Fixing False Positives

Learn to tune Jnkn when it makes incorrect matches.

Time: 10 minutes

When to Suppress

False positives happen when Jnkn links unrelated artifacts due to similar names:

env:HOST  ←→  infra:ghost_writer    # Wrong! Just share "host" substring
env:ID    ←→  infra:user_id         # Wrong! "ID" is too generic

Strategy 1: Raise Confidence Threshold

Edit .jnkn/config.yaml:

stitching:
  min_confidence: 0.6  # Default is 0.5

Higher threshold = fewer matches = fewer false positives (but may miss real links).

Strategy 2: Add Suppressions

Suppress specific patterns that you know are wrong.

Suppress a Single Match

jnkn suppress add "env:HOST" "infra:ghost_writer" \
  --reason "Unrelated - ghost_writer is a logging service"

Suppress a Pattern

Use globs to suppress categories:

# All *_ID env vars are too generic
jnkn suppress add "env:*_ID" "infra:*" \
  --reason "ID fields are too generic for matching"

# Ignore all matches to test infrastructure  
jnkn suppress add "*" "infra:test_*" \
  --reason "Test infrastructure, not production"

List Suppressions

jnkn suppress list

ID  Source        Target         Reason                    Expires
1   env:HOST      infra:ghost_*  Unrelated services        never
2   env:*_ID      infra:*        ID fields too generic     never
3   *             infra:test_*   Test infrastructure       2024-03-01

Remove a Suppression

jnkn suppress remove 1

Test a Suppression

Check if a match would be suppressed:

jnkn suppress test env:USER_ID infra:user_service

✓ Would be SUPPRESSED by rule 2: "env:*_ID" → "infra:*"

Strategy 3: Configure Token Filtering

Some tokens are too common to be meaningful. Edit .jnkn/config.yaml:

stitching:
  blocked_tokens:
    - id
    - key
    - url
    - host
    - port
    - name

  min_token_length: 3  # Ignore tokens shorter than this

Suppressions File

Suppressions are stored in .jnkn/suppressions.yaml:

suppressions:
  - source_pattern: "env:*_ID"
    target_pattern: "infra:*"
    reason: "ID fields are too generic"
    enabled: true
    expires: null
    created_at: "2024-01-15T10:30:00Z"

  - source_pattern: "env:HOST"
    target_pattern: "infra:ghost_*"
    reason: "Unrelated services"
    enabled: true
    expires: "2024-06-01"
    created_at: "2024-01-15T10:35:00Z"

Commit suppressions to git

Suppressions should be version-controlled so the whole team benefits.

Verifying Your Fixes

After adding suppressions, re-scan:

jnkn scan --full

Check that false positives are gone:

jnkn blast env:HOST

When to NOT Suppress

Don't suppress just because a match is unexpected. Investigate first:

jnkn explain env:PAYMENT_DB_HOST infra:payment_database

If the confidence is high and the tokens genuinely overlap, the match might be correct — you may have discovered a real dependency you didn't know about.