Green Metrics Tool
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Network IO - cgroup - container

What it does

It reads the total amount of sent and received bytes from the network interface inside the assigned namespace by the cgroup of the container. More information about cgroups can be found in the Linux manual pages.

Classname

  • NetworkIoCgroupContainerProvider

Metric Name

  • network_io_cgroup_container

Input Parameters

  • args
    • -s: container-ids separated by commas
    • -i: interval in milliseconds

By default the measurement interval is 100 ms.

./metric-provider-binary -i 100 -s 7f38a4c25fb8f9d5f8651d6ed986b3658dba20d1f5fec98a1f71c141c2b48f4b,c3592e1385d63f9c7810470b12aa00f7d6f7c0e2b9981ac2bdb4371126a0660a

Output

This metric provider prints to Stdout a continuous stream of data. The format of the data is as follows:

TIMESTAMP READING CONTAINER-ID

Where:

  • TIMESTAMP: Unix timestamp, in microseconds
  • READING: The amount of memory, in bytes, used during the time interval
  • CONTAINER-ID: The container ID that this reading is for

Any errors are printed to Stderr.

How it works

The provider assumes that you have cgroups v2 enabled on your system.

It first enters the namespace via at setns systemcall of the root process of the container.

The relevant file it uses is: /proc/<PROCESS-ID>/ns/net.

After having entered the namespace the provider reads from /proc/net/dev and:

  • parses the output
  • skips all lo interfaces
  • sums up the r_bytes and t_bytes of all other interfaces
  • does NOT count dropped packets (we assume since most of the traffic is internal, that a dropped received packet shows up in another interface as sent anyway and a dropped sent packet does not attribute much to the energy consumption).

Attribution of network traffic

Currently all incoming and outgoing traffic is attributed to every container that sends or receives it.

This may lead to unexpected results when you process the results, but is a design decision.

In our Green Metrics Dashboard we simply accumulate all the network traffic of all containers and calculate CO2 emissions by applying the CO2-Formula on top.

The page Network Carbon Intensity → provides more information and discusses the advantages and disadvantages of this approach.

Network Connections - Proxy Container
Network IO - cgroup - system