Impossible service via kubectl expose

czezz · October 22, 2020, 3:26pm

Hi all,
I am following this tutorial:

And I puzzled what command “kubectl expose” actually does:
kubectl expose deployment hello-node --type=LoadBalancer --port=8080

I assume it exposes/shares service running on port 8080 inside pod/container hello-node.
This service is to be exposed publically via port 30397.

user1@user:~$ kubectl get service
NAME         TYPE           CLUSTER-IP    EXTERNAL-IP   PORT(S)          AGE
hello-node   LoadBalancer   10.99.96.18   <pending>     8080:30397/TCP   84m
kubernetes   ClusterIP      10.96.0.1     <none>        443/TCP          4d2h

However, I do NOT see any service LISTENING on port 8080 inside of hello-node container
docker exec -it 74d84fd550c8 ss -ln | grep 8080

Question: why this tutorial asks me to expose service on port 8080 when there is no such service on the pod/container?

stephendotcarter · October 22, 2020, 8:34pm

The ss command is not available in that container.

root@924faddaa888:~# ss
bash: ss: command not found

Here is the output if I exec in and curl port 8080:

root@924faddaa888:/# curl 127.0.0.1:8080
CLIENT VALUES:
client_address=127.0.0.1
command=GET
real path=/
query=nil
request_version=1.1
request_uri=http://127.0.0.1:8080/

SERVER VALUES:
server_version=nginx: 1.10.0 - lua: 10001

HEADERS RECEIVED:
accept=*/*
host=127.0.0.1:8080
user-agent=curl/7.47.0
BODY:
-no body in request-

Also the nginx config inside the container shows port 8080:

root@924faddaa888:/etc/nginx# cat /etc/nginx/nginx.conf | grep 8080  
        listen 8080 default_server reuseport;

Kind regards,
Stephen

czezz · October 23, 2020, 8:22am

Hi Stephen,
Thank you very much for your reply but you are wrong OR i am keep doing something wrong:

user1@user:~$ docker ps
CONTAINER ID        IMAGE                                 COMMAND                  CREATED             STATUS              PORTS                                                                                                      NAMES
74d84fd550c8        gcr.io/k8s-minikube/kicbase:v0.0.13   "/usr/local/bin/entr…"   4 days ago          Up 45 hours         127.0.0.1:32771->22/tcp, 127.0.0.1:32770->2376/tcp, 127.0.0.1:32769->5000/tcp, 127.0.0.1:32768->8443/tcp   minikube

user1@user:~$ docker exec -it 74d84fd550c8 /bin/bash
root@minikube:/# which ss
/usr/bin/ss

root@minikube:/# curl 127.0.0.1:8080
curl: (7) Failed to connect to 127.0.0.1 port 8080: Connection refused

root@minikube:/# curl 127.0.0.1:8080
curl: (7) Failed to connect to 127.0.0.1 port 8080: Connection refused

root@minikube:/# cat /etc/nginx/nginx.conf | grep 8080
cat: /etc/nginx/nginx.conf: No such file or directory

stephendotcarter · October 23, 2020, 8:48am

Hi @czezz,

You are docker execing in to the Minikube container, not the echoserver pod.

Instead, try running kubectl get pods
And then kubectl exec in to the echoserver pod.

Kind regards,
Stephen

czezz · October 23, 2020, 3:02pm

Hi Stephen,
Thank you very much fro reply.
Yes, indeed you are right, it works this way but it brings a lot of questions…

Questions:

I assume hello-node POD/Deployment contains inside docker container: 74d84fd550c8 - correct?
If so, where is actually nginx installed?
On Docker I see processes but no files and SOCKET on port 8080:

user1@user:~$ docker exec -it 74d84fd550c8 /bin/bash
root@minikube:/# ps -ef | grep nginx
root 148699 148683 0 00:19 ? 00:00:00 nginx: master process nginx -g daemon off;
nobody 148713 148699 0 00:19 ? 00:00:00 nginx: worker process

whereas, inside POD/Deployment I see nginx files, SOCKET on port 8080 and cant really display “ps”:

user1@user:~$ kubectl exec hello-node-7567d9fdc9-qjgvk – find / -type f -iname “nginx”
/usr/sbin/nginx
/run/nginx.pid
/etc/nginx/nginx.conf.default
/etc/nginx/nginx.conf

Does that mean nginx is partly installed on hello-node POD/Deployment and partly on Docker?

tej-singh-rana · October 23, 2020, 3:13pm

Hey, @czezz

Pod is not running your application container, it’s just giving the environment to that apps container. Environment could be anything, In respect of namespace, network, volume etc.
Behind the scene it uses Docker to run your application inside the container.

Did you check the nginx.conf file ?
Must be port 8080 preconfigured.

czezz · October 23, 2020, 3:19pm

Hi @tej-singh-rana,
Yes, it is as @stephendotcarter has already mentioned and I confirmed that. I am not asking for that.

tej-singh-rana · October 23, 2020, 3:21pm

Hope this article helps.

czezz · October 23, 2020, 3:26pm

Thanks @tej-singh-rana, already read it before.

I post here my questions again:
Questions:

where is actually nginx installed?
On Docker I see processes but no files and SOCKET on port 8080:

user1@user:~$ docker exec -it 74d84fd550c8 /bin/bash
root@minikube:/# ps -ef | grep nginx
root 148699 148683 0 00:19 ? 00:00:00 nginx: master process nginx -g daemon off;
nobody 148713 148699 0 00:19 ? 00:00:00 nginx: worker process

whereas, inside POD/Deployment I see nginx files, SOCKET on port 8080 and cant really display “ps”:

user1@user:~$ kubectl exec hello-node-7567d9fdc9-qjgvk – find / -type f -iname “nginx”
/usr/sbin/nginx
/run/nginx.pid
/etc/nginx/nginx.conf.default
/etc/nginx/nginx.conf

Does that mean nginx is partly installed on hello-node POD/Deployment and partly on Docker?

czezz · October 23, 2020, 6:48pm

The more I read the the less I understand.
Everywhere I read they says: Kubernetes is a wrapper for container/s.

Question:
If so, why in this case nginx is NOT installed inside of docker container (74d84fd550c8) but on a pod (hello-node)?

user1@user:~$ docker ps
CONTAINER ID        IMAGE                                 COMMAND                  CREATED             STATUS              PORTS                                                                                                      NAMES
74d84fd550c8        gcr.io/k8s-minikube/kicbase:v0.0.13   "/usr/local/bin/entr…"   5 days ago          Up 2 days           127.0.0.1:32771->22/tcp, 127.0.0.1:32770->2376/tcp, 127.0.0.1:32769->5000/tcp, 127.0.0.1:32768->8443/tcp   minikube
user1@user:~$ docker exec 74d84fd550c8 cat /etc/hostname
minikube
user1@user:~$ docker exec 74d84fd550c8 which nginx
{this means there is no nginx binary/package}

user1@user:~$ kubectl get po
NAME                          READY   STATUS    RESTARTS   AGE
hello-node-7567d9fdc9-qjgvk   1/1     Running   0          35h
user1@user:~$ kubectl exec hello-node-7567d9fdc9-qjgvk -- cat /etc/hostname
hello-node-7567d9fdc9-qjgvk

user1@user:~$ kubectl exec hello-node-7567d9fdc9-qjgvk -- which nginx
/usr/sbin/nginx <--- {this means nginx is here}

stephendotcarter · October 24, 2020, 7:44pm

The container running nginx is running inside the minikube docker container.
You can’t see the port using normal means because it’s running in a different namespace.

Try this, docker exec in to the minikube container.

Then:

lsns | grep nginx

The using the 4th number which is the PID:

nsenter -t 6831 --net ss -lpn | grep 8080

You have to keep in mind that because you are running minikube, your entire Kubernetes cluster is running inside a container which make everything slightly more complicated to get your head around.
From inside the minikube container, you can also run docker ps to see the containers running inside the minikube container:

docker ps

Kind regards,
Stephen

czezz · October 26, 2020, 7:30pm

Hi Stephen,
Thank you very much for reply.

By digging deeper of what you showed with nsenter, I tried this:

user1@user:~$ docker exec -it 74d84fd550c8 /bin/bash
root@minikube:~# nsenter -t 2437 -m
-bash: mesg: command not found
*{now I am in the namespace}*
# ls -al /etc/nginx/nginx.conf
-rw-r----- 1 root root 2119 May 28  2016 /etc/nginx/nginx.conf

It looks like this is what I see inside of the POD:

user1@user:~$ kubectl exec hello-node-7567d9fdc9-qjgvk – find / -type f -iname “nginx”
/usr/sbin/nginx
/run/nginx.pid
/etc/nginx/nginx.conf.default
/etc/nginx/nginx.conf  <--- HERE

Question:
Does that mean that in fact POD hello-node-7567d9fdc9-qjgvk is what NGINX namespace is on the docker?
See picture to better understand what I mean?

–
For the docker ps inside docker container (74d84fd550c8), i will get back later. This is too much at once but I see there 23 k8s images.

stephendotcarter · October 26, 2020, 8:06pm

Yes thats accurate, but again, keep in mind that you are trying to understand minikube, which is a kind of “nested” Kubernetes in a container.

Usually with Kubernetes the processes running inside docker container 74d84fd550c8 would be spread across multiple control plane and worker VM. Kubernetes just runs your pod as one or more Docker containers on a worker VM.

My suggestion is don’t get too obsessed with the low level details as some are minikube specific. Understanding the higher level constructs of Kubernetes is far more beneficial.
But if you want to learn more low level, keep asking questions because this is helping me learn too

Kind regards,
Stephen

czezz · October 27, 2020, 4:31pm

Hi Stephen,
I learn a lot with you too

In other words Kubernetes creates Namespace for nginx processes inside of Docker container.
Whereas Docker container itself is an namespace of global/default namespace - host.
In other words - Kubernetes exposes docker’s namespaces as PODs.

If so, sentence under following link: Pods | Kubernetes
“you can think of a Pod as a wrapper around a single container” is highly misleading - in my opinion.

I would put it that way: “you can think of Pod as a wrapper around container’s dedicated namespace”

Here is full picture of my understanding (so far)

And here is a few more exercises I did today to better understand what is happening under the hood:

root@user:/home/user1# docker ps
CONTAINER ID        IMAGE                                 COMMAND                  CREATED             STATUS              PORTS                                                                                                      NAMES
74d84fd550c8        gcr.io/k8s-minikube/kicbase:v0.0.13   "/usr/local/bin/entr…"   9 days ago          Up 21 hours         127.0.0.1:32771->22/tcp, 127.0.0.1:32770->2376/tcp, 127.0.0.1:32769->5000/tcp, 127.0.0.1:32768->8443/tcp   minikube
user1@user:~$ docker inspect 74d84fd550c8 | grep -i pid
            "Pid": 2717,
            "PidMode": "",
            "PidsLimit": null,

user1@user:~$ sudo lsns -p 2717
        NS TYPE   NPROCS   PID USER COMMAND
4026531835 cgroup    268     1 root /sbin/init maybe-ubiquity
4026531837 user      267     1 root /sbin/init maybe-ubiquity
4026532268 mnt        32  2717 root /sbin/init
4026532269 uts        38  2717 root /sbin/init
4026532270 ipc        32  2717 root /sbin/init
4026532271 pid        32  2717 root /sbin/init
4026532273 net        44  2717 root /sbin/init

user1@user:~$ sudo nsenter -m -u -p -n -i -t 2717 bash
root@minikube:/# <-- im in docker container: 74d84fd550c8 == docker exec -it 74d84fd550c8 /bin/bash



root@minikube:/# lsns -p 2437
        NS TYPE   NPROCS   PID USER COMMAND
4026531835 cgroup     58     1 root /sbin/init
4026531837 user       58     1 root /sbin/init
4026532423 ipc         4  2166 root /pause
4026532426 net         4  2166 root /pause
4026532499 mnt         3  2437 root nginx: master process nginx -g daemon off;
4026532500 uts         3  2437 root nginx: master process nginx -g daemon off;
4026532501 pid         3  2437 root nginx: master process nginx -g daemon off;


root@minikube:/# sudo nsenter -m -u -p -n -i -t 2437 bash
root@hello-node-7567d9fdc9-qjgvk:/# <-- im in nginx namespace stands for hello-node-7567d9fdc9-qjgvk pod == kubectl exec -ti hello-node-7567d9fdc9-qjgvk -- /bin/bash




user1@user:~$ ps auxf -ww
...
root         739  0.0  1.2 969252 26384 ?        Ssl  05:25   0:17 /usr/bin/containerd
root        2693  0.0  0.1 110128  3428 ?        Sl   05:33   0:00  \_ containerd-shim -namespace moby -workdir /var/lib/containerd/io.containerd.runtime.v1.linux/moby/74d84fd550c8b008bcd0ce3d92f764942a310bdcb9b3a25199e7241e92a6078d -address /run/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        2717  0.0  0.2 169284  4088 ?        Ss   05:33   0:00      \_ /sbin/init
root        2924  0.0  0.2  29240  4232 ?        S<s  05:33   0:00          \_ /lib/systemd/systemd-journald
root        2935  0.0  0.0   5568   760 ?        Ss   05:33   0:00          \_ /usr/sbin/cron -f
_apt        2938  0.0  0.0 224092   504 ?        Ssl  05:33   0:00          \_ /usr/sbin/rsyslogd -n -iNONE
root        2944  0.0  1.0 896420 20412 ?        Ssl  05:33   0:16          \_ /usr/bin/containerd
root        2955  1.2  2.8 1344932 57716 ?       Ssl  05:33   7:34          \_ /usr/bin/dockerd -H tcp://0.0.0.0:2376 -H unix:///var/run/docker.sock --default-ulimit=nofile=1048576:1048576 --tlsverify --tlscacert /etc/docker/ca.pem --tlscert /etc/docker/server.pem --tlskey /etc/docker/server-key.pem --label provider=docker --insecure-registry 10.96.0.0/12
root        2987  0.1  1.1 1404412 23508 ?       Ssl  05:33   0:46          |   \_ containerd --config /var/run/docker/containerd/containerd.toml --log-level info
root        4346  0.0  0.0 108700   540 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/d1f5928a50227ff021bba2e50621139f90563e853e1d01db383b1e672df45048 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4419  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        4347  0.0  0.0 110108   772 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/723398c6fe35cc22357db12f7ca8c7add7b06a22c4f3a200430d10d4697f6b12 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4405  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        4348  0.0  0.0 110108   508 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/9d45aee0944c4d35b263ee81f6f06fd234cced5be7e238c239928162db8e223e -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4426  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        4465  0.0  0.0 108700   616 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/60bf4ef2010fb5a59a9cd398f9904554c5a35276f7c84e202035518332b0b619 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4520  3.6 13.0 1096456 265740 ?      Ssl  05:33  21:53          |       |   \_ kube-apiserver --advertise-address=192.168.49.2 --allow-privileged=true --authorization-mode=Node,RBAC --client-ca-file=/var/lib/minikube/certs/ca.crt --enable-admission-plugins=NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,NodeRestriction,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,ResourceQuota --enable-bootstrap-token-auth=true --etcd-cafile=/var/lib/minikube/certs/etcd/ca.crt --etcd-certfile=/var/lib/minikube/certs/apiserver-etcd-client.crt --etcd-keyfile=/var/lib/minikube/certs/apiserver-etcd-client.key --etcd-servers=https://127.0.0.1:2379 --insecure-port=0 --kubelet-client-certificate=/var/lib/minikube/certs/apiserver-kubelet-client.crt --kubelet-client-key=/var/lib/minikube/certs/apiserver-kubelet-client.key --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname --proxy-client-cert-file=/var/lib/minikube/certs/front-proxy-client.crt --proxy-client-key-file=/var/lib/minikube/certs/front-proxy-client.key --requestheader-allowed-names=front-proxy-client --requestheader-client-ca-file=/var/lib/minikube/certs/front-proxy-ca.crt --requestheader-extra-headers-prefix=X-Remote-Extra- --requestheader-group-headers=X-Remote-Group --requestheader-username-headers=X-Remote-User --secure-port=8443 --service-account-key-file=/var/lib/minikube/certs/sa.pub --service-cluster-ip-range=10.96.0.0/12 --tls-cert-file=/var/lib/minikube/certs/apiserver.crt --tls-private-key-file=/var/lib/minikube/certs/apiserver.key
root        4482  0.0  0.0 110108   564 ?        Sl   05:33   0:01          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/f9ff3d2aa5af12ccec1178847c4001070fef8819c0184890ea23dd275d52afa4 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4534  0.9  2.9 10612724 59068 ?      Ssl  05:33   5:41          |       |   \_ etcd --advertise-client-urls=https://192.168.49.2:2379 --cert-file=/var/lib/minikube/certs/etcd/server.crt --client-cert-auth=true --data-dir=/var/lib/minikube/etcd --initial-advertise-peer-urls=https://192.168.49.2:2380 --initial-cluster=minikube=https://192.168.49.2:2380 --key-file=/var/lib/minikube/certs/etcd/server.key --listen-client-urls=https://127.0.0.1:2379,https://192.168.49.2:2379 --listen-metrics-urls=http://127.0.0.1:2381 --listen-peer-urls=https://192.168.49.2:2380 --name=minikube --peer-cert-file=/var/lib/minikube/certs/etcd/peer.crt --peer-client-cert-auth=true --peer-key-file=/var/lib/minikube/certs/etcd/peer.key --peer-trusted-ca-file=/var/lib/minikube/certs/etcd/ca.crt --proxy-refresh-interval=70000 --snapshot-count=10000 --trusted-ca-file=/var/lib/minikube/certs/etcd/ca.crt
root        4483  0.0  0.0 108700   756 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/41eeda21f67cabdeacc9ae4ad34a429144e75c687b90f3cc4b50d7409e4db200 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4526  1.1  2.3 811368 47736 ?        Ssl  05:33   6:49          |       |   \_ kube-controller-manager --authentication-kubeconfig=/etc/kubernetes/controller-manager.conf --authorization-kubeconfig=/etc/kubernetes/controller-manager.conf --bind-address=127.0.0.1 --client-ca-file=/var/lib/minikube/certs/ca.crt --cluster-name=mk --cluster-signing-cert-file=/var/lib/minikube/certs/ca.crt --cluster-signing-key-file=/var/lib/minikube/certs/ca.key --controllers=*,bootstrapsigner,tokencleaner --kubeconfig=/etc/kubernetes/controller-manager.conf --leader-elect=false --port=0 --requestheader-client-ca-file=/var/lib/minikube/certs/front-proxy-ca.crt --root-ca-file=/var/lib/minikube/certs/ca.crt --service-account-private-key-file=/var/lib/minikube/certs/sa.key --use-service-account-credentials=true
root        4680  0.0  0.0 108700   596 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/46ac8114ff14d7b78c2ae07a6e58182866b8d0ca8119d1504b604e7c38a96ed7 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4724  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        4735  0.0  0.0 108700   740 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/36af84a1bf148b24620952d0af1c9e5431dabe0f52d0133d76aa532244d1b9ea -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        4751  0.1  0.8 746652 17972 ?        Ssl  05:33   1:00          |       |   \_ kube-scheduler --authentication-kubeconfig=/etc/kubernetes/scheduler.conf --authorization-kubeconfig=/etc/kubernetes/scheduler.conf --bind-address=127.0.0.1 --kubeconfig=/etc/kubernetes/scheduler.conf --leader-elect=false --port=0
root        5011  0.0  0.0 108700   776 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/0c4911a2b46f87ee4c216e35c6d12c1025f9963420fb36166a1e52452251c6f9 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5033  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5056  0.0  0.0 108700   596 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/d4022f2bb2884b4716dd50102149315bcc7c41fc2be7a1d8e3fbea94d6d8be24 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5104  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5062  0.0  0.0 108700   728 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/d12665ab45df1b305c7957e5d2a0ec876c4c5b7d51636fb9af9a9697824d3c7b -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5099  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5130  0.0  0.0 110108   600 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/506698be21ec585bfe6c7572eba227d620f61bdc996c08cc0eebf5b898336949 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5192  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5220  0.0  0.0 110108   816 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/a1187ccfa9bd45212314367cbc82c9884ebaf3dffdf998efe027a49826d23670 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
nobody      5242  0.0  0.3 743156  6528 ?        SLsl 05:33   0:05          |       |   \_ /tiller
root        5249  0.0  0.0 110108   616 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/fad5e4cdadf58994a78fa98ccfe50d8b7ff15020ac9e45779d67ff0166068687 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5300  0.0  0.7 743408 14948 ?        Ssl  05:33   0:04          |       |   \_ /usr/local/bin/kube-proxy --config=/var/lib/kube-proxy/config.conf --hostname-override=minikube
root        5380  0.0  0.0 108700   616 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/7fe3b7d628dba65931e24b6c6704d3a1af69616341937765b6b60ba107ef46b0 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5449  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5405  0.0  0.0 108700   924 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/e5a5abd22c3c43e31ef338a0107b5a04d7af02ccc998eb5510ded11d6161d2cb -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5430  0.0  0.0  42888  1000 ?        Ss   05:33   0:00          |       |   \_ nginx: master process nginx -g daemon off;
nobody      5503  0.0  0.0  43340  1140 ?        S    05:33   0:00          |       |   |   \_ nginx: worker process
root       15448  0.0  0.0  18228   568 pts/0    Ss+  06:15   0:00          |       |   \_ /bin/bash
root        5455  0.0  0.0 108700   840 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/8e7ebb37dd616576a1abe373e2abdd3b8440fed45f43ab9ec6657c5d56ded215 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5495  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5466  0.0  0.0 108700   708 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/26a26134e8017ab0b11afbe4c63ee56abcd39f9da2a520c9ad84b90298e8dabc -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5512  0.0  0.0    964     4 ?        Ss   05:33   0:00          |       |   \_ /pause
root        5689  0.0  0.0 108700   760 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/0f8198266867b08aa564f1df7c4944d69aa353d8c9b3df774d7313e3233c19ae -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root        5750  0.2  0.6 747400 14084 ?        SLsl 05:33   1:16          |       |   \_ /coredns -conf /etc/coredns/Corefile
root        5690  0.0  0.0 108700   608 ?        Sl   05:33   0:01          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/35dbf007478374a58a84f3fb3c72b0b5204b7139f93db595cea857abb5cc6d36 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
user        5763  0.0  0.1 400484  3412 ?        Ssl  05:33   0:03          |       |   \_ /metrics-sidecar
root        5694  0.0  0.0 110108   580 ?        Sl   05:33   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/1b9adff49d51f82b32795182b80136ec3263e0ecb9f92cd3f20f58590c9521c5 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
user        5752  0.0  0.7 738016 15608 ?        SLsl 05:33   0:11          |       |   \_ /dashboard --insecure-bind-address=0.0.0.0 --bind-address=0.0.0.0 --namespace=kubernetes-dashboard --enable-skip-login --disable-settings-authorizer
root       28475  0.0  0.0 110108   644 ?        Sl   07:18   0:00          |       \_ containerd-shim -namespace moby -workdir /var/lib/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby/00a54ebff34a65609c63f7b02d6deb64de8e8333cd42142709e7c1712700d6e1 -address /var/run/docker/containerd/containerd.sock -containerd-binary /usr/bin/containerd -runtime-root /var/run/docker/runtime-runc
root       28503  0.1  0.7 733960 14492 ?        Ssl  07:18   0:33          |           \_ /storage-provisioner
root        2956  0.0  0.0  12160  1132 ?        Ss   05:33   0:00          \_ sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups
root        3012  0.0  0.0  12020   500 ?        Ss   05:33   0:00          \_ /usr/sbin/xinetd -pidfile /run/xinetd.pid -stayalive -inetd_compat -inetd_ipv6
root        3626  3.3  3.0 1932300 62468 ?       Ssl  05:33  20:22          \_ /var/lib/minikube/binaries/v1.19.2/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --config=/var/lib/kubelet/config.yaml --container-runtime=docker --hostname-override=minikube --kubeconfig=/etc/kubernetes/kubelet.conf --node-ip=192.168.49.2

stephendotcarter · October 28, 2020, 8:36am

I don’t think its misleading.

What is a container? There is no such thing in Linux. Its just a process running in restricted namespaces (pid, mnt, net, etc…) so it appears isolated. And we call that abstraction a container.

What is a pod? Again I don’t think there is such a thing at the OS level, its just some containers sharing some namespaces. It is the Kubernetes abstraction of one or more containers running together which share some namespaces.

Kind regards,
Stephen

czezz · October 30, 2020, 3:29pm

I just learnt that my statement about NS inside of Docker is not necessarily true.
I have just bumped into a POD where service is just running inside of Docker (and not NS inside Docker).
Apparently it depends from who mood of the one who builds/prepare specific POD.

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Impossible service via kubectl expose

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