MCOL-5496: Merge CMAPI code to engine repo.

[add] cmapi code to engine

cmapi/cmapi_server/process_dispatchers/base.py

@@ -0,0 +1,146 @@
+"""Module contains base process dispatcher class implementation.
+
+Formally this is must have interface for subclasses.
+"""
+
+import logging
+import os
+import shlex
+import subprocess
+from datetime import datetime
+from pathlib import Path
+from typing import Dict, Optional, TextIO, Tuple
+
+from cmapi_server.constants import MCS_INSTALL_BIN, MCS_LOG_PATH
+
+
+class BaseDispatcher:
+    """Class with base interfaces for dispatchers."""
+
+    @staticmethod
+    def _create_mcs_process_logfile(filename: str) -> str:
+        """Create log file by name.
+
+        :param filename: log filename
+        :type filename: str
+        :return: full path of created log file
+        :rtype: str
+        """
+        log_fullpath = os.path.join(MCS_LOG_PATH, filename)
+        Path(log_fullpath).touch(mode=666)
+        return log_fullpath
+
+    @staticmethod
+    def exec_command(
+        command: str, daemonize: bool = False, silent: bool = False,
+        stdout: TextIO = subprocess.PIPE, env: Optional[Dict] = None
+    ) -> Tuple[bool, str]:
+        """Run command using subprocess.
+
+        :param command: command to run
+        :type command: str
+        :param daemonize: run command in detached mode, defaults to False
+        :type daemonize: bool, optional
+        :param silent: prevent error logs on non-zero exit status,
+                       defaults to False
+        :type silent: bool, optional
+        :param stdout: stdout argument for Popen, defaults to subprocess.STDOUT
+        :type stdout: TextIO, optional
+        :param env: environment argument for Popen, defaults to None
+        :type env: Optional[Dict], optional
+        :return: tuple with success status and output string from subprocess,
+                 if there are multiple lines in output they should be splitted
+        :rtype: Tuple[bool, str]
+        """
+        output: str = ''
+        result: Tuple = (False, output)
+        try:
+            proc = subprocess.Popen(
+                shlex.split(command),
+                stdout=stdout,
+                stderr=subprocess.STDOUT,
+                start_new_session=daemonize,
+                env=env,
+                encoding='utf-8'
+            )
+        except Exception:
+            logging.error(f'Failed on run command "{command}".', exc_info=True)
+            # TODO: cmapi have to close with exception here
+            #       to stop docker container?
+            # raise
+            return result
+        if daemonize:
+            # remove Popen object. optionally gc.collect could be invoked.
+            # this is made to prevent eventually spawning duplicated "defunct"
+            # (zombie) python parented processes. This could happened
+            # previously after cluster restart. It didn't affects cluster
+            # condition, only makes "mcs cluster status" command output
+            # confusing and ugly.
+            del proc
+            result = (True, output)
+        else:
+            logging.debug('Waiting command to finish.')
+            stdout_str, _ = proc.communicate()
+            returncode = proc.wait()
+            if stdout_str is not None:
+                # output guaranteed to be empty string not None
+                output = stdout_str
+            result = (True, output)
+            if returncode != 0:
+                if not silent:
+                    logging.error(
+                        f'Calling "{command}" finished with return code: '
+                        f'"{returncode}" and stderr+stdout "{output}".'
+                    )
+                result = (False, output)
+        return result
+
+    @classmethod
+    def _run_dbbuilder(cls, use_su=False) -> None:
+        # attempt to run dbbuilder on primary node
+        # e.g., s3 was setup after columnstore install
+        logging.info('Attempt to run dbbuilder on primary node')
+        dbbuilder_path = os.path.join(MCS_INSTALL_BIN, 'dbbuilder')
+        dbbuilder_arg = '7'
+        dbb_command = f'{dbbuilder_path} {dbbuilder_arg}'
+        if use_su:
+            # TODO: move mysql user to constants
+            dbb_command = f'su -s /bin/sh -c "{dbb_command}" mysql'
+        dbb_log_path = cls._create_mcs_process_logfile('dbbuilder.log')
+        with open(dbb_log_path, 'a', encoding='utf-8') as dbb_log_fh:
+            dbb_start_time = datetime.now().strftime('%d/%b/%Y %H:%M:%S')
+            dbb_log_fh.write(f'-----Started at {dbb_start_time}.-----\n')
+            # TODO: error handling?
+            #       check if exist for next releases?
+            success, _ = cls.exec_command(dbb_command, stdout=dbb_log_fh)
+            dbb_log_fh.write('-----Finished run.-----\n\n')
+
+    @classmethod
+    def init(cls):
+        """Method for dispatcher initialisation."""
+        pass
+
+    @classmethod
+    def is_service_running(cls, service: str, use_sudo: bool) -> bool:
+        """Check if systemd proceess/service is running."""
+        raise NotImplementedError
+
+    @classmethod
+    def start(cls, service: str, is_primary: bool, use_sudo: bool) -> bool:
+        """Start process/service."""
+        raise NotImplementedError
+
+    @classmethod
+    def stop(cls, service: str, is_primary: bool, use_sudo: bool) -> bool:
+        """Stop process/service."""
+        raise NotImplementedError
+
+    @classmethod
+    def restart(cls, service: str, is_primary: bool, use_sudo: bool) -> bool:
+        """Restart process/service."""
+        raise NotImplementedError
+
+    @classmethod
+    def reload(cls, service: str, is_primary: bool, use_sudo: bool) -> bool:
+        """Reload process/service."""
+        raise NotImplementedError