description: |
+  A comprehensive overview of your Go application.
+
+extensions:
+  - go-framework
+
+# Uncomment the integrations used by your application
+# Integrations set to "optional: false" will block the charm
+# until the applications are integrated.
+# requires:
+#   mysql:
+#     interface: mysql_client
+#     optional: false
+#     limit: 1
+#   postgresql:
+#     interface: postgresql_client
+#     optional: false
+#     limit: 1
+#   mongodb:
+#     interface: mongodb_client
+#     optional: false
+#     limit: 1
+#   redis:
+#     interface: redis
+#     optional: false
+#     limit: 1
+#   s3:
+#     interface: s3
+#     optional: false
+#     limit: 1
+#   saml:
+#     interface: saml
+#     optional: false
+#     limit: 1

charmcraft/templates/init-go-framework/requirements.txt.j2

@@ -0,0 +1 @@
+paas-app-charmer==1.*

charmcraft/templates/init-go-framework/src/charm.py.j2

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+# Copyright {{ year }} {{ author }}
+# See LICENSE file for licensing details.
+
+"""Go Charm entrypoint."""
+
+import logging
+import typing
+
+import ops
+
+import paas_app_charmer.go
+
+logger = logging.getLogger(__name__)
+
+
+class GoCharm(paas_app_charmer.go.Charm):
+    """Go Charm service."""
+
+    def __init__(self, *args: typing.Any) -> None:
+        """Initialize the instance.
+
+        Args:
+            args: passthrough to CharmBase.
+        """
+        super().__init__(*args)
+
+
+if __name__ == "__main__":
+    ops.main.main(GoCharm)

tests/extensions/test_gunicorn.py → tests/extensions/test_twelvefactor.py

@@ -17,7 +17,7 @@
 
 from charmcraft.errors import ExtensionError
 from charmcraft.extensions import apply_extensions
-from charmcraft.extensions.gunicorn import DjangoFramework, FlaskFramework
+from charmcraft.extensions.twelvefactor import DjangoFramework, FlaskFramework, GoFramework
 
 
 def make_flask_input_yaml():
@@ -63,7 +63,7 @@ def flask_input_yaml_fixture():
                     {"lib": "saml_integrator.saml", "version": "0"},
                 ],
                 "config": {
-                    "options": {**FlaskFramework.options, **FlaskFramework._WEBSERVER_OPTIONS}
+                    "options": {**FlaskFramework.options},
                 },
                 "parts": {
                     "charm": {
@@ -123,7 +123,7 @@ def flask_input_yaml_fixture():
                     {"lib": "saml_integrator.saml", "version": "0"},
                 ],
                 "config": {
-                    "options": {**DjangoFramework.options, **DjangoFramework._WEBSERVER_OPTIONS}
+                    "options": {**DjangoFramework.options},
                 },
                 "parts": {
                     "charm": {
@@ -152,6 +152,66 @@ def flask_input_yaml_fixture():
                 "type": "charm",
             },
         ),
+        (
+            {
+                "type": "charm",
+                "name": "test-go",
+                "summary": "test summary",
+                "description": "test description",
+                "bases": [{"name": "ubuntu", "channel": "22.04"}],
+                "extensions": ["go-framework"],
+            },
+            True,
+            {
+                "actions": GoFramework.actions,
+                "assumes": ["k8s-api"],
+                "bases": [{"channel": "22.04", "name": "ubuntu"}],
+                "containers": {
+                    "app": {"resource": "app-image"},
+                },
+                "description": "test description",
+                "name": "test-go",
+                "charm-libs": [
+                    {"lib": "traefik_k8s.ingress", "version": "2"},
+                    {"lib": "observability_libs.juju_topology", "version": "0"},
+                    {"lib": "grafana_k8s.grafana_dashboard", "version": "0"},
+                    {"lib": "loki_k8s.loki_push_api", "version": "0"},
+                    {"lib": "data_platform_libs.data_interfaces", "version": "0"},
+                    {"lib": "prometheus_k8s.prometheus_scrape", "version": "0"},
+                    {"lib": "redis_k8s.redis", "version": "0"},
+                    {"lib": "data_platform_libs.s3", "version": "0"},
+                    {"lib": "saml_integrator.saml", "version": "0"},
+                ],
+                "config": {
+                    "options": {**GoFramework.options},
+                },
+                "parts": {
+                    "charm": {
+                        "plugin": "charm",
+                        "source": ".",
+                        "build-snaps": ["rustup"],
+                        "override-build": "rustup default stable\ncraftctl default",
+                    }
+                },
+                "peers": {"secret-storage": {"interface": "secret-storage"}},
+                "provides": {
+                    "metrics-endpoint": {"interface": "prometheus_scrape"},
+                    "grafana-dashboard": {"interface": "grafana_dashboard"},
+                },
+                "requires": {
+                    "logging": {"interface": "loki_push_api"},
+                    "ingress": {"interface": "ingress", "limit": 1},
+                },
+                "resources": {
+                    "app-image": {
+                        "description": "go application image.",
+                        "type": "oci-image",
+                    },
+                },
+                "summary": "test summary",
+                "type": "charm",
+            },
+        ),
     ],
 )
 def test_apply_extensions_correct(monkeypatch, experimental, tmp_path, input_yaml, expected):
@@ -184,7 +244,6 @@ def test_flask_merge_options(flask_input_yaml, tmp_path):
     assert applied["config"] == {
         "options": {
             **FlaskFramework.options,
-            **FlaskFramework._WEBSERVER_OPTIONS,
             **added_options,
         }
     }