Memcached

The Memcached integration primarily collects cache-usage metrics, such as the number of items in a cache, the number of evictions, and the number of bytes stored. It also collects general performance metrics for CPU usage and network throughput.

For more information about Memcached, see the Memcached documentation.

Prerequisites

To collect Memcached telemetry, you must install the Ops Agent:

For metrics, install version 2.8.0 or higher.
For logs, install version 2.15.0 or higher.

This integration supports Memcached version 1.6.

Configure the Ops Agent for Memcached

Following the guide to Configure the Ops Agent, add the required elements to collect telemetry from Memcached instances, and restart the agent.

Example configuration

The following commands create the configuration to collect and ingest telemetry for Memcached:

set -e

# Check if the file exists
if [ ! -f /etc/google-cloud-ops-agent/config.yaml ]; then
  # Create the file if it doesn't exist.
  sudo mkdir -p /etc/google-cloud-ops-agent
  sudo touch /etc/google-cloud-ops-agent/config.yaml
fi

# Create a back up of the existing file so existing configurations are not lost.
sudo cp /etc/google-cloud-ops-agent/config.yaml /etc/google-cloud-ops-agent/config.yaml.bak

# Configure the Ops Agent.
sudo tee /etc/google-cloud-ops-agent/config.yaml > /dev/null << EOF
metrics:
  receivers:
    memcached:
      type: memcached
  service:
    pipelines:
      memcached:
        receivers:
          - memcached
EOF

For these changes to take effect, you must restart the Ops Agent:

Linux

To restart the agent, run the following command on your instance:
```
sudo systemctl restart google-cloud-ops-agent
```
To confirm that the agent restarted, run the following command and verify that the components "Metrics Agent" and "Logging Agent" started:
```
sudo systemctl status "google-cloud-ops-agent*"
```

Windows

Connect to your instance using RDP or a similar tool and login to Windows.
Open a PowerShell terminal with administrator privileges by right-clicking the PowerShell icon and selecting Run as Administrator
To restart the agent, run the following PowerShell command:
```
Restart-Service google-cloud-ops-agent -Force
```
To confirm that the agent restarted, run the following command and verify that the components "Metrics Agent" and "Logging Agent" started:
```
Get-Service google-cloud-ops-agent*
```

Collect logs

Memcached writes logs to syslog, which is captured by the Ops Agent by default. No additional user configuration is required.

Configure metrics collection

To ingest metrics from Memcached, you must create a receiver for the metrics that Memcached produces and then create a pipeline for the new receiver.

This receiver does not support the use of multiple instances in the configuration, for example, to monitor multiple endpoints. All such instances write to the same time series, and Cloud Monitoring has no way to distinguish among them.

To configure a receiver for your memcached metrics, specify the following fields:

Field	Default	Description
`collection_interval`	`60s`	A time duration value, such as `30s` or `5m`.
`endpoint`	`localhost:3306`	The URL, or Unix socket file path, for your Memcached server.
`type`		This value must be `memcached`.

What is monitored

The following table provides the list of metrics that the Ops Agent collects from the Memcached instance.

Metric type
Kind, Type Monitored resources	Labels
`workload.googleapis.com/memcached.bytes`
`GAUGE`, `INT64` gce_instance
`workload.googleapis.com/memcached.commands`
`CUMULATIVE`, `INT64` gce_instance	`command`
`workload.googleapis.com/memcached.connections.current`
`GAUGE`, `INT64` gce_instance
`workload.googleapis.com/memcached.connections.total`
`CUMULATIVE`, `INT64` gce_instance
`workload.googleapis.com/memcached.cpu.usage`
`CUMULATIVE`, `DOUBLE` gce_instance	`state`
`workload.googleapis.com/memcached.current_items`
`GAUGE`, `INT64` gce_instance
`workload.googleapis.com/memcached.evictions`
`CUMULATIVE`, `INT64` gce_instance
`workload.googleapis.com/memcached.network`
`CUMULATIVE`, `INT64` gce_instance	`direction`
`workload.googleapis.com/memcached.operations`
`CUMULATIVE`, `INT64` gce_instance	`operation` `type`
`workload.googleapis.com/memcached.threads`
`GAUGE`, `INT64` gce_instance

Verify the configuration

This section describes how to verify that you correctly configured the Memcached receiver. It might take one or two minutes for the Ops Agent to begin collecting telemetry.

To verify that Memcached logs are being sent to Cloud Logging, do the following:

In the Google Cloud console, go to the Logs Explorer page:
Go to Logs Explorer

If you use the search bar to find this page, then select the result whose subheading is Logging.

Enter the following query in the editor, and then click Run query:

resource.type="gce_instance"
log_id("syslog")
jsonPayload.message~=' (systemd-memcached-wrapper|memcached)([[0-9]+])*:'

To verify that Memcached metrics are being sent to Cloud Monitoring, do the following:

In the Google Cloud console, go to the Metrics explorer page:
Go to Metrics explorer

If you use the search bar to find this page, then select the result whose subheading is Monitoring.
In the toolbar of the query-builder pane, select the button whose name is either MQL or PromQL.
Verify that MQL is selected in the Language toggle. The language toggle is in the same toolbar that lets you format your query.

Enter the following query in the editor, and then click Run query:

fetch gce_instance
| metric 'workload.googleapis.com/memcached.bytes'
| every 1m

View dashboard

To view your Memcached metrics, you must have a chart or dashboard configured. The Memcached integration includes one or more dashboards for you. Any dashboards are automatically installed after you configure the integration and the Ops Agent has begun collecting metric data.

You can also view static previews of dashboards without installing the integration.

To view an installed dashboard, do the following:

In the Google Cloud console, go to the Dashboards page:
Go to Dashboards

If you use the search bar to find this page, then select the result whose subheading is Monitoring.
Select the Dashboard List tab, and then choose the Integrations category.
Click the name of the dashboard you want to view.

If you have configured an integration but the dashboard has not been installed, then check that the Ops Agent is running. When there is no metric data for a chart in the dashboard, installation of the dashboard fails. After the Ops Agent begins collecting metrics, the dashboard is installed for you.

To view a static preview of the dashboard, do the following:

In the Google Cloud console, go to the Integrations page:
Go to Integrations

If you use the search bar to find this page, then select the result whose subheading is Monitoring.
Click the Compute Engine deployment-platform filter.
Locate the entry for Memcached and click View Details.
Select the Dashboards tab to see a static preview. If the dashboard is installed, then you can navigate to it by clicking View dashboard.

For more information about dashboards in Cloud Monitoring, see Dashboards and charts.

For more information about using the Integrations page, see Manage integrations.

Install alerting policies

Alerting policies instruct Cloud Monitoring to notify you when specified conditions occur. The Memcached integration includes one or more alerting policies for you to use. You can view and install these alerting policies from the Integrations page in Monitoring.

To view the descriptions of available alerting policies and install them, do the following:

In the Google Cloud console, go to the Integrations page:
Go to Integrations

If you use the search bar to find this page, then select the result whose subheading is Monitoring.
Locate the entry for Memcached and click View Details.
Select the Alerts tab. This tab provides descriptions of available alerting policies and provides an interface for installing them.
Install alerting policies. Alerting policies need to know where to send notifications that the alert has been triggered, so they require information from you for installation. To install alerting policies, do the following:
1. From the list of available alerting policies, select those that you want to install.
2. In the Configure notifications section, select one or more notification channels. You have the option to disable the use of notification channels, but if you do, then your alerting policies fire silently. You can check their status in Monitoring, but you receive no notifications.
  
  For more information about notification channels, see Manage notification channels.
3. Click Create Policies.

For more information about alerting policies in Cloud Monitoring, see Introduction to alerting.