---
title: Project graph
---

import ProjectGraph from '@site/src/components/Docs/ProjectGraph';

The project graph is a representation of all configured
[projects in the workspace](../config/workspace#projects) and their relationships between each
other, and is represented internally as a directed acyclic graph (DAG). Below is a visual
representation of a project graph, composed of multiple applications and libraries, where both
project types depend on libraries.

<ProjectGraph />

:::info

The [`moon project-graph`](../commands/project-graph) command can be used to view the structure of
your workspace.

:::

## Relationships

A relationship is between a dependent (downstream project) and a dependency/requirement (upstream
project). Relationships are derived from source code and configuration files within the repository,
and fall into 1 of 2 categories:

### Explicit

These are dependencies that are explicitly defined in a project's [`moon.*`](../config/project)
config file, using the [`dependsOn`](../config/project#dependson) setting.

```yaml title="moon.yml"
dependsOn:
  - 'components'
  - id: 'utils'
    scope: 'peer'
```

### Implicit

These are dependencies that are implicitly discovered by moon when scanning the repository. How an
implicit dependency is discovered is based on a
[language's platform integration](./languages#tier-2--platform), and how that language's ecosystem
functions.

```json title="package.json"
{
  // ...
  "dependencies": {
    "@company/components": "workspace:*"
  },
  "peerDependencies": {
    "@company/utils": "workspace:*"
  }
}
```

:::caution

If a language is not officially supported by moon, then implicit dependencies will _not_ be
resolved. For unsupported languages, you must explicitly configure dependencies.

:::

### Scopes

Every relationship is categorized into a scope that describes the type of relationship between the
parent and child. Scopes are currently used for [project syncing](../commands/sync) and deep Docker
integration.

- **Production** - Dependency is required in production, _will not be_ pruned in production
  environments, and will sync as a production dependency.
- **Development** - Dependency is required in development and production, _will be_ pruned from
  production environments, and will sync as a development-only dependency.
- **Build** - Dependency is required for building only, and will sync as a build dependency.
- **Peer** - Dependency is a peer requirement, with language specific semantics. Will sync as a peer
  dependency when applicable.

## What is the graph used for?

Great question, the project graph is used throughout the codebase to accomplish a variety of
functions, but mainly:

- Is fed into the [task graph](./task-graph) to determine relationships of tasks between other
  tasks, and across projects.
- Powers our [Docker](../guides/docker) layer caching and scaffolding implementations.
- Utilized for [project syncing](../commands/sync) to ensure a healthy repository state.
- Determines affected projects in [continuous integration](../guides/ci) workflows.
