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Working with kernel network namespaces created by Docker

Published on 2020-09-26 Author admin

To work with kernel network namespaces created by Docker create necessary symbolic link: ln -s /var/run/docker/netns /var/run/netns List network namespaces: ip netns list Result will be similar to: # ip netns list 644c14147ad2 (id: 2) bb230cf5f65f (id: 1) e2772d19bfd0 (id: 0) Execute command inside network namespace: ip netns exec <namespace> <command> Example - listing network… Continue reading Working with kernel network namespaces created by Docker →

Running SQL query on database inside Docker container running on remote host

Published on 2020-04-15 Author admin

Single line command to run SQL query on database inside Docker container running on remote host: ssh root@tinkerboard -C 'docker exec -i nextcloud-mariadb mysql -u nextcloud -p -e "SELECT * FROM oc_bruteforce_attempts;" nextcloud'

CentOS 8 and Fedora 32 - make DNS working for Docker containers

Published on 2020-04-01 Author admin

In CentOS 8 and Fedora 32, by default DNS requests from Docker containers are being blocked by Firewalld. To make DNS working for Docker containers use below command (assuming that containers are using docker0 interface for networking): sudo firewall-cmd --zone=trusted --add-interface=docker0 --permanent sudo firewall-cmd --zone=trusted --add-interface=docker0

Running Docker on Fedora 31 - revert systemd configuration to use cgroup v1

Published on 2019-10-31 Author admin

Fedora 31 is first major distro with cgroup v2 (unified hierarchy). Follow below steps to make Docker working on it: Add Docker CE repository: sudo dnf config-manager --add-repo https://download.docker.com/linux/fedora/docker-ce.repo Install Docker CE: sudo dnf install docker-ce When you try to run Docker container on freshly installed Fedora 31, you will get following error message: docker:… Continue reading Running Docker on Fedora 31 - revert systemd configuration to use cgroup v1 →