# Analyze an API made of several services

A backend made of several services is one API in Faustine: one namespace, one sign-in, one set of versions. Each service has its own code and its own analysis. Use this for REST services that share a host behind an edge which forwards by path, such as nginx, Kong or a cloud API gateway.

A backend-for-frontend or an orchestrator that declares its own routes is one service. Create it with [Create an API](https://docs.faustine.ai/apis/create-an-api/).

## Before you begin

- The code of each service, in repositories Faustine can read or as ZIP files. See [Connect GitHub](https://docs.faustine.ai/technologies/github/).
- The public prefix of each service: the path the edge puts in front of its routes, such as `/billing`.

## Create the API

1. In the portal, go to [**APIs**](https://auth.faustine.ai/go?to=%2Fintegrations%2Fapis) and select **New API**.
2. In **API type**, select **REST**.
3. In **Architecture**, select how the code is laid out, then **Continue**:
   - **Several services, one repository**: each service is a folder of the same repository.
   - **Several services, several repositories**: each service has its own repository or archive.
4. In **Details**, enter the **API name** and the **Namespace** that all the services share, then select **Continue**.
5. In **Services**, add the services. The steps depend on the architecture.
6. In **Keep the API up to date**, select **Automatic** or **Manual**. The step appears when at least one service comes from a repository.
7. In **Review & analyze**, select **Create & start analysis**.

An API can have up to 20 services.

### Add services from one repository

1. Select the repository and the branch.
2. Select **Find services**. Faustine lists the folders whose manifest declares an HTTP server, such as a `package.json`, `go.mod`, `pyproject` or `pom` file. Nothing is analyzed at this point.
3. Select the services that belong to this API.
4. For each one, check the **Name**, the **Namespace** and the **Public prefix**.

To add a folder that was not found, select **Add service manually** and enter its **Folder**.

### Add services from several repositories

1. Select **Add a service**.
2. Connect the service's repository, or upload its ZIP.
3. Enter its **Name** and **Namespace**. The **Language & framework** field defaults to **Let the analysis detect it**.
4. Enter its **Public prefix**. If the service already registers its routes with the full public path, select **No prefix — the service registers the full public path**.
5. Select **Save service**.

Repeat for each service. Two services cannot share a prefix, and a prefix is a fixed path without parameters.

## What happens after you create the API

The portal opens the API's **Services** tab. Faustine analyzes the services one at a time, and the operations of each service join the draft when its analysis finishes. You can review them while the next service runs.

The analysis looks for the service that issues the credentials the others accept. That service gets the **Auth provider** badge, and its sign-in becomes the sign-in of every service. If no service issues credentials, set the sign-in in the **Authentication** tab. See [Authentication](https://docs.faustine.ai/apis/authentication/).

The analysis of a service does not publish a version. When the services you need are ready, select **Publish**. All of them go into the same version. You can publish while another service is still in the queue.

## Manage the services

The **Services** tab lists each service with its public prefix, its code and the state of its analysis. Each row has a menu:

| Action | What it does |
| --- | --- |
| **Re-analyze** | Runs the analysis of that service again. The other services are not touched. |
| **Check for updates** | Compares the service's branch with the last analyzed commit and updates only what changed. |
| **Make it the auth provider** | Uses this service's sign-in for every service. |
| **Change the public prefix** | Moves the service's routes to another prefix. |
| **Edit name, namespace, technology** | Changes the service's label, namespace, framework hint and folder. |
| **Remove service** | Takes the service and its operations out of the draft. |

**Add service** adds one to an existing API, including an API that was created as one service. In that case the current code becomes the first service with no prefix, and no operation key or path changes. From then on, every analysis goes into the draft and you publish it yourself.

> **Warning:** Every operation key and path of a service starts with its public prefix. Changing the prefix renames those operations. The dialog shows how many operations, recipes, test cases, gateways and keys the change affects before you confirm.

When you remove a service, published versions keep its operations until you publish again.

## Find a service's operations

In the **Operations** tab, operations are grouped by service and then by resource. The row of chips over the table filters the list to one service.

## Next steps

- [The analysis](https://docs.faustine.ai/apis/analysis/): what each service's analysis writes.
- [Authentication](https://docs.faustine.ai/apis/authentication/): set the sign-in when no service issues credentials.
- [Versions and updates](https://docs.faustine.ai/apis/versions/): publish the draft once the services are ready.