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SAMWise (Beta)

“Come on, Mr. Frodo. I can’t carry it for you… but I can carry you!” -- Samwise Gamgee, Lord of the Rings

SAMWise was designed to carry the Serverless Application Model across the finish line and is a tool for packaging and deploying AWS Serverless Application Model applications. SAMWise is also an alternative to the AWS SAM CLI.

If you ❤️ love the AWS Serverless Application Model, CloudFormation and living an AWS native lifestyle but found the SAM CLI just a little bit wanting, SAMWise was created for you

Why SAMWise

SAMWise was born out of the desire to create the same enjoyable developer experience provided by the Serverless Framework but while using AWS's Serverless Application Model and native tooling as much as possible.

SAMWise's primary goal is to provide that same awesome developer experience without locking you into a third party tool, including this one. If you ever want to switch back to pure SAM/CloudFormation, SAMWise doesn't judge and will support you there and back again.

So, what was missing from the AWS CLI and SAM CLI?

One of the greatest things about the Serverless Framework CLI (or sls) is its ease of use and flexibility. With sls you could go from an idea to your first running Serverless application with just a small amount of yaml, a few lines of code and a single command line deploy. In addition sls provided a clear indication of success or failure after deploy along with a nice summary.

While all the building blocks are there with the AWS CLI, SAM CLI and API's, the native AWS tooling (at least today) falls short of this goal 😞


Pure awesome:

$ sls deploy --aws-profile <aws profile name> -s <namespace>

This just isn't possible with the SAM CLI (or sam) which requires at least 4 separate commands, each with different command line options to remember. When you are trying to rapidly iterate on a project you might find yourself running that sls command hundreds of times a day, doing this with sam becomes very painful, very fast.

Not so awesome:

$ sam build --use-container
$ sam package --s3-bucket my-cool-bucket --profile my-acount
$ sam deploy --capabilities CAPABILITY_IAM --region us-east-1 --stack-name my-cool-stack --parameter-overrides Namespace=dev
$ aws cloudformation describe-stack-events --stack-name my-cool-stack --profile my-account

There are a few other items that complicate matters like not being able to do simple variable substitution in a CloudFormation template, MFA support is poorly thought out and there is no way to extend the build system (e.g. plugins).

SAMWise to the rescue

SAMWise can be used in one of two ways. You can add a SAMWise block to the Metadata section of your SAM template.yaml file and rename it to samwise.yaml or leave your template.yaml 100% alone (and valid CFN) and link to it in your samwise.yaml

    Version: '1.0'
    DeployBucket: <S3 DEPLOY BUCKET>
    StackName: <YOUR STACK NAME>  # StackName is also provided as a #{Variable} or you can use the AWS:StackName pseudo parameter like a normal CFN template
    SamTemplate: template.yaml    # OPTIONAL if you don't want to touch your template.yaml
    Variables:                    # Provides simple #{Variable} token replacement within your template
      - RuntimeVar                # Will prompt or require via CLI the value for RuntimeVar
      - PreparedVar: SomeValue    # Prepared variable 

Then deploy your stack:

$ samwise deploy --profile <aws profile name> --namespace <namespace>


  • One line deploy with minimal command line arguments
  • Simple template variable substitution
  • First class support for MFA (with caching!)

A note on SAMWise's variable substitution feature

This feature/idea isn't fully baked just yet. It's purpose isn't to add a feature that CloudFormation doesn't have (which it does, mappings), but to allow for a more pleasant, easier on the eyes syntax for setting up mappings. For the moment however it is simple token substitution, in time however this will evolve to translate variables into native CloudFormation mappings before generating the final templates so it will be very easy to return to pure CloudFormation.

Language Support:

Currently only Python is supported, sorry ¯\_(ツ)_/¯

  • 🐍 Python 3.6 and 3.7


Here's what's on the SAMWise roadmap (in priority order):

  1. Better packaging
    • Right now, SAMWise uses the SAM CLI for packaging, but it's slow, doesn't cache much, and packages everything regardless if that code has changed or not.
    • Your code should be namespaced, right now your functions get thrown into the same folder with your package dependencies and it's only matter of time before a collision occurs
  2. During/Post-Deployment stats and notifications
    • Currently deployment output sucks and is practically non-existent, this is however one of the main goals of this tool so it's coming soon. No rest for the wicked and all that...
  3. Improve variable substitution and support the auto-generation of proper CFN mapping syntax
  4. Support more Languages/runtimes
    • It would be nice to support more than just Python. This is where the SAM CLI actually has done an amazing job and SAMWise has not
    • If SAMWise starts to show promise, then Javascript would likely be next


PR's and bug reports are welcome! If you want to discuss SAMWise, Serverless or even the weather, please feel free to reach out to any of the following contributors:



Last word

SAMWise exists to fill a need that right now the native tools from AWS do not and were preventing me from migrating from the Serverless framework to SAM. I would love nothing more than to sit down with the AWS SAM CLI team and figure out how to end-of-life SAMWise. Until then, well, development waits for no one!

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