4 ms·

Could you elaborate on the instability concerns? What kind of workload are you running on containers?

cookiecaper 10y ago
Sure. Here's one example that I've dealt with in the last week. We have a server that receives the logs from our kubernetes cluster via fluentd and parses/transforms them before shipping them out to a hosted log search backend thingy. This host has 5 Docker containers running fluentd receivers. This works OK most of the time, but in some cases, particularly cases when the log volume is high and/or when a bug causes excessive writes to stdout/stderr (the container does have the appropriate log driver size setting configured at the Docker level), the container will cease to function. It cannot be accessed or controlled. docker-swarm will try but it cannot manipulate it. You can force kill the container in Docker, but then you can't bring the service/container back up because something doesn't get cleaned up right on Docker's insides. You have to restart the Docker daemon and then restart all of the containers with docker-swarm to get back to a good state. Due to https://github.com/moby/moby/issues/8795 https://github.com/moby/moby/issues/8795 , you also must manually run `conntrack -F` after restarting the Docker daemon (something that took some substantial debug/troubleshooting time to figure out). We've had this happen on that server 3 times over the last month. That's ONE example. There are many more! Containers are a VC-fueled fad. There are huge labor/complexity costs associated and relatively small gains. You're entering a sub-world with a bunch of layers to reimplement things for a containerized world, whereas the standard solutions have existed and worked well for many years, and the only reason not to use them is that the container platform doesn't accommodate them. And what's the benefit? You get to run every application as a 120MB Docker image? You get to pay for space in a Docker Registry? Ostensibly you can fit a lot more applications onto a single machine (and correspondingly cut the ridiculous cloud costs that many companies pay because it's too hard to hire a couple of hardware jockeys or rent a server from a local colo), but you can also do this just fine without Docker. Google is pushing containers hard because it's part of their strategy to challenge Amazon Cloud, not because it benefits the consumer.
- andrewguenther 10y ago
  So your problem is with Docker, not containers as a concept.
  - cookiecaper 10y ago
    Yeah, kind of. The complexity of the current iteration is not wholly the fault of Docker, though I'm sure some of the utilities had to increase complexity to work well with Docker (k8s just barely got support for other container platforms). This was a story about an annoyance/bug/issue with Docker, but I have annoyances with other things too. Some people did not know how to do any server management before kubernetes became a big deal, so they think kubernetes is the only way to do it. For the rest of us, I don't think there's a lot of value brought by this ecosystem.
- eikenberry 10y ago
  I think you are suffering a bit from the over-engineering of Kubernetes and Docker and throwing the baby out with the bath water. Containers in general are great for simplifying deployment, development and testing. We use docker currently and it works great, but we are using just docker and using it only as a way to simplify the above. We are deploying 1 application to 1 system (EC2 via ASG). There is also nothing keeping you using Docker for containers. LXC also works great and it has no runtime, so you have none of the stability issues you can get with Docker. Though I must say Docker has improved a lot and I think it will stabilize and _it_ won't be an issue (not as sure about Kubernetes).
  - cookiecaper 10y ago
    Sure, I agree that both Docker and k8s (at some level, k8s probably had to have a lot of that complexity to interface with Docker) are overengineered, and that there are better containerization processes/runtimes. But I still don't think containers are what most people want. People need/want ultra-lightweight VMs with atomized state. NixOS looks promising but I haven't used it yet. It seems to give you a way to deterministically reason about your system without just shipping around blobs of the whole userland. You can also approximate this on other systems with a good scripting toolkit like Ansible.

Sure. Here's one example that I've dealt with in the last week. We have a server that receives the logs from our kubernetes cluster via fluentd and parses/transforms them before shipping them out to a hosted log search backend thingy. This host has 5 Docker containers running fluentd receivers. This works OK most of the time, but in some cases, particularly cases when the log volume is high and/or when a bug causes excessive writes to stdout/stderr (the container does have the appropriate log driver size setting configured at the Docker level), the container will cease to function. It cannot be accessed or controlled. docker-swarm will try but it cannot manipulate it. You can force kill the container in Docker, but then you can't bring the service/container back up because something doesn't get cleaned up right on Docker's insides. You have to restart the Docker daemon and then restart all of the containers with docker-swarm to get back to a good state. Due to https://github.com/moby/moby/issues/8795 https://github.com/moby/moby/issues/8795 , you also must manually run `conntrack -F` after restarting the Docker daemon (something that took some substantial debug/troubleshooting time to figure out). We've had this happen on that server 3 times over the last month. That's ONE example. There are many more! Containers are a VC-fueled fad. There are huge labor/complexity costs associated and relatively small gains. You're entering a sub-world with a bunch of layers to reimplement things for a containerized world, whereas the standard solutions have existed and worked well for many years, and the only reason not to use them is that the container platform doesn't accommodate them. And what's the benefit? You get to run every application as a 120MB Docker image? You get to pay for space in a Docker Registry? Ostensibly you can fit a lot more applications onto a single machine (and correspondingly cut the ridiculous cloud costs that many companies pay because it's too hard to hire a couple of hardware jockeys or rent a server from a local colo), but you can also do this just fine without Docker. Google is pushing containers hard because it's part of their strategy to challenge Amazon Cloud, not because it benefits the consumer.

andrewguenther 10y ago
So your problem is with Docker, not containers as a concept.
- cookiecaper 10y ago
  Yeah, kind of. The complexity of the current iteration is not wholly the fault of Docker, though I'm sure some of the utilities had to increase complexity to work well with Docker (k8s just barely got support for other container platforms). This was a story about an annoyance/bug/issue with Docker, but I have annoyances with other things too. Some people did not know how to do any server management before kubernetes became a big deal, so they think kubernetes is the only way to do it. For the rest of us, I don't think there's a lot of value brought by this ecosystem.
eikenberry 10y ago
I think you are suffering a bit from the over-engineering of Kubernetes and Docker and throwing the baby out with the bath water. Containers in general are great for simplifying deployment, development and testing. We use docker currently and it works great, but we are using just docker and using it only as a way to simplify the above. We are deploying 1 application to 1 system (EC2 via ASG). There is also nothing keeping you using Docker for containers. LXC also works great and it has no runtime, so you have none of the stability issues you can get with Docker. Though I must say Docker has improved a lot and I think it will stabilize and _it_ won't be an issue (not as sure about Kubernetes).
- cookiecaper 10y ago
  Sure, I agree that both Docker and k8s (at some level, k8s probably had to have a lot of that complexity to interface with Docker) are overengineered, and that there are better containerization processes/runtimes. But I still don't think containers are what most people want. People need/want ultra-lightweight VMs with atomized state. NixOS looks promising but I haven't used it yet. It seems to give you a way to deterministically reason about your system without just shipping around blobs of the whole userland. You can also approximate this on other systems with a good scripting toolkit like Ansible.