initial code towards services that will generate files from templates and provide configuration

daemon/core/configservice/base.py

@@ -0,0 +1,128 @@
+import abc
+import enum
+import inspect
+import logging
+import pathlib
+import time
+from typing import Any, Dict, List
+
+from mako import exceptions
+from mako.lookup import TemplateLookup
+
+from core.errors import CoreCommandError, CoreError
+from core.nodes.base import CoreNode
+
+TEMPLATES_DIR = "templates"
+
+
+class ConfigServiceMode(enum.Enum):
+    BLOCKING = 0
+    NON_BLOCKING = 1
+    TIMER = 2
+
+
+class ConfigService(abc.ABC):
+    # validation period in seconds, how frequent validation is attempted
+    validation_period = 0.5
+
+    # time to wait in seconds for determining if service started successfully
+    validation_timer = 5
+
+    def __init__(self, node: CoreNode) -> None:
+        self.node = node
+        class_file = inspect.getfile(self.__class__)
+        templates_path = pathlib.Path(class_file).parent.joinpath(TEMPLATES_DIR)
+        logging.info(templates_path)
+        self.templates = TemplateLookup(directories=templates_path)
+
+    @property
+    @abc.abstractmethod
+    def name(self):
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def group(self):
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def executables(self) -> List[str]:
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def dependencies(self) -> List[str]:
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def startup(self) -> List[str]:
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def validate(self) -> List[str]:
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def shutdown(self) -> List[str]:
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def validation_mode(self) -> ConfigServiceMode:
+        raise NotImplementedError
+
+    def start(self) -> None:
+        if not self.startup:
+            return
+        wait = self.validation_mode == ConfigServiceMode.BLOCKING
+        start = time.monotonic()
+        index = 0
+        cmds = self.startup[:]
+        while cmds:
+            cmd = cmds[index]
+            try:
+                self.node.cmd(cmd, wait=wait)
+                del cmds[index]
+                index += 1
+            except CoreCommandError:
+                logging.exception("error starting command")
+                time.sleep(self.validation_period)
+
+            if time.monotonic() - start > 0:
+                raise CoreError(
+                    f"node({self.node.name}) service({self.name()}) failed to start"
+                )
+
+    def stop(self) -> None:
+        if not self.shutdown:
+            return
+        for cmd in self.shutdown:
+            self.node.cmd(cmd, wait=False)
+
+    def restart(self):
+        self.stop()
+        self.start()
+
+    def run(self, cmd: str, wait: bool = True):
+        self.node.cmd(cmd, wait)
+
+    def create_files(self) -> None:
+        raise NotImplementedError
+
+    def render(self, name: str, data: Dict[str, Any] = None) -> None:
+        if data is None:
+            data = {}
+        try:
+            template = self.templates.get_template(name)
+            rendered = template.render_unicode(node=self.node, **data)
+            print(rendered)
+            # self.node.nodefile(name, rendered)
+        except Exception:
+            raise CoreError(
+                f"error rendering template: {name}"
+                f"{exceptions.text_error_template().render()}"
+            )