[steven777400]

I enjoy reading descriptions such as these that start with easily detectable problems and go into a level of debugging far beyond my skill level. Helps to illuminate some of those "unknown unknowns" that I didn't even ever consider before.

[oneplane]

I had the same feeling, but this also reinforced my view that Docker and containerization in general (often used as a scapegoat to not have to do proper configuration management) 'for the masses' is more problematic than helpful. In most cases it doesn't solve anything but does add problems that can be hard to debug. The actual 'lack' of isolation wouldn't have happened with true virtualisation, and the method of debugging here is something most people that think they need containers won't have.

To me, debugging like this is something that should be far more important to people than slinging words like Docker and NodeJS around all day. (and then mostly on Discord, or to them, the older Slack, but not IRC because that is too hard for that crowd -- totally unfounded opinion/rant)

[dasil003]

Docker didn't cause this problem, the point of the article is that Docker doesn't prevent all such problems. On the other hand it does solve a lot of packaging, dependency and environment parity problems that traditional virtualization is too heavy to accomplish.

I'm old enough to also be frustrated with buzzword driven development, and it's pretty annoying that so many believe Docker invented containerization, but don't throw the baby out with the bathwater. Containerization is an awesome tool and orthogonal to config management.

[eropple]

Traditional virtualization is "too heavy", now, for solved problems like packaging? How and why?

[omginternets]

For the reasons mentioned in the article:

- slow (re)start times

- greater resource consumption

Granted, "too heavy" is relative, but starting a few hundred VMs on a single host (assuming commodity hardware) is not going to work very well.

[oneplane]

Slow? What is slow. VMs start in 4 seconds. While a container might do it in 1 or less, 4 seconds isn't slow.

Resource consumption might be more, but it's not going to be dramatically more than a container. It's not like a container uses nothing, the management and resource constrainers take up resources too.

Containers simply solve nothing and aren't 'better' in general. Containerizing certain programs might be useful, but other than that they are being hyped by the 'shiny new thing' crowd more than it deserves. On top of that, the amount of people using it vs. the amount of people that actually need it is way more of an issue than a container vs. vm debate.

[nogox]

Did you try runV. It launches a Docker image into a micro VM in 100ms. github.com/hyperhq/runv

[user5994461]

That works just fine. It's typical in a VM farm to have hosts with a hundred VMs.

[omginternets]

>It's typical in a VM farm to have hosts with a hundred VMs.

Several things:

1. We may have a different definition of "commodity hardware", but you're missing the broader point.

2. The broader point is that VMs are significantly less resource-efficient.

3. 1 & 2 notwithstanding, you're conveniently ignoring the issue of (re)start time

4. It's fine to use VMs, but it's frankly bizarre to fight tooth-and-nail over the ridiculous notion that they should always be preferred over containers.

[eikenberry]

+1. Docker is not Docker-Swarm/Kubernetes.

[AlphaSite]

Hey, there are plenty of solutions which combine the best of both worlds; for example https://www.vmware.com/products/vsphere/integrated-container...

[icebraining]

How is that the best? You're still running a full kernel for each container, rather than sharing it.

[gaius]

But, so what? VMWare under the hood is sharing common pages between VMs, and a kernel that isn't doing anything isn't consuming any CPU, so why not?

[icebraining]

Nope, common pages are no longer shared between VMs, because it was demonstrated that was a bad idea, security-wise:

upcoming ESXi Update releases will no longer enable TPS between Virtual Machines by default

https://kb.vmware.com/selfservice/microsites/search.do?langu...

[bogomipz]

>"I had the same feeling, but this also reinforced my view that Docker and containerization in general (often used as a scapegoat to not have to do proper configuration management) 'for the masses' is more problematic than helpful. In most cases it doesn't solve anything but does add problems that can be hard to debug."

The issue described in this post has nothing to do with "config management vs containers." Its' odd that this article would have "reinforced" that view. How would configuration management have prevented a noisy neighbor?

From the summary:

"The core lesson of this story: just because you are using containers and you get the impression that your applications are perfectly virtualized and isolated, don’t assume the kernel is fully isolating every underlying resource at a container granularity."

and

"Luckily, the solution is there and rather simple: make sure to deeply monitor all your applications."

That's nothing to do with any "configuration management vs containers" argument and everything to do with proper metrics collection and monitoring, which should be part of every "operational readiness" checklist whether Docker is used or not.

Lastly saying that Docker "In most cases it doesn't solve anything" is an absurd statement. Do you believe that virtualization does't solve any problems? If so why do you imagine the Linux kernel supports it?

[gaius]

just because you are using containers and you get the impression that your applications are perfectly virtualized and isolated

Anyone who believes in the first place this shouldn't be running production systems...

[bogomipz]

Your comment contains two sentence fragments, neither of which is coherent.

[gaius]

Seems perfectly straightforward. If you believe containers give you the level of isolation that VMs would, then you have fundamental misunderstandings of the technology which in a sane organisation would preclude you from operating important systems.

[bogomipz]

No your comment is anything but straightforward. In fact its grammatically incorrect to the point of being incoherent and incomprehensible. Maybe you should re-read what you wrote? It's bizarre to think that anyone would read that and think it was articulate.

Nowhere did I state that or even remotely suggest that containers give you the level of isolation that VMs would. My comment was refuting the OPs suggestion that "configuration management" was relevant to the article. Maybe you should go back and re-read the thread.

[user5994461]

sysdig is a monitoring system for docker that sells for $25 per month per host.

Part of the debugging method has to do with "let's show our product".

[daddykotex]

I had the exact same feeling.

Well written OP.