A .NET batch pipeline that ingests PDF invoices from Azure Blob Storage, extracts structured fields via GPT-4.1, generates vector embeddings, and indexes everything into Azure AI Search — ready to be queried via an Azure AI Foundry knowledge base.

Azure Blob Storage (PDFs)
        │
        ▼
PdfPig (local)             ← extracts raw text from PDF
        │
        ▼
GPT-4.1 (extraction)       ← extracts customer, amount, date, order ID, category...
        │
        ▼
Azure OpenAI Embeddings    ← text-embedding-3-large (3072 dims)
        │
        ▼
Azure AI Search Index      ← vector + semantic search
        │
        ▼
AI Foundry Knowledge Base  ← query interface for the support agent

1. EnsureIndex — creates or updates the AI Search index with vector and semantic config
2. ReadBlobs — lists all PDFs from the blob container, skipping already-indexed ones (capped at 500)
3. ExtractDocuments — extracts raw text via PdfPig, then sends the first 1000 chars to GPT-4.1 for structured field extraction
4. EmbedDocuments — generates 3072-dimension vectors via text-embedding-3-large
5. UploadDocuments — uploads documents + vectors to AI Search
6. EnsureKnowledgeSource — creates an AI Search knowledge source in AI Foundry
7. EnsureKnowledgeBase — creates a knowledge base backed by the index

• Azure CLI (az login)
• Terraform >= 1.0
• .NET 8 SDK
• Docker

Set your subscription ID in infra/terraform.tfvars:

subscription_id = "your-subscription-id"

Then run the 1 - Deploy Infrastructure GitHub Actions pipeline, or locally:

cd infra
terraform init
terraform apply -var="subscription_id=<your-sub-id>"

Place PDFs in the invoices/ folder and run 2 - Upload Invoices, or manually upload to the documents blob container.

Run 3 - Deploy Invoice Indexer — this builds the Docker image, pushes to ACR, and starts the ACI. The full pipeline runs automatically.

To re-index, restart the container:

az container start --resource-group rg-support-agent-dev --name aci-invoice-indexer-dev

Open Azure AI Foundry → Knowledge bases → invoices-knowledge-base → Test to query indexed invoices directly.

# Set environment variables (copy and fill in values)
cp infra/terraform.tfvars.example infra/terraform.tfvars

# Run locally
cd src/InvoiceIndexer
ASPNETCORE_ENVIRONMENT=Development dotnet run

Authenticate with:

az login
az account set --subscription <your-subscription-id>