containers-workshop/3.running_container.md at main · lcostea/containers-workshop · GitHub

Running containers = containerized processes

Namespaces

1.1 Network namespace

In the first terminal:
```
 docker run -d --name=nginx nginx
```
In the second terminal:
```
 docker run --network container:nginx -it alpine:3.19 /bin/sh
```
in the container:
```
     apk add curl

     curl localhost
```
and we don't have any nginx running
```
     ps aux
```
In the third terminal, we can run another container in a new network namespace (and we want it to be a privileged container):
```
 docker run --privileged -it alpine:3.19 /bin/sh
```
In the first terminal:
```
 docker logs nginx

 docker stop nginx
```
After stop, if we try again curl it will not work anymore

1.2 Time namespace

In all the terminals get the current date and time:
```
 date
```
Set a new time in the third terminal:
```
 date +%T -s "18:50:13"
```
And again in all the terminals get the current date and time:
```
 date
```
cgroups and chroot
- no demos
Docker daemon to containerd to runc

docker run -it alpine:3.19 /bin/sh and run sleep 180 in the container

docker run -it --pid=host ubuntu:20.10 /bin/sh and then inside the container run:
```
 apt-get update

 apt-get install -y psmisc

 ps -fC sleep #it will allow to the the sleep PID

 pstree -sg sleep_PID

 ps aux | grep docker
```