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After upgrading Docker to version 20.10 on CentOS 8 and Fedora 33 we can see that it fails to start docker.service. In docker.service logs and firewalld.service logs we can see following message: ERROR: ZONE_CONFLICT: 'docker0' already bound to a zone Solution for this issue: sudo firewall-cmd --zone=trusted --remove-interface=docker0 sudo firewall-cmd --zone=trusted --remove-interface=docker0 --permanent
Example Jenkins Pipeline for building, testing and running Docker containers. Ingredients: • Jenkinsfile - Pipeline specification • GitHub - source code repository (for app and Jenkinsfile) • DockerHub - container registry Required Jenkins plugins: • GitHub plugin • Docker Commons Plugin • Build With Parameters • Pipeline plugin Pipeline architecture schema:
Template for deploying Nextcloud containerized service using Docker and docker-compose, you can use in on both x86_64 and ARM (32/64bit) architecture: https://github.com/openterprise/docker/blob/master/docker-compose-nextcloud.yml This template deploys Nextcloud with following setup: • application: Nextcloud • application server: Apache + PHP • database: MariaDB / PostgreSQL • cache: Redis • scheduler: crontab Requirements: • Docker • docker-compose
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
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'