Backend development guide

Suppose you’re interested in implementing a new feature in Infisical’s backend, let’s call it “feature-x.” Here are the general steps you should follow.

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Database schema migration

In order to run schema migrations you need to expose your database connection string. Create a .env.migration file to set the database connection URI for migration scripts, or alternatively, export the DB_CONNECTION_URI environment variable.

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Creating new database model

If your feature involves a change in the database, you need to first address this by generating the necessary database schemas.

1. If you’re adding a new table, update the TableName enum in /src/db/schemas/models.ts to include the new table name.
2. Create a new migration file by running npm run migration:new and give it a relevant name, such as feature-x.
3. Navigate to /src/db/migrations/<timestamp>_<feature-x>.ts.
4. Modify both the up and down functions to create or alter Postgres fields on migration up and to revert these changes on migration down, ensuring idempotency as outlined here.

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Generating TS Schemas

While typically you would need to manually write TS types for Knex type-sense, we have automated this process:

1. Start the server.
2. Run npm run migration:latest to apply all database changes.
3. Execute npm run generate:schema to automatically generate types and schemas using zod in the /src/db/schemas folder.
4. Update the barrel export in schema/index and include the new tables in /src/@types/knex.d.ts to enable type-sensing in Knex.js.

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Business Logic

Once the database changes are in place, it’s time to create the APIs for feature-x:

1. Execute npm run generate:component.
2. Choose option 1 for the service component.
3. Name the service in dash-case, like feature-x. This will create a feature-x folder in /src/services containing three files.
   1. feature-x-dal: The Database Access Layer functions.
   2. feature-x-service: The service layer where all the business logic is handled.
   3. feature-x-type: The types used by feature-x.

For reusable shared functions, set up a file named feature-x-fns.

Use the custom Infisical function ormify in src/lib/knex for simple database operations within the DAL.

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Connecting the Service Layer to the Server Layer

Server-related logic is handled in /src/server. To connect the service layer to the server layer, we use Fastify plugins for dependency injection:

1. Add the service type in the fastify.d.ts file under the service namespace of a FastifyServerInstance type.
2. In /src/server/routes/index.ts, instantiate the required dependencies for feature-x, such as the DAL and service layers, and then pass them to fastify.register("service,{...dependencies}).
3. This makes the service layer accessible within all routes under the Fastify service instance, accessed via server.services.<registered service name>.<function>.

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Writing API Routes

1. To create a route component, run npm generate:component.
2. Select option 3, type the router name in dash-case, and provide the version number. This will generate a router file in src/server/routes/v<version-number>/<router component name>
   1. Implement your logic to connect with the service layer as needed.
   2. Import the router component in the version folder’s index.ts. For instance, if it’s in v1, import it in v1/index.ts.
   3. Finally, register it under the appropriate prefix for access.