Data Quality Gate

---
name: data-quality-gate
description: "Builds a release-readiness gate for a data pipeline by gathering check results from one or more engines (dbt, Great Expectations, Soda), applying severity-aware pass/fail thresholds, and emitting a single go / no-go decision with per-check rationale. Use when authoring a CI step that must fail the build when data quality drops below thresholds."
---

# data-quality-gate

## Overview

The three engines (`dbt-testing`, `great-expectations`,
`soda-checks`) each produce their own per-check output: dbt writes
`run_results.json` ([dbt-run-results][1]), Great Expectations returns a
JSON result with a `success` flag and a `results` list
([gx-run-validation-definition][2]), and Soda emits a per-check
pass/fail summary in stdout (and to Soda Cloud) ([sodacl-overview][3]).

[1]: https://docs.getdbt.com/reference/artifacts/run-results-json
[2]: https://docs.greatexpectations.io/docs/core/run_validations/run_a_validation_definition
[3]: https://docs.soda.io/soda-v3/soda-cl-overview.md

This skill builds a **single release-readiness gate** that consumes those
heterogeneous outputs, applies severity-aware thresholds, and emits one
`go` / `no-go` decision the CI pipeline can act on. The skill is
deliberately engine-agnostic at the surface so a project can mix engines
(e.g. dbt for transformation tests + GX for ingestion validation + Soda
for cross-team observability) and still ship a single gate.

## When to use

- A pipeline runs more than one data-quality engine and needs a unified
  pass/fail summary (instead of one CI job per engine).
- Some checks are blocking (`severity: error`) and others should warn
  but not stop the pipeline (`severity: warn`) - the gate must
  distinguish.
- The team wants a structured artifact (JSON / markdown table) for PR
  comments, dashboards, or post-mortems - not just `exit 1`.
- A migration is rolling out new checks; the gate needs to honor a
  per-check "ratchet" (existing failures grandfathered, new failures
  block).

If a project uses only **one** engine and does not need severity
tiering, prefer that engine's native CI integration directly (see the
relevant skill's "CI integration" section) - this gate adds
machinery you do not need.

## Step 1 - Identify your sources

Enumerate every check-emitting engine the gate must consume. For each:

| Engine | Result artifact | Schema |
|---|---|---|
| dbt   | `target/run_results.json` | `.results[]` with `unique_id`, `status`, `failures`, `message` ([dbt-run-results][1]) |
| GX    | Python object from `validation_definition.run()` or `checkpoint.run()` - has `success: bool` plus `results[]` of per-expectation outcomes ([gx-run-validation-definition][2]) |
| Soda  | stdout summary from `soda scan`; non-zero exit on any failure ([sodacl-overview][3]) |
| Other | custom - must be flattened into the unified shape below |

Persist each engine's raw artifact as a CI build artifact (matching the
pattern from each skill's "CI integration" section) so the gate input
is reproducible and triageable.

## Step 2 - Define the unified check record

Flatten every engine's result into one record shape:

```json
{
  "check_id":     "dbt.test.orders.unique_order_id",
  "engine":       "dbt",
  "subject":      "orders.order_id",
  "status":       "fail",
  "severity":     "error",
  "failures":     12,
  "message":      "12 unique-key violations",
  "ratchet":      false,
  "owner":        "@data-platform"
}
```

| Field | Source |
|---|---|
| `check_id`  | engine-prefixed unique ID (`dbt.test.<unique_id>`, `gx.<suite>.<expectation_type>`, `soda.<dataset>.<check_text>`). |
| `engine`    | `dbt` / `gx` / `soda` / custom. |
| `subject`   | `<dataset>.<column>` or `<dataset>` for table-level checks. |
| `status`    | `pass` / `fail` / `warn` / `error` (engine-specific values normalized). |
| `severity`  | `error` (gate-blocking) or `warn` (gate-tolerable). Source: dbt `severity:` config; GX `meta` block convention; Soda `warn:` / `fail:` blocks. |
| `failures`  | row count for row-level checks; 0/1 for boolean checks. |
| `message`   | human-readable failure message. |
| `ratchet`   | optional - `true` if the failure existed before the ratchet date and is grandfathered. |
| `owner`     | optional - team/handle responsible for the dataset. |

## Step 3 - Apply the gate decision rule

Pseudocode:

```python
def gate_decision(records, *, allow_warn_failures=True):
    blockers = [
        r for r in records
        if r["status"] in ("fail", "error")
        and r["severity"] == "error"
        and not r.get("ratchet", False)
    ]
    warnings = [
        r for r in records
        if (r["status"] in ("fail", "error") and r["severity"] == "warn")
        or r["status"] == "warn"
    ]
    return {
        "verdict": "no-go" if blockers else "go",
        "blocker_count": len(blockers),
        "warning_count": len(warnings),
        "blockers": blockers,
        "warnings": warnings,
    }
```

The default is **strict-but-warn-tolerant**: any non-ratcheted error-severity
failure blocks; warn-severity failures and ratcheted records show in the
report but do not block.

For a stricter mode (no warn tolerance), set `allow_warn_failures=False`
and treat `warning_count > 0` as a blocker.

## Step 4 - Emit the artifact

The gate produces a markdown summary suitable for both `$GITHUB_STEP_SUMMARY`
and Soda Cloud / Slack pipelines:

```markdown
# Data Quality Gate - verdict: NO-GO

**Blockers: 2**

| Engine | Subject              | Check                  | Failures | Owner            |
|--------|----------------------|------------------------|---------:|------------------|
| dbt    | orders.order_id      | unique                 |       12 | @data-platform   |
| gx     | orders.discount_pct  | ExpectColumnValuesToBeBetween | 4 | @analytics-eng   |

**Warnings: 1**

| Engine | Subject     | Check               | Failures | Owner       |
|--------|-------------|---------------------|---------:|-------------|
| soda   | customers   | row_count > 0       |        0 | @platform   |
```

Plus a JSON sibling for downstream consumers:

```json
{
  "verdict": "no-go",
  "blocker_count": 2,
  "warning_count": 1,
  "blockers": [...],
  "warnings": [...]
}
```

A no-go verdict exits non-zero so the CI pipeline halts.

## Worked example

A full end-to-end collector (`scripts/run_quality_gate.py`) that reads each
engine's artifact, flattens it into the unified record shape, applies the Step 3
gate decision, and wires the gate into CI is in
[references/worked-example.md](references/worked-example.md).

## References

- `dbt-testing/SKILL.md` - dbt
  `run_results.json` schema and field meanings.
- `great-expectations/SKILL.md` - GX
  result object shape and `result_format` levels.
- `soda-checks/SKILL.md` - Soda CLI invocation
  and stdout summary format.
- [dbt-run-results][1] - canonical run_results.json schema.
- [gx-run-validation-definition][2] - GX `validation_definition.run()`
  return shape.
- [sodacl-overview][3] - SodaCL check vocabulary.