What are the pause containers?

docker hibernate container
kubernetes pid 1
container network interface kubernetes
why we need pod in kubernetes
why does kubernetes use pods
docker resume container
kubernetes networking internals
ecs pause container

In my IBM Cloud Private, I see several pause containers.

Can anyone explain the purpose of these? Normally, I can get to the bash shell in a running container but not the ones which are pause.

# docker ps | grep pause
ee5f3f6b9fc0        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_catalog-catalog-apiserver-8qxrf_kube-system_3b4b107d-0b72-11e8-9f22-005056227136_0
d238dad0c5b8        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_auth-apikeys-bk28g_kube-system_3b731880-0b72-11e8-9f22-005056227136_0
0196efb043ca        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_icp-router-htnhz_kube-system_3b8d25d3-0b72-11e8-9f22-005056227136_0
b09dc1759d09        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_unified-router-bskb6_kube-system_3af9d44e-0b72-11e8-9f22-005056227136_0
8a392f174c24        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_auth-pap-gfh7q_kube-system_3aa5b311-0b72-11e8-9f22-005056227136_0
0ac776eb9ced        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_platform-api-zr5pz_kube-system_3b2ce527-0b72-11e8-9f22-005056227136_0
107896ebfcd6        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_icp-ds-0_kube-system_3a9200f8-0b72-11e8-9f22-005056227136_0
f95df5fbcc4a        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_image-manager-0_kube-system_3ae74f5c-0b72-11e8-9f22-005056227136_0
a9d30804f222        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_auth-idp-h4fmt_kube-system_3ad78a99-0b72-11e8-9f22-005056227136_0
eaae55900637        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_catalog-ui-jv9sq_kube-system_3af5cb32-0b72-11e8-9f22-005056227136_0
4ace18a84d8b        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_auth-pdp-9vhzx_kube-system_3ae0a074-0b72-11e8-9f22-005056227136_0
98b70f6074c7        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_calico-policy-controller-5997c6c956-cx774_kube-system_39bfecef-0b72-11e8-9f22-005056227136_0
63a0340e3de8        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_rescheduler-jqtd4_kube-system_3a6d4b05-0b72-11e8-9f22-005056227136_0
cace008e71b1        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_kube-dns-9494dc977-7gwpx_kube-system_39a15b6b-0b72-11e8-9f22-005056227136_0
80a18b538ef3        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_platform-ui-k5g7h_kube-system_3a98aad3-0b72-11e8-9f22-005056227136_0
bea43bfc8d70        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_catalog-catalog-controller-manager-bd9f49c8c-4fqcp_kube-system_39653745-0b72-11e8-9f22-005056227136_0
f54f329e50ae        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_helm-api-5d8b6d6f9c-4rl2s_kube-system_396ade8d-0b72-11e8-9f22-005056227136_0
6812e3fee9cc        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_tiller-deploy-55fb4d8dcc-pcxbj_kube-system_396b0005-0b72-11e8-9f22-005056227136_0
69a840bc394b        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_helmrepo-5878d9d858-wlcrj_kube-system_396506a5-0b72-11e8-9f22-005056227136_0
03bc9ce0413d        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_heapster-5fd94775d5-28t6w_kube-system_396b0dd6-0b72-11e8-9f22-005056227136_0
8763167695b3        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_filebeat-ds-amd64-q54pc_kube-system_9b8515d6-0b52-11e8-99a8-005056227136_1
461e5de11ee1        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_calico-node-amd64-ql292_kube-system_53492619-0b51-11e8-99a8-005056227136_1
f73e2eb9dbaf        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_k8s-master-192.168.142.103_kube-system_c39080358687c72432da5f6de4b6fff9_1
c08f029af60e        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_k8s-mariadb-192.168.142.103_kube-system_6b640df7dae2cb064ebc450b273ce62a_1
0174b5c35963        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_k8s-proxy-192.168.142.103_kube-system_b9f441de4995384d245d71fdb65e2cc2_1
f6befd10c479        ibmcom/pause:3.0    "/pause"                 About an hour ago   Up About an hour                        k8s_POD_k8s-etcd-192.168.142.103_kube-system_a5150d8f6ee1f8047b05f9b2d5cbcaba_1

The 'pause' container is a container which holds the network namespace for the pod. Kubernetes creates pause containers to acquire the respective pod’s IP address and set up the network namespace for all other containers that join that pod.

You can access below links for details.

https://groups.google.com/forum/#!topic/kubernetes-users/jVjv0QK4b_o

https://www.ianlewis.org/en/almighty-pause-container

The Almighty Pause Container, The docker pause command suspends all processes in the specified containers. On Linux, this uses the freezer cgroup. Traditionally, when suspending a  In Kubernetes, the pause container serves as the "parent container" for all of the containers in your pod. The pause container has two core responsibilities. First, it serves as the basis of Linux namespace sharing in the pod. And second, with PID (process ID) namespace sharing enabled, it serves as PID 1 for each pod and reaps zombie processes.

yes, the pause container is part of each pod that is responsible to create shared network, assign ip address within the pod for all business containers inside this pod, also the pause container shared the volume for entire pod. If the pause container is dead, kubernetes consider the pod died and kill it and reschedule a new one.

docker pause, Related commands . Command, Description. docker container attach, Attach local standard input, output, and error streams to a running container. Question: How to Pause and Resume running containers on docker host?. This post will help to know about pausing and resuming any running containers on the Docker host. Let’s first start the docker container “memory_test” on the docker host.

Pause is a secret container that runs on every pod in Kubernetes. This container’s primary job is to keep the namespace open in case all the other containers on the pod die.

pause, This is done by creating a pause container that “serves as the “parent container” for all of the containers in your pod” [The Almighty Pause  When checking out the nodes of your Kubernetes cluster, you may have noticed some containers called “pause” running when you do a docker ps on the node.

If you docker stop the pause container, you would find that the Pod would have a new internal IP without any change in Restart count of the Pod. However, if you docker stop the container of the Pod, you would find the Pod status as Completed and then if you would docker start the same, you would find Pod in Running again with Restart count of the Pod incremented by 1 with no change in IP.

Kubernetes Networking: Behind the scenes, The pause container is a container which holds the network namespace for the pod. It does nothing 'useful'. (It's actually just a little Pausing containers rely on cgroups freezer which blocks the scheduling of frozen containers. A key difference between pausing and stopping containers is in the persistence of state. When a container is stopped any resources allocated to it such as memory are released while a paused container does not release its allocated resources.

What is the role of 'pause' container?, FAQ Billing. What are Kubernetes pause containers and will they impact my bill? Marc Weisman February 11, 2019 13:32. This content has moved to our new  All the running Docker containers should be stopped. Here, docker container list -q command returns the container ID of all the running Docker containers. Then the docker container stop command stops the containers using the container IDs. As you can see, there is no running Docker containers in the list.

What are Kubernetes pause containers and will they impact my bill , When checking out the nodes of your Kubernetes cluster, you may have noticed some containers called "pause" running when you do a docker ps on the node. What is a Docker Container. A running instance of an image is called a container. Docker launches them using the Docker images as read-only templates. If you start an image, you have a running container of this image. Naturally, you can have many running containers of the same image. We use the command “docker run” to run a container.

The Almighty Pause Container : docker, When checking out the nodes of your Kubernetes cluster, you may have noticed some containers called “pause” running when you do a docker  There are a number of different sizes and shapes of plastic food containers on the market from reusable Rubbermaid or Tupperware containers to the inexpensive, “disposable” products made by Glad and Ziplock. They tend to break down over time, getting pitted, stained or cracked.

Comments
  • Here's a similar question. Note, according to the comments, it appears pause is a relatively new feature. stackoverflow.com/questions/16047960/…
  • Some nice answers about "what is a pause container" can also be found at this question: What work does the process in container gcr.io/google_containers/pause:0.8.0 do?.
  • I dont think "pause" container will assign the ip address but the other containers will see the same ip address as pause container sees ?