Automate Cloud Architecture Diagrams with Python’s Diagrams Library

Background

Earlier I discovered the Python library diagrams , which can generate architecture diagrams directly from code, avoiding the tedious manual alignment of images in tools like draw.io.

Getting Started

The first requirement is Python 3.6+ and GraphViz. After installing the diagrams package with your preferred Python package manager, you can start creating diagrams.

from diagrams import Diagram

with Diagram("Simple Website Diagram") as diag:
    pass  # Shows an empty diagram in notebooks

The empty diagram appears as shown below.

Component Types

The library provides components for many providers. The most relevant for typical use cases are:

AWS / GCP / Azure – official cloud service assets.

Generic and On‑Prem – for cloud‑agnostic components.

Frameworks – to illustrate programming language elements.

SaaS – for services like Slack.

Diagram Concepts

Graph – the main object representing the diagram. Node – an abstract representation of a system component. Cluster – groups nodes together for readability. Edge – connects nodes.

Creating Your First Diagram

Step 1: Create a Workspace

from diagrams import Diagram, Cluster
from diagrams.aws.compute import EC2
from diagrams.aws.network import ELB, Route53
from diagrams.onprem.database import PostgreSQL
from diagrams.onprem.inmemory import Redis

with Diagram("Simple Website Diagram") as diag:
    dns = Route53("dns")
    load_balancer = ELB("Load Balancer")
    database = PostgreSQL("User Database")
    cache = Redis("Cache")
    svc_group = [EC2("Webserver 1"), EC2("Webserver 2"), EC2("Webserver 3")]
    diag

The diagram now shows all nodes:

Step 2: Add Nodes

We add AWS and on‑prem nodes for a load‑balanced website, using Route53, ELB, EC2 instances, PostgreSQL, and Redis.

Step 3: Group Nodes (Optional)

with Cluster("Webserver Cluster"):
    svc_group = [EC2("Webserver 1"), EC2("Webserver 2"), EC2("Webserver 3")]

Grouping improves readability:

Step 4: Connect Everything

with Diagram("Simple Website Diagram", direction='LR') as diag:
    dns = Route53("dns")
    load_balancer = ELB("Load Balancer")
    database = PostgreSQL("User Database")
    cache = Redis("Cache")
    with Cluster("Webserver Cluster"):
        svc_group = [EC2("Webserver 1"), EC2("Webserver 2"), EC2("Webserver 3")]
    dns >> load_balancer >> svc_group
    svc_group >> cache
    svc_group >> database
    diag

The final diagram shows the logical flow between components:

Conclusion

Using the diagrams library lets you generate clear, maintainable architecture diagrams programmatically, saving time on manual adjustments and making it easy to update designs as your infrastructure evolves.