Book Image

Learning Docker - Second Edition

By : Vinod Singh, Pethuru Raj, Jeeva S. Chelladhurai
Book Image

Learning Docker - Second Edition

By: Vinod Singh, Pethuru Raj, Jeeva S. Chelladhurai

Overview of this book

Docker is an open source containerization engine that offers a simple and faster way for developing and running software. Docker containers wrap software in a complete filesystem that contains everything it needs to run, enabling any application to be run anywhere – this flexibily and portabily means that you can run apps in the cloud, on virtual machines, or on dedicated servers. This book will give you a tour of the new features of Docker and help you get started with Docker by building and deploying a simple application. It will walk you through the commands required to manage Docker images and containers. You’ll be shown how to download new images, run containers, list the containers running on the Docker host, and kill them. You’ll learn how to leverage Docker’s volumes feature to share data between the Docker host and its containers – this data management feature is also useful for persistent data. This book also covers how to orchestrate containers using Docker compose, debug containers, and secure containers using the AppArmor and SELinux security modules.
Table of Contents (13 chapters)

The docker ps command

The docker ps command, which is available inside the container, is used to see the status of the process. This is similar to the standard ps command in the Linux environment and is not a docker ps command that we run on the Docker 
host machine.

This command runs inside the Docker container:

root@5562f2f29417:/# ps -s
UID PID PENDING BLOCKED IGNORED CAUGHT STAT TTY TIME COMMAND
0 1 00000000 00010000 00380004 4b817efb Ss
? 0:00 /bin/bash

0 33 00000000 00000000 00000000 73d3fef9 R+ ? 0:00 ps -s
root@5562f2f29417:/# ps -l
F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD
4 S 0 1 0 0 80 0 - 4541 wait ? 00:00:00 bash
root@5562f2f29417:/# ps -t
PID TTY STAT TIME COMMAND
1 ? Ss 0:00 /bin/bash
35 ? R+ 0:00 ps -t
root@5562f2f29417:/# ps -m
PID TTY TIME CMD
1 ...