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)

Webhook notifications

Docker Registry has the in-built capability of sending notifications based on registry activities:

Notifications are sent to the endpoints via HTTP. This complete notification is based on the listener and broadcaster architecture. Each endpoint has its own queue and all actions (push/pull/delete) trigger the events. These events are queued and once the event reaches the end of the queue, it triggers an HTTP request to the endpoint. The events are sent to each endpoint, but the order is not guaranteed.

Events have a well-defined JSON structure and are sent as the body of the notification. One or more events are sent in the structure and are called an envelope. An envelope may contain one or more events. The registry is also capable of receiving responses from endpoints. The responses with 2XX or 3XX response codes are considered as valid responses and consider the message delivered.

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