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Reactive dependencies enable automatic change propagation through your infrastructure. When a resource changes, pragma-os identifies all dependent resources and updates them automatically. Here’s how you declare this dependency chain: 
# Data source - the foundation
provider: gcp
resource: bigquery-dataset
name: documents
config:
  location: EU
---
# Embedding pipeline depends on the data source
provider: gcp
resource: bigquery-dataset
name: embeddings
depends_on:
  - gcp/bigquery-dataset/documents
config:
  source: "${gcp/bigquery-dataset/documents.outputs.dataset_id}"
---
# Vector index depends on embeddings
provider: gcp
resource: bigquery-dataset
name: vector-index
depends_on:
  - gcp/bigquery-dataset/embeddings
config:
  source: "${gcp/bigquery-dataset/embeddings.outputs.dataset_id}"
When documents changes, pragma-os:
  1. Detects the change
  2. Identifies all dependent resources
  3. Propagates updates through the graph
  4. Ensures everything stays in sync

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Declaring Dependencies

Use depends_on to establish relationships: 
provider: gcp
resource: bigquery-dataset
name: analytics
depends_on:
  - gcp/storage/data-lake
config:
  location: EU
The format is provider/resource/name, matching how resources are identified in pragma-os.

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Referencing Dependency Outputs

Access values from dependencies using field references: 
provider: gcp
resource: bigquery-dataset
name: analytics
depends_on:
  - gcp/storage/data-lake
config:
  source_bucket: "${gcp/storage/data-lake.outputs.bucket_url}"
  source_path: "${gcp/storage/data-lake.outputs.name}/data"
When data-lake updates, analytics receives the new output values automatically.

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Dependency Rules

Dependencies must exist and be ready. pragma-os won’t process a resource until all dependencies are in READY state. Circular dependencies are not allowed. If A depends on B, B cannot depend on A—this prevents infinite update loops. Changes cascade downward. When a resource updates, all resources that depend on it are notified and can react to the change.

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Next Steps

Resources

Understand resource lifecycle and states.

Providers

Learn how providers manage resources.