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Framework for Making Multiple Lambda Commands Easier
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README.rst

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A flask like framework for building multiple lambdas in one library/package by utilizing lambda-uploader.

Quickstart

All you'll need to do to create a minimal lambada application is to add the following to a file called lambda.py :

from lambada import Lambada

tune = Lambada(role='arn:aws:iam:xxxxxxx:role/lambda')


@tune.dancer
def test_lambada(event, context):
    print('Event: {}'.format(event))

and a requirements.txt file that includes the lambada package (either lambada or https://github.com/Superpedestrian/lambada for the latest release or developer version respectively.

Much like a flask app, we now have a python file that is configured to upload a lambda function with the name test_lambada in your AWS account in the us-east-1 region (since that is the default), and the handler will be set to lamda.tune, again the default.

So what is this doing over just writing the same thing without this framework?

For one it gives you a command line toolset to test, list, and publish multiple functions to AWS as independant Lambda's with one code base.

Now that you have your code, you can run the lambada command line tool after running pip install -r requirements.txt to do something like lambada list

List of discovered lambda functions/dancers:

test_lambada:
    description:

You can also test that lambda with an event passed on the command line using lambada run test_lambada --event 'Hello' to get:

Event: Hello

which creates a faked AWS Context object before running the specified dancer.

From there we can also package the functions (the same package works for all defined dancers/Lambda functions). So without configuring any AWS credentials, we can run lambada package to create a zip file with all your requirements packaged up (from the earlier created requirements.txt) that you can manually upload to AWS Lambda through the Web interface or similar.

If you have your AWS API credentials setup, and the correct permissions, you can also run lambada upload to have the function created and/or versioned with the packaged code for each dancer.

Pretty neat so far, but where it starts to get cool is when there are many dancers with different requirements, VPCs, timeouts, security configuration, and memory requirements all in the same deployable package similar to the following. We're going to go ahead and call our file fouronthefloor.py just as a reference for the customization you can do, so the contents of fouronthefloor.py would look like:

from lambada import Lambada

chart = Lambada(
    handler='fouronthefloor.chart',
    role='arn:aws:iam:xxxxxxx:role/lambda',
    region='us-west-2',
    timeout=60,
    memory=128
)


@chart.dancer
def test_lambada(event, context):
    print('Event: {}'.format(event))


@chart.dancer(
    name='not_the_function_name',
    description='Cool description',
    memory=512,
    region='us-east-1',
    requirements=['requirements.txt', 'xtra_requirements.txt']
)
def cool_oneoff(event, context):
    print('Wow, so much memory! in a diff region and extra reqs!')


@chart.dancer(memory=1024, timeout=5)
def bob_loblaw(event, _):
    print('Such a great reference!')

Which gives a lambada list that looks like:

List of discovered lambda functions/dancers:

bob_loblaw:
    description:
    timeout: 5
    memory: 1024

test_lambada:
    description:

not_the_function_name:
    description: Cool description
    region: us-east-1
    requirements: ['requirements.txt', 'xtra_requirements.txt']
    memory: 512

And with a few lines we've created three lambdas with different execution requirements all with one lambada upload command. Such a simple seductive dance 😜.

Bouncers

AWS Lambda doesn't yet feature a way to add secure configuration items through environment variables (if it ever will), but there is often a need to have secrets that you don't want checked into source control such as API keys, passwords, certificates, etc. Generally it is nice to specify these with an out of source tree configuration file or environment variables. To achieve that here, we have the concept of Bouncer objects. This configuration object is created by default when you instantiate the Lambada class with a default configuration that you can use out of the box. The default :py:obj:`lambada.Bouncer` object looks for YAML configuration files in the following paths:

  • Path specified by the environment variable BOUNCER_CONFIG
  • The current working directory for lambada.yml
  • Your HOME directory for .lambada.yml
  • /etc/lambada.yml

and it does so in that order, terminating as soon as it successfully finds one.

In addition to those configuration files, it also will automatically add any variable prefixed with BOUNCER_ (again default, and can be changed to an arbitrary prefix) to the bouncer configuration. This means that without any code you can add configuration to your Lambada project by just adding say BOUNCER_API_KEY to your local configuration and referencing it in your code as tune.bouncer.api_key (assuming tune is the variable you chose for your lambada class.

Similarly, if you define a lambada.yml configuration file that looks like:

api_key: 1234abcd

it will be accessible in the same way as tune.bouncer.api_key.

It is worth noting that the environment variable will override the same named variable in your yaml file.

How this works in Lamda is that the Bouncer configuration on the Lambada is read when packaged for AWS and written to a _lambada.yml configuration and is looked for first when running in Lambda.

Customizing Bouncers

If those defaults don't work for you, you can also pass in your own Bouncer to the Lambada object on creation. It allows you to directly pass in the path to the configuration and/or change the environment variable prefix like so:

from lambada import Bouncer, Lambada

bouncer = Bouncer(config_file='foobar.yml', env_prefix='COOL_')
tune = Lambada(bouncer=bouncer, role=bouncer.role)

@tune.dancer
def test_lambada(event, context):
    print(bouncer.role)

as an example, which lets you use bouncer to help configure the Lambada object

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