Source code for provy.more.debian.cache.varnish

#!/usr/bin/python
# -*- coding: utf-8 -*-

'''
Roles in this namespace are meant to provide `Varnish <https://www.varnish-cache.org/>`_ configuration and execution utilities within Debian distributions.
'''

from provy.core import Role
from provy.more.debian.package.aptitude import AptitudeRole


class VarnishRole(Role):
    '''
    This role provides utility methods for Varnish configuration and execution within Debian distributions.

    Example:
    ::

        from provy.core import Role
        from provy.more.debian import VarnishRole

        class MySampleRole(Role):
            def provision(self):
                with self.using(VarnishRole) as role:
                    role.ensure_vcl('default.vcl', owner='user')
                    role.ensure_conf('default_varnish', owner='user')
    '''

    def provision(self):
        '''
        Installs `Varnish <https://www.varnish-cache.org/>`_ and its dependencies.
        This method should be called upon if overriden in base classes, or Varnish won't work properly in the remote server.

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    self.provision_role(VarnishRole) # does not need to be called if using with block.
        '''

        with self.using(AptitudeRole) as aptitude:
            aptitude.ensure_package_installed('varnish')

    def ensure_vcl(self, template, varnish_vcl_path='/etc/varnish/default.vcl', options={}, owner=None):
        '''
        Ensures that the VCL file at the specified path is up-to-date.

        :param template: The name of the VCL template file.
        :type template: :class:`str`
        :param varnish_vcl_path: The path that the VCL file will be in the remote server. Defaults to `/etc/varnish/default.vcl`.
        :type varnish_vcl_path: :class:`str`
        :param options: Dictionary of options to pass to the VCL template file. Extends context.
        :type options: :class:`dict`
        :param owner: Owner of the VCL file at the remote server. Defaults to :data:`None`.
        :type owner: :class:`str`

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    with self.using(VarnishRole) as role:
                        role.ensure_vcl('default.vcl', owner='user')
        '''

        result = self.update_file(template, varnish_vcl_path, options=options, sudo=True, owner=owner)
        if result:
            self.log('varnish vcl updated!')
            self.ensure_restart()

    def ensure_conf(self, template, varnish_conf_path='/etc/default/varnish', options={}, owner=None):
        '''
        Ensures that Varnish's configuration file at the specified path is up-to-date.

        :param template: The name of the VCL template file.
        :type template: :class:`str`
        :param varnish_conf_path: The path that the configuration file will be in the remote server. Defaults to `/etc/default/varnish`.
        :type varnish_conf_path: :class:`str`
        :param options: Dictionary of options to pass to the configuration template file. Extends context.
        :type options: :class:`dict`
        :param owner: Owner of the configuration file at the remote server. Defaults to :data:`None`.
        :type owner: :class:`str`

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    with self.using(VarnishRole) as role:
                        role.ensure_conf('default_varnish', owner='user')
        '''

        result = self.update_file(template, varnish_conf_path, options=options, sudo=True, owner=owner)
        if result:
            self.log('varnish conf updated!')
            self.ensure_restart()

    def cleanup(self):
        '''
        Restarts Varnish if it needs to be restarted (any changes made during this server's provisioning).

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    with self.using(VarnishRole) as role:
                        role.cleanup() # No need to call this if using a with block.
        '''
        super(VarnishRole, self).cleanup()
        if 'must-restart-varnish' in self.context and self.context['must-restart-varnish']:
            self.restart()

    def ensure_restart(self):
        '''
        Ensures that Varnish is restarted on cleanup phase.

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    with self.using(VarnishRole) as role:
                        role.ensure_restart() # No need to call this if using a with block.
        '''
        self.context['must-restart-varnish'] = True

    def restart(self):
        '''
        Forcefully restarts Varnish in the remote server.

        Example:
        ::

            from provy.core import Role
            from provy.more.debian import VarnishRole

            class MySampleRole(Role):
                def provision(self):
                    with self.using(VarnishRole) as role:
                        if not self.is_process_running('varnishd'):
                            role.restart()
        '''
        command = 'START=yes /etc/init.d/varnish restart'
        self.execute(command, sudo=True)