API Key

1. Add an "api key" column to the users table

Use a new migration file in the sql/schema directory to add a new column to the users table. I named my file 002_users_apikey.sql.

The "up" migration adds the column, and the "down" migration removes it.

Use a VARCHAR(64) that must be unique and not null. Using a string of a specific length does two things:

It ensures we don't accidentally store a key that's too long (type safety)
It's more performant than using a variable length TEXT column

Because we're enforcing the NOT NULL constraint, and we already have some users in the database, we need to set a default value for the column. A blank default would be a bit silly: that's no better than null! Instead, we'll generate valid API keys (256-bit hex values) using SQL. Here's the function I used:

encode(sha256(random()::text::bytea), 'hex')

When you're done, use goose postgres CONN up to perform the migration.

2. Create an API key for new users

Update your "create user" SQL query to use the same SQL function to generate API keys for new users.

3. Add a new SQL query to get a user by their API key

This query can live in the same file as the "create user" query, or you can make a new one - it's up to you.

4. Generate new Go code

Run sqlc generate to generate new Go code for your queries.

5. New endpoint: return the current user

Add a new endpoint that allows users to get their own user information. You'll need to parse the header and use your new query to get the user data.

Endpoint: GET /v1/users

Request headers: Authorization: ApiKey <key>

Example response body:

{
    "id": "3f8805e3-634c-49dd-a347-ab36479f3f83",
    "created_at": "2021-09-01T00:00:00Z",
    "updated_at": "2021-09-01T00:00:00Z",
    "name": "Lane",
    "api_key": "cca9688383ceaa25bd605575ac9700da94422aa397ef87e765c8df4438bc9942"
}

Test your endpoints with an HTTP client before moving on!

Don't forget that each time you update your queries or schema you'll need to regenerate your Go code with sqlc generate. If you update the schema you'll also need to migrate your database up (and maybe down).