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Check TCP ports (databases, caches)

Some dependencies have no HTTP endpoint to probe - databases, caches, message brokers. The tcp_check receiver opens a connection to each endpoint on an interval and reports tcpcheck.status and, on failure, tcpcheck.error.

OpenTelemetry Collector

OpenTelemetry Collector YAML

receivers:
  tcp_check:
    collection_interval: 60s
    targets:
      - endpoint: db.example.internal:5432
      - endpoint: cache.example.internal:6379

processors:
  memory_limiter:
    check_interval: 1s
    limit_percentage: 80
    spike_limit_percentage: 25
  batch:
    timeout: 5s

exporters:
  otlphttp:
    endpoint: https://your-backend:4318

service:
  pipelines:
    metrics:
      receivers: [tcp_check]
      processors: [memory_limiter, batch]
      exporters: [otlphttp]

LinkMesh

Library › Sources › TCP Port Check

Targets: ["db.example.internal:5432","cache.example.internal:6379"]
Check Interval: 60s
Timeout: 10s

What LinkMesh then pushes to the collector, under receivers:

Pushed to the collector

tcpcheck/input_src_00000501:
  collection_interval: 60s
  targets:
    - dialer:
        timeout: 10s
      endpoint: db.example.internal:5432
    - dialer:
        timeout: 10s
      endpoint: cache.example.internal:6379

The same, as an API call (see automation recipes):

API call

curl -X POST "$LINKMESH/sources" \
  -H "Authorization: Bearer $LMSAT" \
  -H "Content-Type: application/json" \
  -d '{
  "defaultConfig": {
    "collection_interval": "60s",
    "endpoints": [
      "db.example.internal:5432",
      "cache.example.internal:6379"
    ],
    "timeout": "10s"
  },
  "name": "TCP Port Check",
  "receiverType": "tcp_check"
}'

The rest of the collector config above (tcp_check, memory_limiter, batch, otlphttp) is not part of this template: in LinkMesh those are separate sources, processors and destinations on the route.

Generated from LinkMesh's template catalogue by linkmesh-server snippet-render 1.464.3, not written by hand.

Download config.yamlValidated with otelcol-contrib v0.161.0 on 2026-10-26

Complete config files, each checked with the collector's own validate command (otelcol-contrib v0.161.0). Replace https://your-backend:4318 with your own OTLP endpoint before you run it.

The gotcha

Failures are reported by error code, as a counter. In our test unreachable endpoints reported tcpcheck.status 0 and a tcpcheck.error sum with error.code network_unreachable, one per endpoint. The receiver was called tcpcheck; otelcol-contrib 0.161.0 logs that alias as deprecated in favour of tcp_check, which this config uses.

Manage this across a fleet

LinkMesh manages collector configuration across a fleet from one self-hosted control plane, so a change like this is made once rather than host by host. The first 25 Collectors are free after a no-card registration in the OpenSight Customer Portal (5 without one).

Doing this in LinkMesh: Sources

Install LinkMesh →See all snippets

Check TCP ports (databases, caches)

OpenTelemetry Collector

LinkMesh

The gotcha

Manage this across a fleet

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