Login and Sessions

Goal

This snapshot advances Baltic Post by teaching you to authenticate with signed session cookies.

Every numbered folder is a complete app. Run this stage independently, then compare it with the previous folder.

Prerequisites

Use JDK 17+, Gradle, and Docker for Postgres stages.

Port 8090 must be free. Copy .env.example before starting database stages.

• JDK 17+ and Gradle
• A code editor and terminal
• Docker from part 4 onward

Concepts

Ktor sessions store an opaque cookie. Keep only the user id in the session.

Keep handlers thin: routes accept input, Exposed tables enforce rules, and FreeMarker escapes output by default.

Walkthrough

Verify email/password, set session, clear on logout.

Read the example, then open the matching snapshot. The repository includes the surrounding setup and error handling.

call.sessions.set(UserSession(userId = user.id))

Run and verify

Enter 07-Login-And-Sessions, run Gradle, copy .env.example, and start Ktor on port 8090.

Open http://127.0.0.1:8090. Watch the terminal for validation and database errors.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-ktor-blog.git
cd fcc-ktor-blog/07-Login-And-Sessions
cp .env.example .env
./gradlew run

Troubleshooting

Changing SESSION_SECRET invalidates cookies.

For database failures, confirm Docker and the baltic_NN name when applicable. Never commit .env or local.properties secrets.

• Read the first error first
• Restart after environment changes
• Never commit secrets

Try this

Log in, restart, confirm session, then log out.

Test a happy path and one invalid or unauthorized request.

• Make one small change
• Test it in the browser
• Compare with the next snapshot only after it works