# sample.py

#

Sample user-defined service.

    from core.service import CoreService
    from core.service import ServiceMode

#

# Custom CORE Service

    class MyService(CoreService):

#

## Service Attributes

#

Name used as a unique ID for this service and is required, no spaces.

        name = "MyService"

#

Allows you to group services within the GUI under a common name.

        group = "Utility"

#

Executables this service depends on to function, if executable is not on the path, service will not be loaded.

        executables = ()

#

Services that this service depends on for startup, tuple of service names.

        dependencies = ()

#

Directories that this service will create within a node.

        dirs = ()

#

Files that this service will generate, without a full path this file goes in the node’s directory. e.g. /tmp/pycore.12345/n1.conf/myfile

        configs = ("myservice1.sh", "myservice2.sh")

#

Commands used to start this service, any non-zero exit code will cause a failure.

        startup = ("sh %s" % configs[0], "sh %s" % configs[1])

#

Commands used to validate that a service was started, any non-zero exit code will cause a failure.

        validate = ()

#

Validation mode, used to determine startup success.

- NON_BLOCKING - runs startup commands, and validates success with validation commands
- BLOCKING - runs startup commands, and validates success with the startup commands themselves
- TIMER - runs startup commands, and validates success by waiting for “validation_timer” alone

        validation_mode = ServiceMode.NON_BLOCKING

#

Time in seconds for a service to wait for validation, before determining success in TIMER/NON_BLOCKING modes.

        validation_timer = 5

#

Period in seconds to wait before retrying validation, only used in NON_BLOCKING mode.

        validation_period = 0.5

#

Shutdown commands to stop this service.

        shutdown = ()

#

## On Load

        @classmethod
        def on_load(cls):

#

Provides a way to run some arbitrary logic when the service is loaded, possibly to help facilitate dynamic settings for the environment.

            pass

#

## Get Configs

        @classmethod
        def get_configs(cls, node):

#

Provides a way to dynamically generate the config files from the node a service will run. Defaults to the class definition and can be left out entirely if not needed.

            return cls.configs

#

## Generate Config

        @classmethod
        def generate_config(cls, node, filename):

#

Returns a string representation for a file, given the node the service is starting on the config filename that this information will be used for. This must be defined, if “configs” are defined.

            cfg = "#!/bin/sh\n"

            if filename == cls.configs[0]:
                cfg += "# auto-generated by MyService (sample.py)\n"
                for ifc in node.netifs():
                    cfg += 'echo "Node %s has interface %s"\n' % (node.name, ifc.name)
            elif filename == cls.configs[1]:
                cfg += "echo hello"

            return cfg

#

## Get Startup

        @classmethod
        def get_startup(cls, node):

#

Provides a way to dynamically generate the startup commands from the node a service will run. Defaults to the class definition and can be left out entirely if not needed.

            return cls.startup

#

## Get Validate

        @classmethod
        def get_validate(cls, node):

#

Provides a way to dynamically generate the validate commands from the node a service will run. Defaults to the class definition and can be left out entirely if not needed.

            return cls.validate