migrations.py

#!/usr/bin/env python
'''Stack migration definitions

The migration definitions are used to defined the specific functions
used for migrating stacks between specific versions.

The `MIGRATIONS` dictionary contains the mappings between
`'%(from)s-%(to)s'` version strings and the specific function to
perform the migration.  The specific migration functions should be
denoted as private to this module.

'''


def migrate_083_084(stack, **kwargs):
    try:
        # Move meta variables to regular values
        region = stack.region
        cluster = stack.cluster
        created = stack.created
        creator = stack.creator
        uuid = stack.uuid
        # Remove meta variables
        stack.unset('region', meta=True)
        stack.unset('cluster', meta=True)
        stack.unset('created', meta=True)
        stack.unset('creator', meta=True)
        stack.unset('uuid', meta=True)
        stack.unset('stack_version', meta=True)
        stack.unset('state', meta=True)
        # Add old meta variables as non-meta
        stack.set('region', region)
        stack.set('cluster', cluster)
        stack.set('created', created)
        stack.set('creator', creator)
        stack.set('uuid', uuid)
        stack.set('stack_version', '0.8.4')
        stack.set('state', 'active')
        # Remove Resources Key, These are no longer used since 0.8.0.
        stack.unset('resources')

        # Save
        stack._save(changelog='Migrated stack from 0.8.3 to 0.8.4')
    except Exception as ex:
        if kwargs.get('verbose', False):
            print(ex)
        stack.update_state('corrupt')


def migrate_082_083(stack, **kwargs):
    import os
    from . import stack as stk

    try:
        git_sha = os.environ['GIT_REV']

        environment_name = 'homer'

        stack.set('environment_name', environment_name)

        stk.upgrade_cfn_stack(stack, git_sha, **kwargs)

        stack.set('stack_version', '0.8.3', meta=True)
        stack.update_state('active')
    except Exception as ex:
        if kwargs.get('verbose', False):
            print(ex)
        stack.update_state('corrupt')


def migrate_081_082(stack, **kwargs):
    import os
    from . import stack as stk

    try:
        git_sha = os.environ['GIT_REV']

        environment = 'prod' if stack.name == 'prod' else 'dev'

        stack.set('environment', environment)

        stk.upgrade_cfn_stack(stack, git_sha, **kwargs)

        stack.set('stack_version', '0.8.2', meta=True)
        stack.update_state('active')
    except Exception as ex:
        if kwargs.get('verbose', False):
            print(ex)
        stack.update_state('corrupt')


def migrate_080_081(stack, **kwargs):
    import os
    from . import stack as stk

    try:
        git_sha = os.environ['GIT_REV']

        stk.upgrade_cfn_stack(stack, git_sha, **kwargs)

        stack.set('stack_version', '0.8.1', meta=True)
        stack.update_state('active')
    except Exception as ex:
        if kwargs.get('verbose', False):
            print(ex)
        stack.update_state('corrupt')


def migrate_071_080(stack, **kwargs):

    import os
    import shellish
    import boto3
    import uuid
    from . import stack as stk
    from . import cloudformation

    def describe_service(cluster, service, region):
        client = boto3.client('ecs', region_name=region)
        return client.describe_services(
            cluster=cluster,
            services=[service]
        ).get('services', [None])[0]

    def remove_elb_target_group(region, arn=None):
        elb_api = boto3.client('elbv2', region_name=region)
        elb_api.delete_target_group(TargetGroupArn=arn)

    def remove_elb_listener(region, arn=None):
        elb_api = boto3.client('elbv2', region_name=region)
        elb_api.delete_listener(ListenerArn=arn)

    def remove_elb(region, arn=None):
        elb_api = boto3.client('elbv2', region_name=region)
        elb_api.delete_load_balancer(LoadBalancerArn=arn)

    def remove_ecs_service(region, cluster=None, name=None):
        ecs_api = boto3.client('ecs', region_name=region)
        ecs_api.update_service(cluster=cluster, service=name, desiredCount=0)
        ecs_api.delete_service(cluster=cluster, service=name)

    def remove_task_definition(region, family=None):
        ecs_api = boto3.client('ecs', region_name=region)
        paginator = ecs_api.get_paginator('list_task_definitions')
        for page in paginator.paginate(familyPrefix=family, status='ACTIVE'):
            for arn in page['taskDefinitionArns']:
                print("\tDeregistering: %s" % arn)
                ecs_api.deregister_task_definition(taskDefinition=arn)

    def remove_dns(region, name=None, record=None, hosted_zone_id=None):
        change = {
            'Changes': [{
                'Action': 'DELETE',
                'ResourceRecordSet': record
            }]
        }
        r53_api = boto3.client('route53')
        r53_api.change_resource_record_sets(HostedZoneId=hosted_zone_id,
                                            ChangeBatch=change)

    def create_cfn_stack(stack, **kwargs):

        domain = '.'.join(stack.dns[0].split('.')[1:])
        hostnames = [x.split('.')[0] for x in stack.dns]
        app_service = describe_service(
            stack.cluster,
            'odyssey-%s-app' % stack.name,
            stack.region)
        stack.set('app_service_count', app_service['desiredCount'])
        stack.set('uuid', str(uuid.uuid4()), meta=True)
        stack.set('version', stack.name)

        stk.create_stack_aws_resources(
            stack,
            region=stack.region,
            ecs_cluster=stack.cluster,
            elb_security_group='homer-elb-sg',
            elb_internal_security_group='homer-int-elb-sg',
            eni_security_group='homer-ecs-sg',
            rds_config='default',
            pub_subnet_prefix='homer-public',
            priv_subnet_prefix='homer-private',
            https_cert_hostname='*',
            domain=domain,
            hostnames=hostnames,
            create_database=False,
            **kwargs,
        )

    def remove_resources(stack):
        resource_removers = {
            'elb': remove_elb,
            'elb-target-group': remove_elb_target_group,
            'elb-listener': remove_elb_listener,
            'ecs-service': remove_ecs_service,
            'ecs-task-definition': remove_task_definition,
            'dns': remove_dns,
        }

        try:
            for x in reversed(stack.resources):
                print('Removing: %s - %s' % (x['kind'], x['ident']))
                try:
                    resource_removers[x['kind']](stack.region, **x['options'])
                except Exception as e:
                    raise e from None
        except BaseException as e:
            shellish.vtmlprint("<red><b>CRITICAL ERROR: %s" % e)
            stack.update_state('corrupt')
            raise e

    if stack is None:
        raise SystemExit('Stack not found: %s' % stack.name)

    try:
        create_cfn_stack(stack, **{**kwargs, **{'IsMigration': 'True'}})

        cfn_stack = cloudformation.watch_stack_progress(stack, **kwargs)

        if kwargs.get('verbose', False):
            print(cfn_stack)

        if cfn_stack is None or 'ROLLBACK' in cfn_stack['StackStatus']:
            stack.update_state('corrupt')
            raise SystemExit("Unable to create cloudformation resources")

        remove_resources(stack)

        git_sha = os.environ['GIT_REV']

        stk.upgrade_cfn_stack(stack, git_sha, **kwargs)

        stack.set('stack_version', '0.8.0', meta=True)
        stack.update_state('active')

    except Exception as ex:
        if kwargs.get('verbose', False):
            print(ex)
        stack.update_state('corrupt')


MIGRATIONS = {
    '0.7.1-0.8.0': migrate_071_080,
    '0.8.0-0.8.1': migrate_080_081,
    '0.8.1-0.8.2': migrate_081_082,
    '0.8.2-0.8.3': migrate_082_083,
    '0.8.3-0.8.4': migrate_083_084,
}


def migrate_stack(stack, from_version, target_version, **kwargs):
    '''Entry point for stack migration'''
    migration_str = '%s-%s' % (from_version, target_version)
    if migration_str not in MIGRATIONS:
        raise SystemExit("No migration path found for %s" % migration_str)

    MIGRATIONS[migration_str](stack, **kwargs)