Memcached (community)

Plugin: go.d.plugin Module: prometheus

Overview

Monitor Memcached in-memory key-value store metrics for efficient caching performance and management.

Metrics are gathered by periodically sending HTTP requests to Memcached exporter.

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

By default, it detects instances running on the local host by trying to connect to known ports that are allocated to exporters.

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

This collector has built-in grouping logic based on the type of metrics.

Metric	Chart	Dimension(s)	Algorithm
Gauge	for each label set	one, the metric name	absolute
Counter	for each label set	one, the metric name	incremental
Summary (quantiles)	for each label set (excluding 'quantile')	for each quantile	absolute
Summary (sum and count)	for each label set	the metric name	incremental
Histogram (buckets)	for each label set (excluding 'le')	for each bucket	incremental
Histogram (sum and count)	for each label set	the metric name	incremental

Untyped metrics (have no '# TYPE') processing:

• As Counter or Gauge depending on pattern match when 'fallback_type' is used.
• As Counter if it has suffix '_total'.
• As Summary if it has 'quantile' label.
• As Histogram if it has 'le' label.

The rest are ignored.

Alerts

There are no alerts configured by default for this integration.

Setup

Prerequisites

Install Exporter

Install Memcached exporter by following the instructions mentioned in the exporter README.

Configuration

File

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

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/prometheus.conf

Options

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

Config options

Name	Description	Default	Required
update_every	Data collection frequency.	10	no
autodetection_retry	Recheck interval in seconds. Zero means no recheck will be scheduled.	0	no
url	Server URL.		yes
selector	Time series selector (filter).		no
fallback_type	Time series selector (filter).		no
max_time_series	Global time series limit. If an endpoint returns number of time series > limit the data is not processed.	2000	no
max_time_series_per_metric	Time series per metric (metric name) limit. Metrics with number of time series > limit are skipped.	200	no
label_prefix	An optional prefix that will be added to all labels of all charts. If set, the label names will be automatically formatted as prefix_name (the prefix followed by an underscore and the original name).		no
timeout	HTTP request timeout.	10	no
username	Username for basic HTTP authentication.		no
password	Password for basic HTTP authentication.		no
proxy_url	Proxy URL.		no
proxy_username	Username for proxy basic HTTP authentication.		no
proxy_password	Password for proxy basic HTTP authentication.		no
method	HTTP request method.	GET	no
body	HTTP request body.		no
headers	HTTP request headers.		no
not_follow_redirects	Redirect handling policy. Controls whether the client follows redirects.	no	no
tls_skip_verify	Server certificate chain and hostname validation policy. Controls whether the client performs this check.	no	no
tls_ca	Certification authority that the client uses when verifying the server's certificates.		no
tls_cert	Client TLS certificate.		no
tls_key	Client TLS key.		no

selector

This option allows you to filter out unwanted time series. Only metrics matching the selector will be collected.

• Logic: (pattern1 OR pattern2) AND !(pattern3 or pattern4)
• Pattern syntax: selector.
• Option syntax:

selector:
  allow:
    - pattern1
    - pattern2
  deny:
    - pattern3
    - pattern4

fallback_type

This option allows you to process Untyped metrics as Counter or Gauge instead of ignoring them.

• Metric name pattern syntax: shell file name pattern.
• Option syntax:

fallback_type:
  counter:
    - metric_name_pattern1
    - metric_name_pattern2
  gauge:
    - metric_name_pattern3
    - metric_name_pattern4

Examples

Basic

Note: Change the port of the monitored application on which it provides metrics.

A basic example configuration.

jobs:
  - name: local
    url: http://127.0.0.1:9090/metrics

Read metrics from a file

An example configuration to read metrics from a file.

Config

# use "file://" scheme
jobs:
  - name: myapp
    url: file:///opt/metrics/myapp/metrics.txt

HTTP authentication

Note: Change the port of the monitored application on which it provides metrics.

Basic HTTP authentication.

Config

jobs:
  - name: local
    url: http://127.0.0.1:9090/metrics
    username: username
    password: password

HTTPS with self-signed certificate

Note: Change the port of the monitored application on which it provides metrics.

Do not validate server certificate chain and hostname.

Config

jobs:
  - name: local
    url: https://127.0.0.1:9090/metrics
    tls_skip_verify: yes

Multi-instance

Note: When you define multiple jobs, their names must be unique. Note: Change the port of the monitored application on which it provides metrics.

Collecting metrics from local and remote instances.

Config

jobs:
  - name: local
    url: http://127.0.0.1:9090/metrics

  - name: remote
    url: http://192.0.2.1:9090/metrics

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 prometheus 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 prometheus

Getting Logs

If you're encountering problems with the prometheus 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 prometheus

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 prometheus /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 prometheus