Docker rootless - docker

Question

I want to launch a Docker container in a host from a rootless container.
Example:
I have an Ubuntu VM running: gcr.io/news-ml-257304/mycontainer:latest which is rootless.
From this container I want to be able to execute this command:
docker run --network=host -v {connection_file}:/connection-spec gcr.io/news-ml-257304/mycontainer2
and mycontainer2 should start in Ubuntu VM . (Outside mycontainer). Is it possible?
I installed Docker rootless successfully. I can run a rootless container mycontainer successfully.
I'm currently following this guide:
https://docs.docker.com/engine/security/rootless/#prerequisites
docker -v
Docker version 20.10.12, build e91ed57
lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 10 (buster)
Release: 10
Codename: buster
In Host machine:
echo $DOCKER_HOST
unix:///run/user/1000/docker.sock
systemctl --user status docker
● docker.service - Docker Application Container Engine (Rootless)
Loaded: loaded (/home/gogasca/.config/systemd/user/docker.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2022-02-13 01:16:14 UTC; 9min ago
Docs: https://docs.docker.com/go/rootless/
Main PID: 28166 (rootlesskit)
CGroup: /user.slice/user-1000.slice/user#1000.service/docker.service
├─28166 rootlesskit --net=slirp4netns --mtu=65520 --slirp4netns-sandbox=auto --slirp4netns-seccomp=auto --disable-host-loopback --port-driver=builtin --copy-up=/etc --copy-up=/run --propaga
├─28177 /proc/self/exe --net=slirp4netns --mtu=65520 --slirp4netns-sandbox=auto --slirp4netns-seccomp=auto --disable-host-loopback --port-driver=builtin --copy-up=/etc --copy-up=/run --prop
├─28195 slirp4netns --mtu 65520 -r 3 --disable-host-loopback --enable-sandbox --enable-seccomp 28177 tap0
├─28202 dockerd
├─28217 containerd --config /run/user/1000/docker/containerd/containerd.toml --log-level info
├─29019 fuse-overlayfs -o lowerdir=/home/gogasca/.local/share/docker/fuse-overlayfs/l/QJ2Y7NAKB4N3ABA4CVINPOT64L:/home/gogasca/.local/share/docker/fuse-overlayfs/l/ZDXAGGP2VO2K7FWWEZYSJ2FK5
├─29026 /usr/bin/rootlesskit-docker-proxy -proto tcp -host-ip 127.0.0.1 -host-port 8080 -container-ip 172.17.0.2 -container-port 8080
├─29031 docker-proxy -container-ip 172.17.0.2 -container-port 8080 -host-ip 127.0.0.1 -host-port 8080 -proto tcp
├─29047 /usr/bin/containerd-shim-runc-v2 -namespace moby -id 624b2dbfc5f54272ef8fdf8a5a59da9d3be0d1292e2fdd2f2b22bd0ac0aee21b -address /run/user/1000/docker/containerd/containerd.sock
└─29068 /opt/conda/bin/python3.7 /opt/conda/bin/jupyter-lab --ip=0.0.0.0 --port=8080 --no-browser --allow-root --NotebookApp.token= --NotebookApp.password= --ServerApp.allow_origin=*
Feb 13 01:16:14 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:14.516248592Z" level=info msg="Loading containers: start."
Feb 13 01:16:14 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:14.889430212Z" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon opti
Feb 13 01:16:14 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:14.977066622Z" level=info msg="Loading containers: done."
Feb 13 01:16:14 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:14.992309698Z" level=info msg="Docker daemon" commit=459d0df graphdriver(s)=fuse-overlayfs version=20.10.12
Feb 13 01:16:14 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:14.992798123Z" level=info msg="Daemon has completed initialization"
Feb 13 01:16:15 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:16:15.023274713Z" level=info msg="API listen on /run/user/1000/docker.sock"
Feb 13 01:19:20 a-experiment-debian dockerd-rootless.sh[28166]: time="2022-02-13T01:19:20.515794206Z" level=info msg="starting signal loop" namespace=moby path=/run/.ro729122400/user/1000/docker/conta
This is how I start mycontainer
docker run -d -p 127.0.0.1:8080:8080/tcp gcr.io/news-ml-257304/mycontainer:latest -v /home/gogasca/local/:/home/jupyter -e DOCKER_HOST=$DOCKER_HOST
When I access mycontainer and check docker I get:
docker exec -it 624b2dbfc5f5 /bin/bash
docker ps
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
In Host:
echo $DOCKER_HOST
unix:///run/user/1000/docker.sock
In mycontainer DOCKER_HOST shows empty
echo $DOCKER_HOST

Answer 1

This post is five months old, so you've probably already figured this out, but:
Try adding
-v /run/user/1000/docker.sock:/var/run/docker.sock