Memcached

Plugin: go.d.plugin Module: memcached

Overview

Monitor Memcached metrics for proficient in-memory key-value store operations. Track cache hits, misses, and memory usage for efficient data caching.

It reads the server's response to the stats command.

This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

Default Behavior

Auto-Detection

If no configuration is given, collector will attempt to connect to memcached instance on 127.0.0.1:11211 address.

Limits

The default configuration for this integration does not impose any limits on data collection.

Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

Metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

Per Memcached instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

Metric	Dimensions	Unit
memcached.cache	available, used	MiB
memcached.net	in, out	kilobits/s
memcached.connections	current, rejected, total	connections/s
memcached.items	current, total	items
memcached.evicted_reclaimed	reclaimed, evicted	items
memcached.get	hints, misses	requests
memcached.get_rate	rate	requests/s
memcached.set_rate	rate	requests/s
memcached.delete	hits, misses	requests
memcached.cas	hits, misses, bad value	requests
memcached.increment	hits, misses	requests
memcached.decrement	hits, misses	requests
memcached.touch	hits, misses	requests
memcached.touch_rate	rate	requests/s

Alerts

The following alerts are available:

Alert name	On metric	Description
memcached_cache_memory_usage	memcached.cache	cache memory utilization
memcached_cache_fill_rate	memcached.cache	average rate the cache fills up (positive), or frees up (negative) space over the last hour
memcached_out_of_cache_space_time	memcached.cache	estimated time the cache will run out of space if the system continues to add data at the same rate as the past hour

Setup

You can configure the memcached collector in two ways:

Method	Best for	How to
UI	Fast setup without editing files	Go to Nodes → Configure this node → Collectors → Jobs, search for memcached, then click + to add a job.
File	If you prefer configuring via file, or need to automate deployments (e.g., with Ansible)	Edit go.d/memcached.conf and add a job.

important

UI configuration requires paid Netdata Cloud plan.

Prerequisites

UNIX socket access

If you are connecting to Memcached via its UNIX socket, ensure that the netdata user has permission to access it. You can do this by:

1. Adding the netdata user to the memcache group.

   sudo gpasswd -a netdata memcache

2. Configuring the socket permissions in /etc/memcached.conf so the group has access (e.g. -a 770).

Note: You may need to restart Memcached after making these changes for them to take effect.

Configuration

Options

The following options can be defined globally: update_every, autodetection_retry.

Config options

Group	Option	Description	Default	Required
Collection	update_every	Data collection interval (seconds).	1	no
	autodetection_retry	Autodetection retry interval (seconds). Set 0 to disable.	0	no
Target	address	Memcached server address (IP:PORT).	127.0.0.1:11211	yes
	timeout	Connection, read, write, and name resolution timeout (seconds).	1	no
Virtual Node	vnode	Associates this data collection job with a Virtual Node.		no

via UI

Configure the memcached collector from the Netdata web interface:

1. Go to Nodes.
2. Select the node where you want the memcached data-collection job to run and click the ⚙ (Configure this node). That node will run the data collection.
3. The Collectors → Jobs view opens by default.
4. In the Search box, type memcached (or scroll the list) to locate the memcached collector.
5. Click the + next to the memcached collector to add a new job.
6. Fill in the job fields, then click Test to verify the configuration and Submit to save.
   • Test runs the job with the provided settings and shows whether data can be collected.
   • If it fails, an error message appears with details (for example, connection refused, timeout, or command execution errors), so you can adjust and retest.

via File

The configuration file name for this integration is go.d/memcached.conf.

The file format is YAML. Generally, the structure is:

update_every: 1
autodetection_retry: 0
jobs:
  - name: some_name1
  - name: some_name2

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/memcached.conf

Examples

Basic

A basic example configuration.

Config

jobs:
  - name: local
    address: 127.0.0.1:11211

Multi-instance

Note: When you define multiple jobs, their names must be unique.

Collecting metrics from local and remote instances.

Config

jobs:
  - name: local
    address: 127.0.0.1:11211

  - name: remote
    address: 203.0.113.0:11211

Troubleshooting

Debug Mode

Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the memcached collector, run the go.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn't working.

• Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that's not the case on your system, open netdata.conf and look for the plugins setting under [directories].

  cd /usr/libexec/netdata/plugins.d/

• Switch to the netdata user.

  sudo -u netdata -s

• Run the go.d.plugin to debug the collector:

  ./go.d.plugin -d -m memcached

  To debug a specific job:

  ./go.d.plugin -d -m memcached -j jobName

Getting Logs

If you're encountering problems with the memcached collector, follow these steps to retrieve logs and identify potential issues:

• Run the command specific to your system (systemd, non-systemd, or Docker container).
• Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.

System with systemd

Use the following command to view logs generated since the last Netdata service restart:

journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep memcached

System without systemd

Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector's name:

grep memcached /var/log/netdata/collector.log

Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.

Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

docker logs netdata 2>&1 | grep memcached