Docker Environment Setup (CentOS) sudo yum install -y yum-utils sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo sudo yum install -y docker-ce docker-ce-cli containerd.io sudo systemctl enable --now docker Workspace and Configuration Layout mkdir -p /opt/ci/...
1. Persisting Firewall Port Rules When exposing services to external traffic, port configurations must survive system reboots. Using firewalld, rules are applied to the runtime environment by default. To make them permanent, append the --permanent flag: sudo firewall-cmd --zone=public --add-port=808...
Overview of OpenSearch OpenSearch is an open-source, distributed search and analytics suite derived from a fork of Elasticsearch. It supports use cases such as full-text search, log and infrastructure monitoring, security analytics, and operational observability. The project is maintained under the...
Clear any existing container runtime installations: sudo yum remove -y docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine docker-ce docker-ce-cli containerd.io Install necessary dependencies and configure the repository: sudo...
Docker's core value lies in virtualization, or more specifically, environment isolation. Through virtualization technology, Docker implements virtual environments that solve dependency issues in configuration and deployment, enabling decoupling. My understanding of virtualization comes from "O...
Docker leverages specific Linux kernel features to provide an isolated and resource-managed environment for applications. Key among these are Namespaces and Cgroups. Namespaces are responsible for isolating resources like CPU, memory, and network, ensuring that containers operate independently witho...
Understanding Docker's Build Cache Mechanism Docker's caching mechanism significantly optimizes image builds by reusing unchanged layers, which reduces storage requirements and build times. However, effectively utilizing this cache requires understanding its behavior and limitations. Cache Behavior...
Recently I needed to write a new business module that closely resembled one I had written two years ago in Go. I initially planned to adopt the old code, but it turned out to be too tightly coupled to its original context. Small modificasions wouldn’t cut it, so I decided to refactor the core logic....
System Prerequisites Verification Prior to installation, verify the operating system release to ensure compatibility, as Docker requires a CentOS 7 environment or newer. This can be checked using the following command: lsb_release -a Additionally, the system architecture must be 64-bit with a kernel...
When building Docker images, there are scenarios where you need to copy files from a Docker container to the host machine's external enviroment. This is commonly required for extracting data, configuraton files, or other artifacts produced inside a container. This article explains how to copy files...