CloudFormation to diagram

How it works

1. 01

   Paste or drop your template

   A template.yaml or template.json as you deploy it, short tags like !Ref and !Sub included, or the template that cdk synth produces. Comments and the long Fn:: forms are fine.

2. 02

   See your stack

   Each resource becomes a card for its AWS service. VPCs and subnets become frames around what runs in them, and references between resources become connections.

3. 03

   Open it in Archboard

   Save it as a new diagram to rearrange cards, add notes, share a link, or export SVG and PNG. Signing up takes a Google or GitHub account.

What’s drawn from a CloudFormation template

The diagram comes from the Resources section of your template and these properties:

• ResourcesType

  Entries under Resources as cards for their Type, such as AWS::Lambda::Function or AWS::RDS::DBInstance. Glue types such as event source mappings, SNS subscriptions and security group ingress rules become connections, and custom resources appear as generic cards.

• !Ref!GetAtt!Sub

  A connection wherever a property points to another resource with Ref, Fn::GetAtt or a name inside Fn::Sub, in short or long form. References inside Fn::If are dashed, since a condition decides them.

• DependsOn

  DependsOn entries, whether they name one resource or list several, as dashed connections, unless a reference already links the same two resources. DependsOn on a resource that isn’t drawn, such as AWS::EC2::VPCGatewayAttachment, adds no connection.

• VpcIdSubnetId

  VPCs as frames that hold their subnets, and resources placed through VpcId, SubnetId, SubnetIds or VpcConfig: inside their subnet, or in the VPC frame when they span several subnets.

• EventsConnectors

  SAM function events as connections from the API route, labeled like POST /orders, or from the queue, bucket, stream or rule that starts the function. Schedules become trigger cards, and Connectors become Read or Write connections.

• aws:cdk:path

  For cdk synth output, cards take readable names from aws:cdk:path instead of generated logical IDs, constructs with two or more resources become frames, and CDKMetadata and CDK’s own helper resources are hidden.

• AWS::CloudFormation::Stack

  Each nested stack as one card, connected from the resources passed in as parameters and to the resources that read its outputs.

AWS SAM templates

A template with Transform: AWS::Serverless-2016-10-31 is read as written, without running sam build. Functions, APIs, HTTP APIs, simple tables, state machines and nested applications get their own cards, an API that SAM creates from a function event appears as a card too, and resources referenced in Policies are connected to their function. Globals only hold shared settings, so they aren’t drawn.

What a CloudFormation diagram leaves out

• Parameter values and defaults, Mappings, Outputs and the result of Conditions: every resource is drawn, even one a condition would skip, and property values aren’t shown.
• Resources inside a nested stack or SAM application, because its child template, given by TemplateURL or Location, isn’t fetched. Values imported from other stacks with Fn::ImportValue are counted, not drawn.
• Macros and transforms other than SAM, and Fn::ForEach loops: nothing is expanded, so a ForEach loop appears as one placeholder card.
• Stack status, drift, costs, or which services call each other at runtime. The diagram shows how the template wires resources, not live traffic.