Code change:
<!-- This form is for bug reports and feature requests ONLY! If you're looking for help check and the . --BUG REPORT: What happened: I'm running a simple Kubernetes cluster with master and one node. All basic PODs are deploying successfully (ie. weave-net) but when I try to deploy GlusterFS as a POD - container creation fails with error: This is a result of failing to perform from docker file. The weird part is that if I run this image directly on node through docker it runs smoothly. What you expected to happen: I'd expect to be able to deploy GlusterFS through Kubernetess properly. How to reproduce it (as minimally and precisely as possible): Setup minimal cluster and try to deploy the follwing POD Anything else we need to know?: Environment: Kubernetes version (use ):Cloud provider or hardware configuration**: virtualbox OS (e.g. from /etc/os-release):Kernel (e.g. ):Docker versionInstall tools: vagrant Others:
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/sig node
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One update - I can deploy this POD with no problems on version of k8s.
I am hitting the same bug on a freshly installed k8s cluster running on installed via kubeadm plus weave-net with a currently unsupported docker version. For me, downgrading to a supported docker version helped to resolve this issue (v1.12):
- Thanks for the info! - Well we can confirm that kubernetes is not working properly with Docker 1.29 and 1.3
Reiterating the mentions to trigger a notification: <detailsIn response to : - Thanks for the info! - Well we can confirm that kubernetes is not working properly with Docker 1.29 and 1.3 Instructions for interacting with me using PR comments are available . If you have questions or suggestions related to my behavior, please file an issue against the repository. </details
This is not really a bug since kubernetes doesn't support the docker version you use yet, but feel free to send a patch if you find the problem.
I was thinking about your comment and I think it is still a bug since downgrading Kubernetes to 1.6 fixes the problem while having the same setup as described above. So something have changed in 1.7. But yeah. Will try to investigate on my own.
I'm actually getting this same error with 1.7.1 and docker 1.13.1. Anyone have other thoughts on what the issue might be here? I found this so question () but it looks like everything is configured correctly.
In kubernetes 1.7, under pid # 1, there is a "/ pause" process, and since init takes pid 1, it is no longer available. In earlier versions of kubernetes, pid # 1 was free . PID USER TIME COMMAND 1 root 0:00 /pause 7 root 3:41 /tiller Kubernetes now shares a single PID namespace among all containers in a pod when running with docker = 1.13.1. This means processes can now signal processes in other containers in a pod, but it also means that the pattern will cause the pod to be restarted rather than a single container.
I can work around the problem using the option in the kubelet, however this not the desired solution of course.
just FYI, looks like some images have to be run as PID 1.
In 1.7 release, we enabled shared pid namespace if the docker version is docker 1.13 and beyond for debug pod feature. Do anyone know why those images, such as GlusterFS have to run as PID 1? we need to figure out how to resolve this conflict with shared pid namespace. If we cannot, we have to disable that setting for 1.8 since we scheduled to support docker 1.13 in 1.8 timeframe. I am currently assigning you this bug to come up a solution.
cc/
gluster/gluster-centos is a container image that runs systemd so that it can run ntpd, crond, gssproxy, glusterd & sshd inside a single container. This isn't how Kubernetes is intended to be used and I don't know how much we should go out of our way to support it (this is a question for & seems to be a good write up of the challenges of running systemd inside of docker. It also prevents Kubernetes from doing process management like: reporting state of processes signaling individual processes for graceful restart ingesting and display daemon output (to stdout/err) Ideally we could change this many-processes-in-a-container to be many-containers-in-a-pod, something like this: This doesn't need a privileged container and doesn't run sshd or ntpd, neither of which are needed in Kubernetes. This also doesn't run crond, but that may actually be needed by gluster. I've never used gluster. (I used flags so I didn't have to investigate how to make these processes log to stdout) If you must run systemd in a container, adding this to the container config will get systemd to run: This tells systemd to run in system mode even though it's not PID 1 and disables its chroot detection (which is unrelated to PID 1 but checked when invoked as "systemd", I guess).
afaict, running in a container is well recommended ( and ) at certain scenarios and a common practice. iic, there are enough containers who make use of as its . If shared namespace which introduced in 1.7 breaks this, I believe its a backward compatibility break :(. I would invite here to share his thoughts as well. :)
Those articles are about how to work around shortcomings in vanilla docker that Kubernetes solves natively: resource sharing via pods, containing via SELinux, reaping orphaned zombies, etc. My earlier question was along the lines of how much effort should go into supporting use cases that are not using Kubernetes as intended. (I'm actually asking, not trying to make a point.) Does Kubernetes commit to continuing support for every container image that's ever run on Kubernetes? For how long? Indefinitely? or can we change it over the course of multiple releases? Anyway, this change is compatible with running an init system in a container. The problem is with images that assume they will only ever have , which has so far been the case with docker due to a technical limitation, but it was never the case with other runtimes such as rkt, hyperv, etc. Brainstorming other options: shared pid namespace and require users of systemd to set an environment variable in their Kubernetes config (or port the multi-process container to a multi-container pod). shared pid namespace and enable it in a future release where we have the same problem. a solution where pid namespace is configurable per-pod, but not supported indefinitely. It would probably be implemented using annotations, and we will have to modify the Container Runtime Interface to support it. Over the course of multiple releases the default behavior would change but could be reverted based on the presence of an annotation. In a future release, users will have to change an annotation in their config to get the old behavior (rather than the environment variable). In a future future release, the annotation will stop working and users will have to set the environment variable. to supporting per-pod shared vs isolated pid namespaces indefinitely and adding it to the Kubernetes API. It doesn't make sense in some runtimes, so we probably can't require all runtimes to implement it, so it'll likely only see use with Docker. Last time we discussed it in SIG Node, and didn't want to support isolated pid namespaces indefinitely.
Yes running systemd in a container is a critical need for us. There are lots of situations where it is and will be used. Biggest use case if for people simply moving current workloads that run in a VM into a container. I have a service that runs fun under systemd in a VM. If I can simply take the init script and move it whole sale into a container, why wouldn't I want to do this. It's simple and does require a great deal of knowledge by the end user. service containers. Not every project can easily be moved into microservices. But they probably can run inside of containers. If we drop support for systemd running inside of containers, then we loose a big group of users. Getting access to journald information inside of the container. Applications that write to syslog and directly to the journal. Currently in container world without systemd, this information is dropped on the floor. if I run systemd and journald, I can actually retrieve and use this information.
If the intension is to force all containers inside of a POD to run with the same PID Namespace? I think this is a mistake since it eliminates another really cool use case. I would love to be able to run two containers inside of a pod, and INIT container with escallated privileges and a locked down container, with no privileges. I want to make sure the locked down container can not see the processes of the privileged container. An example of this, might be a container that loads a kernel module that is needed by the locked down container. Another use case would be a buildah container. The INIT container mounts up a COW file system onto a directory on a location that the locked down container can write, The locked down container writes out the data for his image, when the container completes, the INIT container commits the data to the repo. I believe allowing different containers inside of a POD to run with different security and isolated PIDs should not be removed.
none of the things you've mentioned are removed by this change, save using docker to hide other processes in the pod, and I'm not sure why that's a requirement. Is anyone currently using the "privileged sidecar" pattern you describe or is it hypothetical? It just occurred to me that an interesting compromise here might be to only enable shared pid for multi-container pods. This would enable pod semantics for PID when it would make a difference while drop-in docker monoliths keep the PID 1 behavior they're expecting in docker. I'd have to double check, but I'm pretty sure that behavior could be implemented entirely in the dockershim with no API or CRI changes.
Hypothetical, but I am pushing it for a solution for problems I hear from users fairly frequently, where then need big privileges at start and stop of the pod, but not for the time is is available to the network.
ok, thanks. ftr, I think we should continue to support this pattern as well, and I don't think a shared PID namespace prohibits it. I will bring up this issue at Tuesday's sig node meetup if you'd like to join us. Does the config I mentioned in fix the issue with systemd?
Copying from a comment made elsewhere:
Update from SIG Node Meetup: Everyone wants to support these use cases, but we're not yet sure the requirements we want to support medium to long term. is going to sync up with and then we'll figure out what we want to support in a future release. For 1.8 the current plan is to leave docker shared pid namespace enabled by default. Cluster administrators can disable it per-node with the --docker-disable-shared-pid flag. I'll see about whether we should add something back to the release notes.
This seems somewhat backwards. Wouldn't it make more sense to go back to supporting systemd use cases by default NOW (by making the shared PID namespace behavior optional or something) until a final decision is reached and can be advertised to current users?
absolutely ! thank you very much
I think that is the best solution is to make the PID Namespace sharing optional.
- optional at what scope - cluster, node, pod. let's sync up before next sig-node and we can revisit if need be before 1.8 goes out. The main question right now is if pid namespace sharing is opt-in or opt-out. We need to weigh pro/cons of both.
I would expect it at the POD, since pods would have different requirements, not sure why you would want to have this at the cluster or node level.
yes it works :)
awesome, thanks! I'd like to better understand the requirements of people objecting to this change ( I think there's a bit of confusion about what has changed, so let's start with some facts: This container image runs on Kubernetes without changes to the image, but it requires (non-obvious) pod configuration. is nothing inherently incompatible between a shared pid namespace and a process manager like systemd. systemd and other init systems work with pid != 1, but may require special invocation. in this issue is specific to Kubernetes. That is, this container image wouldn't work with vanilla docker PID namespace sharing, either. change does not affect securityContext I can think of a few things that are objectionable about the change, but let's state them as requirements. For example, are these requirements for anyone? Kubernetes must run all containers published on docker hub with no additional pod configuration Kubernetes must run all systemd containers, regardless of how they are built, with zero additional pod configuration. Kubernetes must run this specific container image with zero additional configuration Kubernetes must officially support isolated PID namespaces between containers in a single pod across all runtimes (docker, rkt, hyperv, etc). Configuration changes are ok, but the flag to systemd cannot be used because the documentation says its not useful. I want to use systemd as intended. Rather than having Kubernetes work around this container image, should we patch the Dockerfile to make it compatible with even the native docker shared-pid, unrelated to Kubernetes?
Configuration changes are ok, but the --system flag to systemd cannot be used because the documentation says its not useful. I want to use systemd as intended. We can ask the systemd guys why they recommend never using the --system flag, but I would guess one of the reasons is that processes showing up that were not created in the ancestry of systemd, could cause confusion. I would also guess that running more then one container with systemd --system would not be supported. Kubernetes must officially support isolated PID namespaces between containers in a single pod. This is required so that you can run different containers with different security constraints in the same pod at the same time. Your last comment makes the seem like it is the default, when actually it is the exception. almost no containers run with shared-pid normally. I guess in a side car container, it makes sense to support this scenario, but forcing this as the ONLY way to run containers is limiting.
This is the part I don't understand. Why? What does PID visibility have to do with security constraints? What am I missing? nor do they run with a shared network namespace, but we impose that on docker containers because that's the pod model.
An update from the last SIG Node: we'll disable this by default in 1.8 and revisit for 1.9 I'll use to track that.
if I have a privileged container process in the same pid namespace as a pid in a non priv container, then the container process in the non priv can attack the priv process. Having them in separate pid namespaces gives you better security. Bottom line, you have a potential change where containers that expect to be run as PID 1, whether legitimately or not, could break when you make this change. Kubernetes in my opinion should make it easy to opt out of this behavior.
/priority critical-urgent
[MILESTONENOTIFIER] Milestone Labels Complete Issue label settings: sig/node: Issue will be escalated to these SIGs if needed. priority/critical-urgent: Never automatically move out of a release milestone; continually escalate to contributor and SIG through all available channels. kind/bug: Fixes a bug discovered during the current release. <detailsAdditional instructions available <a href=""here</a</details
Update: is pending review and should be to the v1.8 Milestone to resolve this issue.

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text: It("processes in different containers of the same pod should be able to see each other", func() { // TODO(yguo0905): Change this test to run unless the runtime is // Docker and its version is <1.13. <del> By("Check whether shared PID namespace is enabled.") isEnabled, err := isSharedPIDNamespaceEnabled() </del> <ins> By("Check whether shared PID namespace is supported.") isEnabled, err := isSharedPIDNamespaceSupported() </ins> framework.ExpectNoError(err) if !isEnabled { <del> framework.Skipf("Skipped because shared PID namespace is not enabled.") </del> <ins> framework.Skipf("Skipped because shared PID namespace is not supported by this docker version.") </ins> } By("Create a pod with two containers.")