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 here.

Classname

  • NetworkIoCgroupContainerProvider

Metric Name

  • network_io_cgroup_container

Input Parameters

  • args
    • -s: container-ids seperated 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 then apply the CO2-Formula on top.

This however assumes that all traffic is with external services. If your containers are however only communicating with each other and are in production all on one machine, this number will not represent the real CO2 emissions, but is rather greatly overstating them.

This design decision was made cause we cannot know during benchmarking how your containers would be orchestrated in production. They can very well be all on one machine (which would have zero network emissions), but they also could be distributed in an internal network of a datacenter (which would have only marginal network CO2 emissions) or really distributed globally (which would then have the maximum of CO2 emissions).

Since our reporters should give you an optimization baseline we opted for the worst-case scenario to report in our Dashboard.

When processing the metrics you own you may well use a different approach given your knowledge of the network topology.

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