Tasks

Bespin’s mechanism for doing anything are tasks. By default Bespin comes with a number of tasks as describe below:

Default tasks

tail

Tail the deployment of a stack

show

Show what stacks we have in layered order.

When combined with the --flat option, the stacks are shown as a flat list instead of in layers.

deploy

Deploy a particular stack

params

Print out the params

become

Print export statements for assuming an amazon iam role

outputs

Print out the outputs

execute

Exec a command using assumed credentials

bastion

SSH into the bastion

downtime

Downtime this stack in alerting systems

instances

Find and ssh into instances

list_tasks

List the available_tasks

undowntime

UnDowntime this stack in alerting systems

deploy_plan

Deploy a predefined list of stacks in order

sanity_check

Sanity check a stack and it’s dependencies

num_instances

Count the number of running instances.

print_variable

Prints out a variable from the stack

scale_instances

Change the number of instances in the stack’s auto_scaling_group

encrypt_password

Convert plain text password into crypto text

publish_artifacts

Build and publish an artifact

sanity_check_plan

sanity check a predefined list of stacks in order

confirm_deployment

Confirm deployment via SNS notification for each instance and/or url checks

validate_templates

Validates all stack templates and parameters against CloudFormation

clean_old_artifacts

Cleanup old artifacts

wait_for_dns_switch

Periodically check dns until all our sites point to where they should be pointing to for specified environment

command_on_instances

Run a shell command on all the instances in the stack

sync_netscaler_config

Sync netscaler configuration with the specified netscaler

switch_dns_traffic_to

Switch dns traffic to some environment

create_stackdriver_event

Create an event in stackdriver

enable_server_in_netscaler

Disable a server in the netscaler

note_deployment_in_newrelic

Note the deployment in newrelic

disable_server_in_netscaler

Enable a server in the netscaler

resume_cloudformation_actions

Resumes all schedule actions on a cloudformation stack

suspend_cloudformation_actions

Suspends all schedule actions on a cloudformation stack

Custom Tasks

There are two ways you can create custom tasks.

The first way is to define tasks as part of a stack definition:

---

stacks:
  app:
    [..]

    tasks:
      deploy_app:
        action: deploy

Will mean that you can run bespin deploy_app dev and it will run the deploy action for your app stack.

Tasks have several options:

action

The task to run. Note that the stack will default to the stack you’ve defined this task on.

options

Extra options to merge into the stack configuration when running the task.

overrides

Extra options to merge into the root of the configuration when running the task.

description

A description that is shown for this task when you ask Bespin to list all the tasks.

The second way of defining custom tasks is with the extra_imports option.

For example, let’s say you have the following layout:

bespin.yml
app.json
scripts.py

And your bespin.yml looked like:

---

bespin:
  extra_imports:
  - ["{config_root}", "scripts"]

stacks:
  app:
    [..]

Then before Bespin looks for tasks it will first import the python module named scripts that lives in the folder where bespin.yml is defined. So in this case, the scripts.py.

The only thing scripts.py needs is a __bespin__(bespin, task_maker) method where bespin is the Bespin object and task_maker is a function that may be used to register tasks.

For example:

def __bespin__(bespin, task_maker):
  task_maker("deploy_app", "Deploy the app stack", action="deploy").specify_stack("app")

Here we have defined the deploy_app action that will deploy the app stack.

We can do something more interesting if we also define a custom action:

from bespin.tasks import a_task

def __bespin__(bespin, task_maker):
  task_maker("list_amis", "List amis with a particular tag")

@a_task(needs_credentials=True)
def list_amis(overview, configuration, **kwargs):
  credentials = configuration['bespin'].credentials
  amis = credentials.ec2.get_all_images(filters={"tag:application": "MyCreatedAmis"})
  for ami in amis:
    print(ami.id)

And then we can do bespin list_amis dev and it will find all the Amis that have an application tag with MyCreatedAmis.