CI/CD pipeline for Flask - Step-by-Step Execution

Concept Flow - CI/CD pipeline for Flask

Code Commit to Repo

↓

Trigger CI Pipeline

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Run Tests

↓

Build Docker Image

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Push Image to Registry

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Trigger CD Pipeline

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Deploy to Server

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Run Smoke Tests

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Release Live

This flow shows how code changes trigger automated testing, building, and deployment steps to safely update a Flask app.

Execution Sample

Flask

git push origin main
# CI pipeline runs tests
# Build Docker image
# Push image to registry
# Deploy to server
# Run smoke tests

This sequence shows pushing code triggers tests, build, deploy, and verification steps automatically.

Execution Table

Step	Action	Result	Next Step
1	Code pushed to repo	Trigger CI pipeline	Run tests
2	Run tests	Tests pass	Build Docker image
3	Build Docker image	Image built successfully	Push image to registry
4	Push image to registry	Image pushed	Trigger CD pipeline
5	Trigger CD pipeline	Start deployment	Deploy to server
6	Deploy to server	App deployed	Run smoke tests
7	Run smoke tests	Smoke tests pass	Release live
8	Release live	App live with new version	End
9	If tests fail at step 2	Pipeline stops	Notify developer
10	If smoke tests fail at step 7	Rollback deployment	Notify ops

💡 Pipeline ends after successful release or stops on test failures.

Variable Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	Final
Code Version	v1.0	v1.1 (pushed)	v1.1 (image pushed)	v1.1 (deployed)	v1.1 (live)
Test Status	N/A	Pass	N/A	N/A	N/A
Deployment Status	Not deployed	Not deployed	Not deployed	Deployed	Live
Smoke Test Status	N/A	N/A	N/A	Pass	Pass

Key Moments - 3 Insights

Why does the pipeline stop if tests fail at step 2?

Because failing tests mean the code is not ready, so the pipeline stops to prevent bad code from deploying, as shown in execution_table row 9.

What happens if smoke tests fail after deployment?

The pipeline triggers a rollback to the previous stable version to avoid downtime, as shown in execution_table row 10.

Why do we build a Docker image after tests pass?

Building a Docker image packages the app consistently for deployment, ensuring the tested code is what runs live, as shown in execution_table row 3.

Visual Quiz - 3 Questions

Look at the execution table, what is the result after step 4?

A Image pushed to registry

B Tests fail

C App deployed

D Rollback triggered

💡 Hint

Check the 'Result' column for step 4 in the execution_table.

At which step does the pipeline stop if tests fail?

A Step 7

B Step 3

C Step 2

D Step 6

💡 Hint

Look for the failure condition related to tests in the execution_table rows.

If smoke tests fail, what is the immediate next action?

A Release live

B Rollback deployment

C Notify developer

D Build Docker image

💡 Hint

Refer to the execution_table row describing smoke test failure.

Concept Snapshot

CI/CD pipeline for Flask:
- Code push triggers CI pipeline
- Run automated tests; stop if fail
- Build Docker image if tests pass
- Push image to registry
- Deploy image to server
- Run smoke tests; rollback if fail
- Release live if all pass

Full Transcript

A CI/CD pipeline for a Flask app starts when code is pushed to the repository. This triggers the continuous integration pipeline, which runs automated tests. If tests pass, the pipeline builds a Docker image of the app and pushes it to a container registry. Then, the continuous deployment pipeline deploys the image to the server. After deployment, smoke tests run to verify the app is working. If smoke tests pass, the new version is released live. If any tests fail, the pipeline stops or rolls back to keep the app stable.