Load Emerald data to DuckDB

Emerald Cloud Lab Constellation API is a REST API for programmatic access to ECL's Constellation database, allowing retrieval and manipulation of typed objects used by the Emerald Cloud Lab platform. Everything needed to build a working Emerald → DuckDB pipeline is on this page: the API's base URL, authentication, endpoints, pagination and incremental field — plus a prompt that hands the whole job to your coding agent.

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Build your Emerald to DuckDB pipeline

Paste this prompt into Claude, Codex, or Cursor. The agent does the rest.

PromptCopy prompt
Run uvx dlthub-init@latest to build a pipeline from Emerald to DuckDB and run it on dltHub

That scaffolds a dltHub workspace and installs the dltHub AI harness — the project rules, the secrets-management skill, and the dlt MCP server your agent needs to work safely. From there it reads the Emerald API, proposes the endpoints to load, then writes, runs and validates the pipeline while you review rather than type. Credentials are inspected through MCP tools, so your agent never reads secrets.toml itself. How the LLM-native workflow works →

Prefer to write it yourself? Every fact the agent uses is below.

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Emerald API at a glance

These values come from the Emerald API reference — the authoritative source if anything here looks out of date.

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How do I authenticate with the Emerald API?

Authentication is performed by obtaining a token via a POST request to the login endpoint (/ise/signintoken) and including this token in every subsequent request within the Authorization header as 'Bearer '.

1. Get your credentials

To obtain credentials for the Emerald Cloud Lab (ECL) Constellation REST API: 1) Log in to your Emerald Cloud Lab Command Center or developer portal account. 2) Send a POST request to the Login API endpoint at /ise/signintoken using your ECL credentials. 3) The API will return an AuthToken in the response body. 4) Use this token as a Bearer token in the 'Authorization' header ('Authorization: Bearer ') for all subsequent API requests.

2. Add them to .dlt/secrets.toml

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[sources.emerald_source]
emerald_auth_token = "your_auth_token_here"

dlt reads this file automatically at runtime. With the harness, the setup-secrets skill prompts you for the values and never handles the raw credential in chat. For production, see setting up credentials with dlt.

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What Emerald data can I load into DuckDB?

These are the Emerald endpoints dlt can load into DuckDB:

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How do I load only new Emerald records?

Emerald exposes updated_at on obj/type/, so dlt can request only the records that changed since the last run. Set it as the cursor_path and dlt tracks the high-water mark for you between runs.

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{"name": "types", "endpoint": {
    "path": "obj/type/",
    "incremental": {"cursor_path": "updated_at", "initial_value": "2024-01-01T00:00:00Z"},
}}

On the first run dlt loads everything from initial_value; on every run after that it requests only what changed and appends with write_disposition="merge" if you set a primary key. See incremental loading.

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What does the generated Emerald pipeline look like?

A standard dlt REST API pipeline — the same code you would write by hand, loading /ise/signintoken and /obj/search from the Emerald API into DuckDB:

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import dlt
from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources

@dlt.source
def emerald_source(auth_token=dlt.secrets.value):
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://constellation.emeraldcloudlab.com",
            "auth": {"type": "bearer", "token": auth_token},
        },
        "resources": [
            {"name": "types", "endpoint": {"path": "obj/type/"}},
            {"name": "type", "endpoint": {"path": "obj/type/{name}"}}
        ],
    }
    yield from rest_api_resources(config)


def load_emerald_to_duckdb() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="emerald_pipeline",
        destination="duckdb",
        dataset_name="emerald_data",
    )
    load_info = pipeline.run(emerald_source())
    print(load_info)


if __name__ == "__main__":
    load_emerald_to_duckdb()

Run it with python emerald_pipeline.py. The agent iterates on this until it loads cleanly — you review and approve, rather than write it from scratch.

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How do I query Emerald data in DuckDB?

dlt creates one table per resource. Query the loaded data with Python or SQL — or ask your agent to, through the MCP server's execute_sql_query tool.

Python (pandas DataFrame):

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import dlt

data = dlt.pipeline("emerald_pipeline").dataset()
df = data.types.df()
print(df.head())

SQL:

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SELECT * FROM emerald_data.types LIMIT 10;

See querying your data with dataset and exploring it in marimo notebooks.

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How do I deploy the Emerald to DuckDB pipeline in production?

The pipeline runs locally, which is ideal for prototyping and one-off analysis. When you need it on a schedule, monitored on every load, and shared with your team, deploy the same dlt code on the dltHub platform — no infrastructure to maintain. The prompt above already ends with "run it on dltHub", so your agent can take it there directly.

• Deploy & schedule — run the pipeline as a managed job with automatic retries.
• Monitor — observable job queues, alerting, and load metrics for every run.
• Transform — promote raw Emerald loads into governed, documented models.
• Visualize & share — explore data in notebooks and publish live dashboards instead of static screenshots.

Book a demo →

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What other destinations can I load Emerald data to?

dlt loads into any of these — only the destination argument changes:

Set dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. On the dltHub platform the same pipeline runs against a managed Iceberg lakehouse. See the full destinations list.

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Next steps

• Ready for production? Book a demo of the dltHub platform →
• dlt LLM-native workflow docs
• REST API source reference
• Join the dlt community on Slack