Remove hardcoded trigger limit from Monitor data class and make number of triggers per monitor configurable

[manaswini1920]

Description

Remove the hardcoded trigger count limit (MONITOR_MAX_TRIGGERS = 10) from the Monitor data class init block. Trigger count validation is moved to the alerting plugin, where it can be configured via a dynamic c
luster setting (plugins.alerting.monitor.max_triggers).

Companion alerting PR: opensearch-project/alerting#2036

Resolves opensearch-project/alerting#468

Related Issues

Resolves
opensearch-project/alerting#1828
https://github.com/opensearch-project/alerting#468

Testing

• Updated existing test to verify Monitor allows >10 triggers at the model level
• End-to-end tested with alerting plugin changes on a local cluster:
  • Default limit (10): 11 triggers rejected
  • Limit set to 20: 11 triggers accepted
  • Limit set to 5: 6 triggers rejected

Test 1 — Default limit (10), 11 triggers rejected:

# Generate 11 triggers
TRIGGERS=""
for i in $(seq 1 11); do
  if [ -n "$TRIGGERS" ]; then TRIGGERS="$TRIGGERS,"; fi
  TRIGGERS="$TRIGGERS{\"name\":\"trigger-$i\",\"severity\":\"1\",\"condition\":{\"script\":{\"source\":\"return true\",\"lang\":\"painless\"}},\"actions\":[]}"
done

curl -XPOST 'localhost:9200/_plugins/_alerting/monitors' -H 'Content-Type: application/json' -d "{
  \"type\": \"monitor\",
  \"name\": \"test-11-triggers\",
  \"monitor_type\": \"query_level_monitor\",
  \"enabled\": false,
  \"schedule\": {\"period\": {\"interval\": 10, \"unit\": \"MINUTES\"}},
  \"inputs\": [{\"search\": {\"indices\": [\"*\"], \"query\": {\"query\": {\"match_all\": {}}}}}],
  \"triggers\": [$TRIGGERS]
}"

# Response:
# { "error": { "reason": "Monitors can only support up to 10 triggers." }, "status": 400 }

est 2 — Increase limit to 20, 11 triggers accepted:

# Update setting
curl -XPUT 'localhost:9200/_cluster/settings' -H 'Content-Type: application/json' -d '{
  "persistent": {"plugins.alerting.monitor.max_triggers": 20}
}'
# Response: { "acknowledged": true }

# Same 11 triggers payload as above
# Response: 200 OK — monitor created

# Verify triggers stored
curl -s 'localhost:9200/_plugins/_alerting/monitors/<monitor_id>' | python3 -c "import sys,json; d=json.load(sys.stdin); print(f'Trigger count: {len(d[\"monitor\"][\"triggers\"])}')"
# Output: Trigger count: 11

Test 3 — Decrease limit to 5, 6 triggers rejected:

# Update setting
curl -XPUT 'localhost:9200/_cluster/settings' -H 'Content-Type: application/json' -d '{
  "persistent": {"plugins.alerting.monitor.max_triggers": 5}
}'
# Response: { "acknowledged": true }

# Generate 6 triggers
TRIGGERS=""
for i in $(seq 1 6); do
  if [ -n "$TRIGGERS" ]; then TRIGGERS="$TRIGGERS,"; fi
  TRIGGERS="$TRIGGERS{\"name\":\"trigger-$i\",\"severity\":\"1\",\"condition\":{\"script\":{\"source\":\"return true\",\"lang\":\"painless\"}},\"actions\":[]}"
done

curl -XPOST 'localhost:9200/_plugins/_alerting/monitors' -H 'Content-Type: application/json' -d "{
  \"type\": \"monitor\",
  \"name\": \"test-6-triggers\",
  \"monitor_type\": \"query_level_monitor\",
  \"enabled\": false,
  \"schedule\": {\"period\": {\"interval\": 10, \"unit\": \"MINUTES\"}},
  \"inputs\": [{\"search\": {\"indices\": [\"*\"], \"query\": {\"query\": {\"match_all\": {}}}}}],
  \"triggers\": [$TRIGGERS]
}"

# Response:
# { "error": { "reason": "Monitors can only support up to 5 triggers." }, "status": 400 }

Check List

• [ X] New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• [ X] Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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