Docker stats questions

Docker Engine General
1

@crosbymichael thanks heaps for adding docker stats. I had some questions about the CLI side of things.

Are there any plans for a version that can be consumed out of TTY, eg just give you a single line and exit?

Are there any plans to make docker stats work without any params and simply display full stats for all containers?

2

As for the CLI consuming one line and exiting I don’t have any plans for it. It was meant to be a simple way to quickly view stats for some containers, if you need more information or better control, hitting the API is your best bet because it provides much more information.

A single API endpoint for all container could be cool. If you feel like trying to contribute this go ahead :wink:

3

I definitely think having docker stats by its lonesome work in a similar way to htop would be super awesome, even if there are no plans for a non refreshing cli version.

I will have a look at doing a docker PR but it may take a bit, will consume the API for now.

Thanks heaps, it is a very useful feature.

4

Quick one,

In the context of multiple CPUs and processes, what does the CPU percent mean? Can it go above 100%?

(note this is possible even in a single app per container setting, for example postgres will fork per connection)

5

Yes, it can go over 100% if multiple cores are used.

6

thanks, when I was looking at the PR

https://github.com/docker/docker/blob/master/api/client/commands.go#L2758-L2771

It seems to be scaling it according to the number of CPUs its reporting, I wonder if this accounts for situations where the container is only allowed to work on 4/8 cpus

I did implement monitoring at:

The API seemed pretty straight forward though deciphering the meaning of the numbers was a bit rough cause I had to dig in to the source to figure it out, API docks are a bit thin.

Hardest thing was consuming the API in a non streaming way, it forced a pretty rough pattern and I worry that if there is a bug somewhere I am going to leak connections. I think a non-streaming option would be very helpful.