Memcached

Auto-Detection

Health Check

Built-in Metrics

Memcached is a high-performance, distributed in-memory caching system.

Auto-Detection

Glouton detects Memcached by its process and listening port (default: 11211).

If auto-detected parameters are incorrect, override them manually:

Linux

sudo tee /etc/glouton/conf.d/99-memcached.conf > /dev/null << 'EOF'
service:
  # For a Memcached running outside a container
  - type: "memcached"
    address: "127.0.0.1"
    port: 11211

  # For an additional Memcached running outside a container
  - type: "memcached"
    instance: "NAME_ASSOCIATED_WITH_YOUR_ADDITIONAL_SERVICE"
    address: "127.0.0.1"
    port: 11212

  # For a Memcached running in a Docker container
  - type: "memcached"
    instance: "CONTAINER_NAME"
    address: "172.17.0.2"
    port: 11211
EOF

Windows

Create or edit C:\ProgramData\glouton\conf.d\99-memcached.conf:

service:
  # For a Memcached running outside a container
  - type: "memcached"
    address: "127.0.0.1"
    port: 11211

  # For an additional Memcached running outside a container
  - type: "memcached"
    instance: "NAME_ASSOCIATED_WITH_YOUR_ADDITIONAL_SERVICE"
    address: "127.0.0.1"
    port: 11212

  # For a Memcached running in a Docker container
  - type: "memcached"
    instance: "CONTAINER_NAME"
    address: "172.17.0.2"
    port: 11211

Glouton automatically detects configuration changes.

Service Check

Glouton performs a Memcached protocol check on the configured port to verify that the server is responding.

Built-in Metrics

Metric	Description
service_status	Status of Memcached
memcached_command_get	Number of get requests per second
memcached_command_set	Number of set requests per second
memcached_connections_current	Number of client connections to Memcached
memcached_items_current	Current number of items stored
memcached_octets_rx	Network traffic received by Memcached in bytes per second
memcached_octets_tx	Network traffic sent by Memcached in bytes per second
memcached_ops_cas_hits	Number of successful CAS (Check-And-Set) requests per second
memcached_ops_cas_misses	Number of CAS requests against missing keys per second
memcached_ops_decr_hits	Number of successful decrement requests per second
memcached_ops_decr_misses	Number of decrement requests against missing keys per second
memcached_ops_delete_hits	Number of successful delete requests per second
memcached_ops_delete_misses	Number of delete requests against missing keys per second
memcached_ops_evictions	Number of items evicted to free memory for new items per second
memcached_ops_get_hits	Number of successful get requests per second
memcached_ops_get_misses	Number of get requests against missing keys per second
memcached_ops_incr_hits	Number of successful increment requests per second
memcached_ops_incr_misses	Number of increment requests against missing keys per second
memcached_ops_touch_hits	Number of successful touch requests per second
memcached_ops_touch_misses	Number of touch requests against missing keys per second
memcached_percent_hitratio	Hit ratio of get requests in percent
memcached_ps_count_threads	Number of worker threads
memcached_uptime	Time since Memcached server start in seconds

Monitoring Troubleshooting

See Troubleshoot a Service Check or Missing Metrics for what applies to every service: finding the address and port Glouton really uses, what each check message means, and how to read the collection error — which does not appear in the agent logs at the default level.

The Service Check is not OK

Glouton sends version on the Memcached port and expects a VERSION answer:

Status text	Cause	Fix
TCP port 11211, Connection refused	Memcached listens on another port or address, or only on a UNIX socket	Set address and port; a socket-only Memcached cannot be checked
TCP port 11211, unexpected response "..."	Something that is not Memcached answers on that port, or SASL authentication is required	Check what listens there; Glouton cannot authenticate to Memcached
TCP port N, connection timed out after 10 seconds	A firewall drops the packets	Open the port for the agent

Metrics are Missing

Metrics come from the stats command on the same port, sent without authentication — Glouton has no way to authenticate to Memcached. A check that passes means version was answered, so the remaining causes are a server that answers version but refuses stats, or a plan that does not include the built-in metrics: those require the Professional plan, while the availability check is available on every plan. The error Memcached returned is in scrape-loop-active.json, under memcached input.

printf 'stats\r\n' | nc -w 2 127.0.0.1 11211 | head -5