---
title: "Circular dependencies | Grafana Labs"
description: "Why component references can't form a loop"
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

Section 4 · Reading Alloy configuration

Why component references can't form a loop

Estimated time: 1 min

## Circular dependencies

In the previous slide, a reference created a dependency: `prometheus.remote_write.local_prom` depended on `local.file.example`. Alloy uses dependencies like that to decide which components to evaluate first. Because it needs a clear order, those dependencies can’t form a circle.

## Invalid examples

A component can’t reference itself:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
// Invalid: direct self-reference.
local.file "self_reference" {
  filename = local.file.self_reference.content
}
```

Components also can’t reference each other in a loop:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
// Invalid: circular dependency.
local.file "a" {
  filename = local.file.b.content
}

local.file "b" {
  filename = local.file.a.content
}
```

Here, `a` depends on `b`, while `b` depends on `a`. Neither can be evaluated first.

## How to spot a loop

When you read component references, follow each dependency in its direction. If following the references brings you back to a component you already visited, the configuration has a circular dependency and is invalid.