How to use Docker containers for efficient development and testing on Linux?

DockerBuildKit is a modern image building backend. It can improve construction efficiency and maintainability by 1) parallel processing of independent construction steps, 2) more advanced caching mechanisms (such as remote cache reuse), and 3) structured output improves construction efficiency and maintainability, significantly optimizing the speed and flexibility of Docker image building. Users only need to enable the DOCKER_BUILDKIT environment variable or use the buildx command to activate this function.

DockerworkswithDockerDesktopbyprovidingauser-friendlyinterfaceandenvironmenttomanagecontainers,images,andresourcesonlocalmachines.1.DockerDesktopbundlesDockerEngine,CLI,Compose,andothertoolsintoonepackage.2.Itusesvirtualization(likeWSL2onWindowsorHyp

Kubernetes is not a replacement for Docker, but the next step in managing large-scale containers. Docker is used to build and run containers, while Kubernetes is used to orchestrate these containers across multiple machines. Specifically: 1. Docker packages applications and Kubernetes manages its operations; 2. Kubernetes automatically deploys, expands and manages containerized applications; 3. It realizes container orchestration through components such as nodes, pods and control planes; 4. Kubernetes works in collaboration with Docker to automatically restart failed containers, expand on demand, load balancing and no downtime updates; 5. Applicable to application scenarios that require rapid expansion, running microservices, high availability and multi-environment deployment.

The main difference between Docker and traditional virtualization lies in the processing and resource usage of the operating system layer. 1. Docker containers share the host OS kernel, which is lighter, faster startup, and more resource efficiency; 2. Each instance of a traditional VM runs a full OS, occupying more space and resources; 3. The container usually starts in a few seconds, and the VM may take several minutes; 4. The container depends on namespace and cgroups to achieve isolation, while the VM obtains stronger isolation through hypervisor simulation hardware; 5. Docker has better portability, ensuring that applications run consistently in different environments, suitable for microservices and cloud environment deployment.

When encountering Docker problems, you should first locate the problem, which is problems such as image construction, container operation or network configuration, and then follow the steps to check. 1. Check the container log (dockerlogs or docker-composelogs) to obtain error information; 2. Check the container status (dockerps) and resource usage (dockerstats) to determine whether there is an exception due to insufficient memory or port problems; 3. Enter the inside of the container (dockerexec) to verify the path, permissions and dependencies; 4. Review whether there are configuration errors in the Dockerfile and compose files, such as environment variable spelling or volume mount path problems, and recommend that cleanbuild avoid cache dryness

There are three main ways to set environment variables in PHP: 1. Global configuration through php.ini; 2. Passed through a web server (such as SetEnv of Apache or fastcgi_param of Nginx); 3. Use putenv() function in PHP scripts. Among them, php.ini is suitable for global and infrequently changing configurations, web server configuration is suitable for scenarios that need to be isolated, and putenv() is suitable for temporary variables. Persistence policies include configuration files (such as php.ini or web server configuration), .env files are loaded with dotenv library, and dynamic injection of variables in CI/CD processes. Security management sensitive information should be avoided hard-coded, and it is recommended to use.en

There are three common ways to set environment variables in a Docker container: use the -e flag, define ENV instructions in a Dockerfile, or manage them through DockerCompose. 1. Adding the -e flag when using dockerrun can directly pass variables, which is suitable for temporary testing or CI/CD integration; 2. Using ENV in Dockerfile to set default values, which is suitable for fixed variables that are not often changed, but is not suitable for distinguishing different environment configurations; 3. DockerCompose can define variables through environment blocks or .env files, which is more conducive to development collaboration and configuration separation, and supports variable replacement. Choose the right method according to project needs or use multiple methods in combination

To expose Docker container ports, the host needs to access the container service through port mapping. 1. Use the dockerrun-p[host_port]:[container_port] command to run the container, such as dockerrun-p8080:3000my-web-app; 2. Use the EXPOSE instruction to mark the purpose in the Dockerfile, such as EXPOSE3000, but the port will not be automatically published; 3. Configure the ports segment of the yml file in DockerCompose, such as ports:-"8080:3000"; 4. Use dockerps to check whether the port map is generated after running.