The TCP RTT check reports on roundtrip times between the host the agent is running on and any host it is communicating with. This check is passive and will only report RTT times for packets being sent and received from outside the check. The check itself will not send any packets.
This check is only shipped in the 64-bit DEB and RPM Datadog Agent v5 packages. The check is currently not available with Datadog Agent v6.
Follow the instructions below to install and configure this check for an Agent running on a host. For containerized environments, see the Autodiscovery Integration Templates for guidance on applying these instructions.
The TCP RTT check-also known as go-metro-is packaged with the Agent, but requires additional system libraries. The check uses timestamps provided by the PCAP library to compute the time between any outgoing packet and the corresponding TCP acknowledgement. As such, PCAP must be installed and configured.
Debian-based systems should use one of the following:
sudo apt-get install libcap sudo apt-get install libcap2-bin
Redhat-based systems should use one of these:
sudo yum install libcap sudo yum install compat-libcap1
Finally, configure PCAP:
sudo setcap cap_net_raw+ep /opt/datadog-agent/bin/go-metro
go-metro.yaml file in your agent’s
conf.d directory. See the sample go-metro.yaml for all available configuration options.
The following is an example file that will show the TCP RTT times for app.datadoghq.com and 192.168.0.22:
init_config: snaplen: 512 idle_ttl: 300 exp_ttl: 60 statsd_ip: 127.0.0.1 statsd_port: 8125 log_to_file: true log_level: info instances: - interface: eth0 tags: - env:prod ips: - 188.8.131.52 hosts: - app.datadoghq.com
NOTE: for go-metro to run unprivileged, you will have to set CAP_NET_RAW capabilities on the binary:
# Install required libraries $ sudo apt-get install libcap # debian $ sudo apt-get install libcap2-bin # debian alternative $ sudo yum install libcap # redhat $ sudo yum install compat-libcap1 # redhat alternative # Set capabilities $ sudo setcap cap_net_raw+ep /opt/datadog-agent/bin/go-metro
Because of different package names for different distros, if the instructions above
don’t work for you, please issue an
apt-cache search libcap or
yum search libcap and you
should get a shortlist of packages that might provide the binary. Feel free to reach out
should you require assistance.
Also, please note that go-metro logs to its own file - found in
Additionally, go-metro runs standalone so it will NOT currently appear on the Agent’s info page.
Finally, because the go-metro binary is only bundled with the 64-bit RPM and DEB distributions of the Datadog Agent, it is only available in those packaged versions (i.e. go-metro is currently unavailable with the source install or the 32-bit packages).
To validate that the check is running correctly, you should see
system.net.tcp.rtt metrics showing in the Datadog interface. Also, if you Run the Agent’s
status subcommand, you should see something similar to the following:
datadog-agent.service - "Datadog Agent" Loaded: loaded (/lib/...datadog-agent.service; enabled; vendor preset: enabled) Active: active (running) since Thu 2016-03-31 20:35:27 UTC; 42min ago Process: 10016 ExecStop=/opt/.../supervisorctl -c /etc/dd-....conf shutdown (code=exited, status=0/SUCCESS) Process: 10021 ExecStart=/opt/.../start_agent.sh (code=exited, status=0/SUCCESS) Main PID: 10025 (supervisord) CGroup: /system.slice/datadog-agent.service |_10025 /opt/datadog-...python /opt/datadog-agent/bin/supervisord -c /etc/dd-agent/supervisor.conf |_10043 /opt/datadog-...python /opt/datadog-agent/agent/dogstatsd.py --use-local-forwarder |_10044 /opt/datadog-agent/bin/go-metro -cfg=/etc/dd-agent/conf.d/go-metro.yaml |_10046 /opt/datadog-.../python /opt/datadog-agent/agent/ddagent.py |_10047 /opt/datadog-.../python /opt/datadog-agent/agent/agent.py foreground --use-local-forwarder
If the TCP RTT check has started you should see something similar to the go-metro line above.
This is a passive check, so unless there are packets actively being sent to the hosts mentioned in the yaml file, the metrics are not reported.
|The TCP round trip time. Available since Agent v5.7.0.|
Shown as millisecond
|The average TCP round trip time as typically computed by the TCP stack. Available since Agent v5.7.0.|
Shown as millisecond
|The TCP round trip time jitter. Available since Agent v5.7.0.|
Shown as millisecond
The Go-metro check does not include any events.
The Go-metro check does not include any service checks.
Need help? Contact Datadog support.