tc is a graph-based, stateless, serverless application & infrastructure composer.

tc defines, creates and manages serveless entities such as functions, mutations, events, routes, states, queues and channels. tc compiles a tree of entities defined in the filesystem as a topology. This composable, namespaced, sandboxed, recursive, versioned and isomorphic topology is called a Cloud Functor.

The word functor was popularized by Ocaml's parameterized modules. These modules, called functors, are first class. Cloud functors are similar in that they are treated as first class and are composable much like Ocaml's elegant modules.

Why tc ?

tc is a tool that empowers developers, architects and release engineers to build a serverless system that is simple to define and easy to evolve.

1. Developers should not be drowning in permissions and provider-specific (AWS, GCP etc) services. Instead, tc provides a framework for developers to focus on domain-specific functions and abstract entities.
2. Architects should not be defining systems that are hard to implement or disconnected from the system definition. Instead, tc's topology is the system definition. The definition is representative of the entire system to a large extent with most of it inferred by tc.
3. Release engineers should not be managing manifests manually. Instead, tc provides a mechanism to deploy collection of namespaced topologies as an atomic unit. Canarys, A/B testing and rollbacks are much simpler to configure using tc

Key features of functors using tc

1. Composable Entities

At it's core, tc provides 7 entities (functions, events, mutations, queues, routes, states and channels) that are agnostic to any cloud provider. These entities are core primitives to define the topology of any serverless system. For example, consider the following topology definition:

name: example

routes:
  myposts:
    path: /api/posts
    method: GET
    function: bar
    event: MyEvent

events:
  consumes:
    MyEvent:
      function: foo
      channel: room1

channels:
  room1:
    handler: default

functions:
  remote:
    foo: github.com/bar/bar
  local:
    bar: ./bar

Now, /api/posts route calls function bar and generates an event MyEvent which are handled by functions that are locally defined (subdirectories) or remote (git repos). In this example, the event finally triggers a channel notification with the event's payload. We just defined the flow without specifying anything about infrastructure, permissions or the provider. This definition is good enough to render it in the cloud as services, as architecture diagrams and release manifests.

tc compile maps these entities to the provider's serverless constructs. If the provider is AWS (default), tc maps routes to API Gateway, events to Eventbridge, functions to either Lambda or ECS Fargate, channels to Appsync Events, mutations to Appsync Graphql and queues to SQS

2. Namespacing

If we run tc compile in the directory containing the above topology (topology.yml), we see that all the entities are namespaced. This implies there is room for several foo,bar or MyEvent entities in another topology. This also encourages developers to name the entities succinctly similar to function names in a module. With namespacing comes the benefit of having a single version of the namespace and thereby avoiding the need to manage the versions of sub-components.

3. Sandboxing

You can create a sandbox of this topology in the cloud (AWS is the default provider) using

tc create -s <sandbox-name> -e <aws-profile>

and can invoke (tc invoke -s sandbox -e env -p payload.json) this topology. This sandbox is also versioned and we can update specific entities or components in it. Sandboxing is fundamental to canary-based routing and deploys. tc create also knows how to build the functions, implicitly, for various language runtimes.

tc update -s sandbox -e env -c events|routes|mutations|functions|flow

4. Inference

tc compile generates a lot of the infrastructure (permissions, default configurations etc) boilerplate needed for the configured provider. Think of infrastructure as Types in a dynamic programming language. We can override the defaults or inferred configurations separate from the topology definition. For example we can have a repository layout as follows:

services/<topology>/<function>
infrastructure/<topology>/vars/<function>.json
infrastructure/<topology>/roles/<function>.json

This encourages developers to not leak infrastructure into domain-specific code or topology definition and vice versa. A topology definition could be rendered in with different infrastructure providers.

5. Recursive Topology

Functors can be created at any level in the code repository's heirarchy. They are like fractals where we can zoom in or out. For example, consider the following retail order management topology:

order/
|-- payment
|   |-- other-payment-processor
|   |   `-- handler.py
|   |-- stripe
|   |   |-- handler
|   |   `-- topology.yml
|   `-- topology.yml
`-- topology.yml

There are two sub-topologies in the root topology. order, payment and stripe are valid topologies. tc can create and manage sandboxes at any level preserving the integrity of the overall graph.

cd order
tc create -s <sandbox> -e <env> --recursive

This feature helps evolve the system and test individual nodes in isolation.

6. Isomorphic Topology

The output of tc compile is a self-contained, templated topology (or manifest) that can be rendered in any sandbox. The template variables are specific to the provider, sandbox and configuration. When we create (tc create) the sandbox with this templated topology, it implicitly resolves it by querying the provider. We can write custom resolvers to resolve these template variables by querying the configured provider (AWS, GCP etc).

tc compile | tc resolve -s sandbox -e env | tc create

We can replace the resolver with sed or a template renderer with values from ENV variables, SSM parameter store, Vault etc. For example:

tc compile | sed -i 's/{{API_GATEWAY}}/my-gateway/g' |tc create

The resolver can also be written in any language that is easy to use and query the provider, efficiently. The output of the compiler, the resolver and the sandbox's metadata as seen above are isomorphic. They are structurally the same and can be diffed like git-diff. Diffable infrastructure without having external state is a simple yet powerful feature.

This is all too abstract you say ? It is! Let's Get Started

Installation

Download the executable for your OS

Building your own

tc is written in Rust.

If you prefer to build tc yourself, install rustc/cargo.

Install Cargo/Rust https://www.rust-lang.org/tools/install

cd tc
cargo build --release
sudo mv target/release/tc /usr/local/bin/tc

Getting started

• 1. Bootstrap permissions
• 2. Our first function
• 3. Namespace your functions
• 4. Define the function DAG (flow)
• 5. Add a REST API to invoke ETL
• 6. Notify on completion
• 7. Implement the functions
• 8. Making it recursive
• 9. Configuring infrastructure

Caveat: this is a rough draft and we are still working on the documentation.

Now that we have installed tc and understood the features in abstract, let's try to walk through a basic tutorial of creating an ETL (Enhance-Transform-Load) flow using serverless entities.

In this tutorial, we will attempt to learn about the core concepts in tc.

1. Bootstrap permissions

Let's create some base IAM roles and policies for your sandbox. tc maps environments to AWS profiles. There can be several sandboxes per environment/account. For the sake of this example, let's say we have a profile called dev. This dev profile/account can have several dev sandboxes. Let's name our sandbox john.

tc create -s john -e dev -c base-roles

2. Our first function

A simple function looks like this. Let's call this function enhancer. Add a file named handler.py in a directory etl/enhancer.

etl/enhancer/handler.py:

def handler(event, context):
  return {'enhancer': 'abc'}

In the etl directory, we can now create the function by running the following command.

tc create -s <sandbox-name> -e <env>

Example: tc create -s john -e dev

This creates a lambda function named enhancer_john with the base role (tc-base-lambda-role) as the execution role.

3. Namespace your functions

Our etl directory now contains just one function called enhancer. Let's create the transformer and loader functions. Add the following files.

etl/transformer/handler.py

def handler(event, context):
  return {'transformer': 'ABC'}

loader/handler.py

def handler(event, context):
  return {'transformer': 'ABC'}

We should have the following directory contents:

etl
|-- enhancer
|   `-- handler.py
|-- loader
|   `-- handler.py
|-- topology.yml
`-- transformer
    `-- handler.py

Now that we have these 3 functions, we may want to collectively call them as etl. Let's create a file named topology.yml with the following contents:

name: etl

name is the namespace of these collection of functions. Now in the etl directory, we can run the following command to create a sandbox

tc create -s john -e dev

You should see the following output

Compiling topology
Resolving topology etl
1 nodes, 3 functions, 0 mutations, 0 events, 0 routes, 0 queues
Building transformer (python3.10/code)
Building enhancer (python3.10/code)
Building loader (python3.10/code)
Creating functor etl@john.dev/0.0.1
Creating function enhancer (211 B)
Creating function transformer (211 B)
Creating function loader (211 B)
Checking state enhancer (ok)
Time elapsed: 5.585 seconds

The resulting lambda functions are named 'namespace_function-name_sandbox'. If the name is sufficiently long, tc abbreviates it

We can test these functions, independently

cd enhancer
tc invoke -s john -e dev -p '{"somedata": 123}'

4. Define the function DAG (flow)

Now that we have these functions working in isolation, we may want to create a DAG of these functions. Let's define that flow:

name: etl

functions:
  enhancer:
    root: true
    function: transformer
  transformer:
    function: loader
  loader:
	end: true

tc dynamically figures out the orchestrator to use. By default, it uses Stepfunction (Express) to orchestrate the flow. tc automatically generates an intimidating stepfunction definition. You can inspect that by running tc compile -c flow

tc update -s john -e dev to update and create the flow.

5. Add a REST API to invoke ETL

name: etl

routes:
  /api/etl:
    method: POST
    function: enhancer

functions:
  enhancer:
    root: true
    function: transformer
  transformer:
    function: loader
  loader:
    event: Notify

Run tc update -s john -e dev -c routes to update the routes.

6. Notify on completion

name: etl

routes:
  /api/etl:
    method: POST
    function: enhancer

functions:
  enhancer:
    root: true
    function: transformer
  transformer:
    function: loader
  loader:
    event: Notify

events:
  Notify:
    channel: Subscription

channels:
  Subscription:
    function: default

Let's make loader output an event that pushes the status message to a websocket channel. tc update -s john -e dev to create/update the events and channels.

curl https://seuz7un8rc.execute-api.us-west-2.amazonaws.com/test/start-etl -X POST -d '{"hello": "world"}'
=> {"enhancer": "abc"}

7. Implement the functions

So far, we created a topology with basic functions, events, routes and a flow to connect them all. The functions themselves don't do much. Functions have depedencies, different runtimes or languages, platform-specific shared libraries and so forth. For example, we have want the enhancer to have some dependencies specified in say pyproject.toml or requirements.txt. Let's add a file named function.json in enhancer directory

enhancer/function.json

{
  "name": "enhancer",
  "description": "Ultimate enhancer",
  "runtime": {
    "lang": "python3.12",
    "package_type": "zip",
    "handler": "handler.handler",
  },
  "build": {
    "kind": "Inline",
    "command": "zip -9 -q lambda.zip *.py"
  },
}

and let's say we had the following deps in pyproject.toml

enhancer/pyproject.toml

[tool.poetry]
name = "enhancer"
version = "0.1.0"
description = ""
authors = ["fu <foo@fubar.com>"]

[tool.poetry.dependencies]
simplejson = "^3.19.2"
botocore = "^1.31.73"
boto3 = "^1.28.73"
pyyaml = "6.0.2"

Now update the function we created by running this from the etl directory

tc update -s john -e dev -c enhancer

The above command will build the dependencies in a docker container locally and update the function code with the depedencies.

There are several ways to package the depedencies depending on the runtime, size of the dependencies and so forth. Layering is another kind. Let's try and build the transformer using layers. Add the following in transformer/function.json

transformer/function.json

{
  "name": "transformer",
  "description": "Ultimate Transformer",
  "runtime": {
    "lang": "python3.12",
    "package_type": "zip",
    "handler": "handler.handler",
	"layers": ["transformer-deps"]
  }
}

The layers can be built independent of creating/deploying the code, as they don't change that often.

tc build --kind layer --name transformer-deps --publish -e dev
tc update -s john -e dev -c layers

With the above command, we built the dependencies in a docker container and updated the function(s) to use the latest version of the layer. See Build for details about building functions.

8. Making it recursive

We can make loader itself another sub-topology with it's own DAG of entities and still treat etl as the root topology (or functor). Let's add a topology file in loader.

etl/loader/topology.yml

name: loader

Now we can recursrively create the topologies from the root topology directory

tc create -s john -e dev --recursive

9. Configuring infrastructure

At times, we require more infrastructure-specific configuration, specific permissions, environment variables, runtime configuration.

We can specify an infra path in the topology

name: etl
infra: "../infra/etl"
routes: ..

In the specified infra directory, we can add environment/runtime variables for let's say enhancer.

../infra/etl/vars/enhancer.json

{
  "memory_size": 1024,
  "timeout": 800,
  "environment": {
    "GOOGLE_API_KEY": "ssm:/goo/api-key",
    "KEY": "VALUE"
  },
  "tags": {
    "developer": "john"
  }
}

If we need specific IAM permissions, do

../infra/etl/roles/enhancer.json

{
    "Statement": [
        {
            "Action": [
                "s3:PutObject",
                "s3:ListBucketVersions",
                "s3:ListBucket"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::bucket/*",
                "arn:aws:s3:::bucket"
                     ],
            "Sid": "AllowAccessToS3Bucket1"
        }

    ],
    "Version": "2012-10-17"
}

We may also need additional configuration that are specific to the provider (AWS etc). Add a key called config with the value as path to the file.

name: etl
infra: "../infra/etl"
config: "../tc.yaml"
routes: ..

See Config

Compiler

tc compile does the following:

1. Discovers functions recursively in the current directory.
2. Generates build instructions for the discovered functions.
3. Interns remote, shared and local functions
4. Reads the topology.yml file and validates it using input specification
5. Generates the target representations for these entities specific to a provider
6. Generates graphql output for mutations definition in topology.yml
7. Transpiles flow definitions to stepfn etc.
8. Generates checksum of all function directories
9. Detects circular flows

To generate the topology in curent directory

tc compile [--recursive]

To generate tree of all functions

cd examples/apps/retail
tc compile -c functions -f tree

retail
├╌╌ payment
┆   ├╌╌ payment_stripe_{{sandbox}}
┆   ┆   ├╌╌ python3.10
┆   ┆   ├╌╌ provided
┆   ┆   └╌╌
┆   └╌╌ payment_klarna_{{sandbox}}
┆       ├╌╌ python3.10
┆       ├╌╌ provided
┆       └╌╌
├╌╌ pricing
┆   └╌╌ pricing_resolver_{{sandbox}}
┆       ├╌╌ python3.10
┆       ├╌╌ provided
┆       └╌╌

Builder

• Inline
• Layer
• Image
  • Syncing base images
  • Inspecting the images
  • External parent image
• Slab
• Library
• Extension
• Recursive Builds

tc has a sophisticated builder that can build different kinds of artifacts with various language runtimes (Clojure, Janet, Rust, Ruby, Python, Node)

In the simplest case, when there are no dependencies in a function, we can specify how the code is packed (zipped) as follows in function.json:

{
  "name": "simple-function",
  "runtime": {
    "lang": "python3.10",
    "package_type": "zip",
    "handler": "handler.handler",
  },
  "build": {
    "command": "zip -9 lambda.zip *.py",
    "kind": "Code"
  }
}

Example

and then tc create -s <sandbox> -e <env> builds this function using the given command and creates it in the given sandbox and env.

Inline

The above is a pretty trivial example and it gets complicated as we start adding more dependencies. If the dependencies are reasonably small (< 50MB), we can inline those in the code's artifact (lambda.zip).

{
  "name": "python-inline-example",
  "runtime": {
    "lang": "python3.12",
    "package_type": "zip",
    "handler": "handler.handler",
    "layers": []
  },
  "build": {
    "kind": "Inline",
    "command": "zip -9 -q lambda.zip *.py"
  },
  "test": {
    "fixture": "python run-fixture.py",
    "command": "poetry test"
  }

}

Example

tc create -s <sandbox> -e <env> will implicitly build the artifact with inlined deps and create the function in the given sandbox and env. The dependencies are typically in lib/ including shared objects (.so files).

Layer

If inline build is heavy, we can try to layer the dependencies:

{
  "name": "ppd",
  "description": "my python layer",
  "runtime": {
    "lang": "python3.10",
    "package_type": "zip",
    "handler": "handler.handler",
    "layers": ["ppd-layer"]
  },
  "build": {
    "pre": [
      "yum install -y git",
      "yum install -y gcc gcc-c++"
    ],
    "kind": "Layer",

  }
}

Note that we have specified the list of layers the function uses. The layer itself can be built independent of the function, unlike Inline build kind.

tc build --kind layer
tc publish --name ppd-layer

We can then create or update the function with this layer. At times, we may want to update just the layers in an existing sandboxed function

tc update -s <sandbox> -e <env> -c layers

Image

While Layer and Inline build kind should suffice to pack most dependencies, there are cases where 250MB is not good enough. Container Image kind is a good option. However, building the deps and updating just the code is challenging using pure docker as you need to know the sequence to build. tc provides a mechanism to build a tree of images. For example:

{
  "name": "python-image-tree-example",
  "runtime": {
    "lang": "python3.10",
    "package_type": "image",
    "handler": "handler.handler"
  },

  "build": {
    "kind": "Image",
    "images": {
      "base": {
		  "version": "0.1.1",
		  "commands": [
			  "yum install -y git wget unzip",
			  "yum install -y gcc gcc-c++ libXext libSM libXrender"
		  ]
      },
      "code": {
		  "parent": "base",
		  "commands": []
      }
    }
  }
}

Example

In the above example, we define the base image with dependencies and code image that packs just the code. Note that code references base as the parent. Effectively, we can build a tree of images (say base dependencies, models, assets and code). These images can be built at any point in the lifecycle of the function. To build the base image do:

tc build --image base --publish

When --publish is specified, it publishes to the configured ECR repo [See Configuration]. Alternatively, TC_ECR_REPO env variable can be specified to override the config. The value of variable is the ECR repo URI

With python functions, the image can be built either by having a 'requirements.txt' file in the function directory or a pyproject.toml. tc build works with requirements.txt and poetry.

When all "parent" images have been built, tc create will create the code image just-in-time. The tag is the SHA1 checksum of the function directory. The code tag is typically of the format "{{repo}}/code:req-0d4043e5ae0ebc83f486ff26e8e30f3bd404b707""

We can also optionally build the code image.

tc build --image code --publish

Note that the child image uses the parent's version of the image as specified in the parent's block.

Syncing base images

While we can docker pull the base and code images locally, it is cumbersome to do it for all functions recursively by resolving their versions. tc build --sync pulls the base and code images based on current function checksums. Having a copy the base or parent code images allows us to do incremental updates much faster.

Inspecting the images

We can run tc build --shell in the function directory and access the bash shell. The shell is always on the code image of the current function checksum. Note that the code image using the Lambda Runtime Image as the source image.

External parent image

At times, we may need to use a parent image that is shared and defined in another function or build. The following function definition is an example that shows how to specify a parent URI in code image-spec.

{
  "name": "req-external-example",
  "description": "With external parent",
  "runtime": {
    "lang": "python3.10",
    "package_type": "image",
    "handler": "handler.handler"
  },

  "build": {
    "kind": "Image",
    "images": {
      "code": {
	"parent": "{{repo}}/base:req-0.1.1",
	"commands": []
      }
    }
  }
}

parent in the code image-spec is an URI. This is also a way to pin the parent image.

Slab

slab is an abstraction for building depedencies, assets and serving it via a network filesystem (EFS). An example function with slab looks like:

{
  "name": "python-example-snap",
  "description": "example function",
  "runtime": {
    "lang": "python3.12",
    "package_type": "zip",
    "mount_fs": true,
    "handler": "handler.handler",
    "layers": []
  },
  "build": {
    "kind": "slab"
  }
  "test": {
    "fixture": "python run-fixture.py",
    "command": "poetry test"
  }

}

tc build --kind slab --publish

This publishes the slab to EFS as configured (See Configuration)

Library

A library is a kind of build that recursively packs a collection of directories to serve as a single library in the target runtime.

For example, let's say we have the following directory structure

lib/
|-- bar
|   `-- lib.rb
|-- baz
|   `-- lib.rb
`-- foo
    `-- lib.rb

We can pack this as a library and publish it as a layer or a node in the image-tree. By default, tc publishes it as a layer.

cd lib
tc build --kind library --name mylib --publish --lang ruby

Why can't this just be of kind layer ? Layers typically have the dependencies resolved. Library is just standalone.

Extension

Lambda extensions are like sidecars that intercept the input/output payload events and can do arbitrary processing on them.

tc build --kind extension

Recursive Builds

To traverse through the topology and build the depedencies or code in parallel, do the following:

tc build [-kind code|image|layer] --recursive --publish

Deployer

Creating a Sandbox

cd <topology-dir>
tc create [--sandbox SANDBOX] [-e ENV]

Incremental updates

While developing, we often need to incrementally deploy certain components without recreating the entire topology. tc provides an update command that updates given component(s).

To update the code for a function (say page-mapper) in the current directory

tc update --sandbox test -e dev-af -c page-mapper

To update the IAM roles and policies

tc update --sandbox test -e dev-af -c roles

To update the eventbridge event rules:

tc update --sandbox test -e dev-af -c events

To update the environment variables or runtime parameters. Usually these are defined in infrastucture/tc//vars dir

tc update --sandbox test -e dev-af -c vars

To build and update layers

tc update --sandbox test -e dev-af -c layers

To update the Statemachine flow

tc update --sandbox test -e dev-af -c flow

To update tags across stepfns, lambdas, roles, policies, eventbridge rules etc

tc update --sandbox test -e dev-af -c tags

To update logging and tracing config

tc update --sandbox test -e dev-af -c logs

Invoker

• Specifying Payload
  • Invoking Events and Lambdas

Specifying Payload

To simply invoke a functor

tc invoke --sandbox main --env dev

By default, tc picks up a payload.json file in the current directory. You could optionally specify a payload file

tc invoke --sandbox main --env dev --payload payload.json

or via stdin

cat payload.json | tc invoke --sandbox main --env dev

or as a param

tc invoke --sandbox main --env dev --payload '{"data": "foo"}'

Invoking Events and Lambdas

By default, tc invokes a stepfn. We can also invoke a lambda or trigger an Eventbridge event

tc invoke --kind lambda -e dev --payload '{"data"...}'
tc invoke --kind event -e dev --payload '{"data"...}'

Emulator

• Lambdas
• Stepfunctions

Lambdas

To emulate the Lambda Runtime environment. The following command spins up a docker container with the defined layers in function.json, sets up the paths, environment variables, AWS access, local code and runtime parameters (mem, handlers etc)

cd <function-dir>
tc emulate

To run in foreground

tc emulate

You can now invoke a payload locally with this emulator

tc invoke --local [--payload <payload.json | json-str>]

Stepfunctions

tc also provides a stepfunction emulator. In your top-level topology directory, do:

tc emulate

This spins up a container and runs the emulator on http://localhost:8083

Details to follow on creating and executing [wip]

Inspector

tc provides a lightweight http-based app to inspect the topologies. This is still experimental.

To run the inspector, run tc inspect --trace in the root topology directory. For example:

cd examples/patterns
tc inspect --trace

Releaser

• Workflow
• Versioning
• Changelog

Workflow

Versioning

tc provides a sophisticated releaser module that can version at any level in the topology tree. Instead of managing the versions of each function, route, flow etc, we create a release tag at the top-level

tc tag --service <namespace> --next minor|major

This creates a tag with the etl prefix.

Changelog

To see the changelog of a specific topology

cd topology-dir
tc changelog

AI-123 Another command
AI-456 Thing got added

# or

tc changelog --between 0.8.1..0.8.6

To search for a specific text in all changelogs

cd root-topology-dir
tc changelog --search AI-1234

=> topology-name, version

Snapshotter

The snapshotter module takes a snapshot of a given sandbox and outputs the same datastructure as the compiler output. This isomorphic characteristic is useful to see the diffs between sandboxes.

For example the following outputs a JSON with the topology structure

cd topology-dir
tc snapshot -s stable -e qa -c topology

{
  "events": {},
  "functions": {
    "n_f_stable": {
      "code_size": "100 KB",
      "layers": {},
      "mem": 1024,
      "name": "n_f_stable",
      "revision": "e568c2865203",
      "tc_version": "0.8.71",
      "timeout": 180,
      "updated": "06:05:2025-15:48:32"
    },
...

Versions

To see versions of all root topologies in a given sandbox:

tc snapshot -s stable -e qa -f table|json

tc snapshot -s stable -e qa  -f table

 namespace  | sandbox | version  | frozen | tc_version | updated_at
------------+---------+----------+--------+------------+---------------------
 node1      | stable  | 0.0.6    |        | 0.0.3      | 04:09:2025-18:20:42
 node2      | stable  | 0.0.14   |        | 0.0.3      | 04:09:2025-18:19:15
 node3      | stable  | 0.0.15   |        | 0.0.3      | 04:09:2025-18:19:28
 node11     | stable  | 0.0.15   |        | 0.0.3      | 04:09:2025-18:19:28
 node12     | stable  | 0.0.2    |        | 0.6.262    | 12:13:2024-06:46:57

To see versions across profiles for a sandbox, provide a csv of profiles/envs:

tc snapshot -s stable -e qa,staging

 Topology   | qa       | staging
------------+----------+----------
 node2      | 0.0.27   | 0.0.24
 node3      | 0.0.6    | 0.0.6
 node4      | 0.0.15   | 0.0.15
 node5      | 0.0.26   | 0.0.26
 node7      | 0.12.125 | 0.12.125
 node8      | 0.2.29   | 0.2.29
 node9      | 0.2.102  | 0.2.102
 node10     | 0.1.24   | 0.1.24
 node12     | 0.0.147  | 0.0.143

Topology Specification

topology.yml

name: <namespace>
infra: <infra-path>

nodes:
  ignore: [<path>]
  dirs: [<path>]

functions:
  FunctionName:
    uri: <String>
    function: <String>
    event: <String>
    queue: <String>
    runtime: RuntimeSpec
    build: BuildSpec

events:
  EventName:
    producer: <String>
	doc_only: <false>
	nth: <sequence int>
	filter: <String>
	rule_name: <String>
    functions: [<String>]
    function: <String>
    mutation: <String>
    channel: <String>
    queue: <String>
    state: <String>

routes:
  Path:
    gateway: <String>
    authorizer: <String>
    method: <POST|GET|DELETE>
	path: <String>
    sync: <true>
    request_template: <String>
    response_template: <String>
    stage: <String>
    stage_variables: <String>
    function: <String>
    state: <String>
    queue: <String>

channels:
  ChannelName:
    function: <String>
    event: <String>

mutations:
  MutationName:
    function: <String>

queues:
  QueueName:
    function: <String>

states: ./states.json | <definition>  [optional]

infra is either an absolute or relative path to the infrastructure configs (vars, roles etc). This field is optional and tc tries best to discover the infrastructure path in the current git repo.

events, routes, functions, mutations, channels and flow are optional.

flow can contain a path to a step-function definition or an inline definition. tc automatically namespaces any inlined or external flow definition.

Entity Matrix

Not all entities are composable with each other. The following shows the compatibility Matrix and their implementation status

Function Specification

function.json file in the function directory is optional. tc infers the language and build instructions from the function code. However, for custom options, add a function.json that looks like the following

{
  "name": String,
  "runtime": RuntimeSpec,
  "build": BuildSpec,
  "infra": InfraSpec,
  "test": TestSpec
}

RuntimeSpec

BuildSpec

JSON Spec

{
  "name": "string",
  // Optional
  "dir": "string",
  // Optional
  "description": "string",
  // Optional
  "namespace": "string",
  // Optional
  "fqn": "string",
  // Optional
  "layer_name": "string",
  // Optional
  "version": "string",
  // Optional
  "revision": "string",
  // Optional
  "runtime": {
    "lang": "Python39" | "Python310" | "Python311" | "Python312" | "Python313" | "Ruby32" | "Java21" | "Rust" | "Node22" | "Node20",
    "handler": "string",
    "package_type": "string",
    // Optional
    "uri": "string",
    // Optional
    "mount_fs": true,
    // Optional
    "snapstart": true,
    "layers": [
      "string",
      /* ... */
    ],
    "extensions": [
      "string",
      /* ... */
    ]
  },
  // Optional
  "build": {
    "kind": "Code" | "Inline" | "Layer" | "Slab" | "Library" | "Extension" | "Runtime" | "Image",
    "pre": [
      "dnf install git -yy",
      /* ... */
    ],
    "post": [
      "string",
      /* ... */
    ],
    // Command to use when build kind is Code
    "command": "zip -9 lambda.zip *.py",
    "images": {
      "string": {
        // Optional
        "dir": "string",
        // Optional
        "parent": "string",
        // Optional
        "version": "string",
        "commands": [
          "string",
          /* ... */
        ]
      },
      /* ... */
    },
    "layers": {
      "string": {
        "commands": [
          "string",
          /* ... */
        ]
      },
      /* ... */
    }
  },
  // Optional
  "infra": {
    "dir": "string",
    // Optional
    "vars_file": "string",
    "role": {
      "name": "string",
      "path": "string"
    }
  }
}

Infrastructure Spec

Runtime Variables

Default Path: infrastructure/tc//vars/.json Override: infra.vars_file in function.json

{
  // Optional
  "memory_size": 123,
  // Optional
  "timeout": 123,
  // Optional
  "image_uri": "string",
  // Optional
  "provisioned_concurrency": 123,
  // Optional
  "reserved_concurrency": 123,
  // Optional
  "environment": {
    "string": "string",
    /* ... */
  },
  // Optional
  "network": {
    "subnets": [
      "string",
      /* ... */
    ],
    "security_groups": [
      "string",
      /* ... */
    ]
  },
  // Optional
  "filesystem": {
    "arn": "string",
    "mount_point": "string"
  },
  // Optional
  "tags": {
    "string": "string",
    /* ... */
  }
}

Roles

Config Specification

The following is a sample config file that you can place in your infrastructure root (infrastructure/tc/) or the path in TC_CONFIG_PATH. The configs have sections specific to the module and are optional with sane defaults.

compiler:
  verify: false
  graph_depth: 4
  default_infra_path: infrastructure/tc

resolver:
  incremental: false
  cache: false
  stable_sandbox: stable
  layer_promotions: true

deployer:
  guard_stable_updates: true
  rolling: false

builder:
  parallel: false
  autosplit: true
  max_package_size: 50000000
  ml_builder: true

aws:
  eventbridge:
    bus: EVENT_BUS
    rule_prefix: tc-
    default_role: tc-base-event-role
    default_region: us-west-2
    sandboxes: ["stable"]

  ecs:
    subnets: ["subnet-tag"]
    cluster: my-cluster

  stepfunction:
    default_role: tc-base-sfn-role
    default_region: us-west-2

  lambda:
    default_timeout: 180
    default_role: tc-base-lambda-role
    default_region: us-west-2
    layers_profile: LAYER_AWS_PROFILE
    fs_mountpoint: /mnt/assets

  api_gateway:
    api_name: GATEWAY_NAME
    default_region: us-west-2

Environment variables

tc uses special environment variables as feature bits and config overrides. The following is the list of TC environment variables:

TC_DIR

We don't have to always be in the topology or function directory to run a contextual tc command. TC_DIR env var sets the directory context

TC_DIR=/path/to/services/fubar tc create -s sandbox -e env

TC_USE_STABLE_LAYERS

At times we may need to use stable layers in non-stable sandboxes. This env variable allows us to use stable layers

TC_USE_STABLE_LAYERS=1 tc create -s sandbox -e env

TC_USE_SHARED_DEPS

This feature flag uses common deps (in EFS) instead of function-specific deps.

TC_USE_SHARED_DEPS=1 tc create -s sandbox -e env

TC_FORCE_BUILD

Tries various fallback strategies to build layers. One of the strategies is to build locally instead of a docker container. Another fallback is to use a specific version of python even if the transitive dependencies need specific version of Ruby or Python

TC_FORCE_BUILD=1 tc build --trace

TC_FORCE_DEPLOY

To create or update stable sandboxes (which are prohibited by default), use this var to override.

TC_FORCE_DEPLOY=1 tc create -s sandbox -e env

TC_UPDATE_METADATA

To update deploy metadata to a dynamodb table (the only stateful stuff in TC) for stable sandboxes

TC_UPDATE_METADATA=1 tc create -s staging -e env

TC_ECS_CLUSTER

Use this to override the ECS Cluster name

TC_ECS_CLUSTER=my-cluster tc create -s sandbox -e env

TC_USE_DEV_EFS

Experimental EFS with deduped deps and models

TC_USE_DEV_EFS=1 tc create ...

TC_SANDBOX

Set this to have a fixed sandbox name for all your sandboxes

TC_SANDBOX=my-branch tc create -e env

CLI Reference

This document contains the help content for the tc command-line program.

Command Overview:

• tc↴
• tc bootstrap↴
• tc build↴
• tc cache↴
• tc compile↴
• tc config↴
• tc create↴
• tc delete↴
• tc freeze↴
• tc emulate↴
• tc inspect↴
• tc invoke↴
• tc list↴
• tc publish↴
• tc resolve↴
• tc route↴
• tc scaffold↴
• tc test↴
• tc tag↴
• tc unfreeze↴
• tc update↴
• tc upgrade↴
• tc version↴
• tc doc↴

tc

Usage: tc <COMMAND>

Subcommands:

• bootstrap — Bootstrap IAM roles, extensions etc
• build — Build layers, extensions and pack function code
• cache — List or clear resolver cache
• compile — Compile a Topology
• config — Show config
• create — Create a sandboxed topology
• delete — Delete a sandboxed topology
• freeze — Freeze a sandbox and make it immutable
• emulate — Emulate Runtime environments
• inspect — Inspect via browser
• invoke — Invoke a topology synchronously or asynchronously
• list — List created entities
• publish — Publish layers
• resolve — Resolve a topology from functions, events, states description
• route — Route events to functors
• scaffold — Scaffold roles and infra vars
• test — Run unit tests for functions in the topology dir
• tag — Create semver tags scoped by a topology
• unfreeze — Unfreeze a sandbox and make it mutable
• update — Update components
• upgrade — upgrade tc version
• version — display current tc version
• doc — Generate documentation

tc bootstrap

Bootstrap IAM roles, extensions etc

Usage: tc bootstrap [OPTIONS]

Options:

• -R, --role <ROLE>
• -e, --profile <PROFILE>
• --create
• --delete
• --show
• -t, --trace

tc build

Build layers, extensions and pack function code

Usage: tc build [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -k, --kind <KIND>
• -n, --name <NAME>
• -i, --image <IMAGE>
• --clean
• -r, --recursive
• --dirty
• --merge
• --split
• --task <TASK>
• -t, --trace
• -p, --publish

tc cache

List or clear resolver cache

Usage: tc cache [OPTIONS]

Options:

• --clear
• --list
• -n, --namespace <NAMESPACE>
• -e, --env <ENV>
• -s, --sandbox <SANDBOX>
• -t, --trace

tc compile

Compile a Topology

Usage: tc compile [OPTIONS]

Options:

• --versions
• -r, --recursive
• -c, --component <COMPONENT>
• -f, --format <FORMAT>
• -t, --trace

tc config

Show config

Usage: tc config

tc create

Create a sandboxed topology

Usage: tc create [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -T, --topology <TOPOLOGY>
• --notify
• -r, --recursive
• --no-cache
• -t, --trace

tc delete

Delete a sandboxed topology

Usage: tc delete [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -c, --component <COMPONENT>
• -r, --recursive
• --no-cache
• -t, --trace

tc freeze

Freeze a sandbox and make it immutable

Usage: tc freeze [OPTIONS] --sandbox <SANDBOX>

Options:

• -d, --service <SERVICE>
• -e, --profile <PROFILE>
• -s, --sandbox <SANDBOX>
• --all
• -t, --trace

tc emulate

Emulate Runtime environments

Usage: tc emulate [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -s, --shell
• -d, --dev
• -t, --trace

tc inspect

Inspect via browser

Usage: tc inspect [OPTIONS]

Options:

• -t, --trace

tc invoke

Invoke a topology synchronously or asynchronously

Usage: tc invoke [OPTIONS]

Options:

• -p, --payload <PAYLOAD>
• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -n, --name <NAME>
• -S, --step <STEP>
• -k, --kind <KIND>
• --local
• --dumb
• -t, --trace

tc list

List created entities

Usage: tc list [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -r, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -c, --component <COMPONENT>
• -f, --format <FORMAT>
• -t, --trace

tc publish

Publish layers

Usage: tc publish [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -k, --kind <KIND>
• --name <NAME>
• --list
• --promote
• --demote
• --download
• --version <VERSION>
• --task <TASK>
• --target <TARGET>
• -t, --trace

tc resolve

Resolve a topology from functions, events, states description

Usage: tc resolve [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -c, --component <COMPONENT>
• -q, --quiet
• -r, --recursive
• --diff
• --no-cache
• -t, --trace

tc route

Route events to functors

Usage: tc route [OPTIONS] --service <SERVICE>

Options:

• -e, --profile <PROFILE>
• -E, --event <EVENT>
• -s, --sandbox <SANDBOX>
• -S, --service <SERVICE>
• -r, --rule <RULE>
• --list
• -t, --trace

tc scaffold

Scaffold roles and infra vars

Usage: tc scaffold

tc test

Run unit tests for functions in the topology dir

Usage: tc test [OPTIONS]

Options:

• -d, --dir <DIR>
• -l, --lang <LANG>
• --with-deps
• -t, --trace

tc tag

Create semver tags scoped by a topology

Usage: tc tag [OPTIONS]

Options:

• -n, --next <NEXT>
• -s, --service <SERVICE>
• --dry-run
• --push
• --unwind
• -S, --suffix <SUFFIX>
• -t, --trace

tc unfreeze

Unfreeze a sandbox and make it mutable

Usage: tc unfreeze [OPTIONS] --sandbox <SANDBOX>

Options:

• -d, --service <SERVICE>
• -e, --profile <PROFILE>
• -s, --sandbox <SANDBOX>
• --all
• -t, --trace

tc update

Update components

Usage: tc update [OPTIONS]

Options:

• -e, --profile <PROFILE>
• -R, --role <ROLE>
• -s, --sandbox <SANDBOX>
• -c, --component <COMPONENT>
• -a, --asset <ASSET>
• --notify
• -r, --recursive
• --no-cache
• -t, --trace

tc upgrade

upgrade tc version

Usage: tc upgrade [OPTIONS]

Options:

• -v, --version <VERSION>
• -t, --trace

tc version

display current tc version

Usage: tc version

tc doc

Generate documentation

Usage: tc doc [OPTIONS]

Options:

• -s, --spec <SPEC>