# Debug Pipeline

> Diagnose Harness pipeline executions via MCP. Analyzes any execution (failed or successful) to produce structured reports with stage/step breakdown, timing, bottlenecks, failure details, chained pipeline drill-down, and execution logs. Use when asked to debug a pipeline, investigate a failure, find out why a build failed, analyze pipeline errors, check execution logs, review execution performance, or find bottlenecks. Trigger phrases: debug pipeline, pipeline failed, why did my build fail, analyze failure, pipeline error, execution logs, fix pipeline, execution bottleneck, slow pipeline.

- Skill: `harness/debug-pipeline` (Agent Skill)
- Install (CLI): `npx skillmds@latest add harness/debug-pipeline`
- Raw SKILL.md: https://api.skillmd.com/api/skills/harness/debug-pipeline/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- License: Apache-2.0
- Author: harness (https://skillmd.com/u/harness)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/harness/debug-pipeline

---


# Debug Pipeline

Diagnose pipeline executions and suggest fixes via MCP.

## Instructions

### Step 1: Diagnose Execution (Preferred)

Use the dedicated diagnosis tool. It accepts an execution_id, pipeline_id (auto-fetches latest execution), or a Harness URL:

```
Call MCP tool: harness_diagnose
Parameters:
  pipeline_id: "<pipeline_identifier>"   # or execution_id or url
  org_id: "<organization>"
  project_id: "<project>"
```

This returns a structured report with stage/step breakdown, timing, bottlenecks, and failure details in one call. It also automatically follows chained (child) pipeline failures.

### Step 1b: Full Diagnostic Mode

For deeper analysis, request logs and pipeline YAML:

```
Call MCP tool: harness_diagnose
Parameters:
  execution_id: "<execution_id>"
  org_id: "<organization>"
  project_id: "<project>"
  summary: false               # raw diagnostic payload
  include_yaml: true           # include pipeline definition
  include_logs: true           # include failed step logs
  log_snippet_lines: 120       # tail N lines per step (0 = unlimited)
  max_failed_steps: 5          # cap number of steps to fetch logs for
```

### Diagnose Parameters

| Parameter | Default | Description |
|-----------|---------|-------------|
| `execution_id` | -- | Specific execution to analyze |
| `pipeline_id` | -- | Fetch latest execution for this pipeline |
| `url` | -- | Harness UI URL (auto-extracts IDs) |
| `summary` | true | Structured report (true) or raw payload (false) |
| `include_yaml` | false (summary) / true (raw) | Include pipeline YAML definition |
| `include_logs` | false (summary) / true (raw) | Include failed step logs |
| `log_snippet_lines` | 120 | Max log lines per step (tail). 0 = unlimited |
| `max_failed_steps` | 5 | Max steps to fetch logs for. 0 = unlimited |

### Step 2: Project Health Overview

Check overall project health for context:

```
Call MCP tool: harness_status
Parameters:
  org_id: "<organization>"
  project_id: "<project>"
```

Shows recent failed executions, running executions, and deployment activity.

### Step 3: Find Failed Executions (if needed)

```
Call MCP tool: harness_list
Parameters:
  resource_type: "execution"
  org_id: "<organization>"
  project_id: "<project>"
  search_term: "<pipeline name>"
```

### Step 4: Get Execution Details

```
Call MCP tool: harness_get
Parameters:
  resource_type: "execution"
  resource_id: "<execution_id>"
  org_id: "<organization>"
  project_id: "<project>"
```

### Step 5: Get Execution Logs

```
Call MCP tool: harness_get
Parameters:
  resource_type: "execution_log"
  resource_id: "<execution_id>"
  org_id: "<organization>"
  project_id: "<project>"
```

### Step 6: Get Pipeline Definition

```
Call MCP tool: harness_get
Parameters:
  resource_type: "pipeline"
  resource_id: "<pipeline_identifier>"
  org_id: "<organization>"
  project_id: "<project>"
```

## Analysis Framework

Categorize errors and provide targeted fixes:

### Build Failures
- Missing dependencies - Check package.json/requirements.txt
- Compilation errors - Review recent code changes
- Docker build failures - Check Dockerfile and base image

### Infrastructure Errors
- "No delegate available" - Check delegate status, verify tags match
- Connector failures - Rotate credentials, test connection
- Resource limits - Check cloud quotas and limits

### Configuration Errors
- "Secret not found" - Verify secret exists at correct scope (account/org/project)
- "Could not resolve expression" - Check expression syntax
- "Connector not found" - Verify connectorRef identifier

### Deployment Errors
- ImagePullBackOff - Check registry credentials and image tag
- CrashLoopBackOff - Check container logs, resource limits
- Readiness probe failed - Review probe configuration

### Timeout Errors
- Step/stage exceeded timeout - Increase timeout or optimize
- Delegate task queued too long - Scale up delegates

### Artifact Errors
- "Artifact not found" - Verify artifact path, check upstream build

## Response Format

```
## Pipeline Failure Analysis

**Pipeline:** <name>
**Execution:** <id>
**Failed At:** <timestamp>

### Failure Summary
**Stage:** <failed_stage>
**Step:** <failed_step>
**Error:** <error message>

### Root Cause
<explanation>

### Fix
**Immediate:** <specific steps>
**Prevention:** <how to avoid in future>
```

## Examples

- "Why did my build pipeline fail?" - Use `harness_diagnose` with pipeline_id
- "Debug execution abc123" - Use `harness_diagnose` with execution_id
- "Show me recent failures" - Use `harness_status` then drill into failures
- "Analyze the pipeline at https://app.harness.io/..." - Pass URL directly to `harness_diagnose`
- "Which stage is the bottleneck in my pipeline?" - Use `harness_diagnose` on a successful execution
- "Get full logs for the failed deploy step" - Use `harness_diagnose` with `include_logs: true`

## Performance Notes

- Take your time analyzing logs thoroughly. Read complete error messages and stack traces before diagnosing.
- Check all failed steps, not just the first one. Multiple failures may share a root cause or reveal a dependency chain.
- Quality of diagnosis is more important than speed. A wrong diagnosis wastes more time than a thorough one.

## Troubleshooting

### Logs Not Available
- Logs expire based on retention settings
- Very recent executions may have delayed logs
- Aborted executions may not have complete logs

### Cannot Find Execution
- Verify org/project scope
- Remove filters to see all executions
- Check RBAC permissions

### MCP Connection Issues
- Verify MCP server is running and connected
- Check API key validity
- Ensure required toolsets (pipelines, logs) are enabled