Web Application for Docker
Docker is a open source toll designed to make it easier to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package . All that is needed for programs distributed through Docker is inside the image and does not intersect with the primary system and other containers.
In a way, Docker is a bit like a virtual machine. But unlike a virtual machine, rather than creating a whole virtual operating system, Docker allows applications to use the same Linux kernel as the system that they’re running on and only requires applications be shipped with things.
Docker is a tool that is designed to benefit both developers and system administrators, making it a part of many DevOps (developers + operations) toolchains.
Developing a Web Application for Docker:
The Common Gateway Interface, or CGI, is a set of standards that define how information is exchanged between the web server and a custom script.
To understand the concept of CGI, let us see what happens when we click a hyper link to browse a particular web page or URL.
- Your browser contacts the HTTP web server and demands for the URL, i.e., filename.
- Web Server parses the URL and looks for the filename. If it finds that file then sends it back to the browser, otherwise sends an error message indicating that you requested a wrong file.
- Web browser takes response from web server and displays either the received file or error message.
To Run any program as CGI the following steps to be followed:
- The program file should be in cgi-bin directory
- Make file as executable file. An executable file is a type of computer file that runs a program when it is opened. This means it executes code or a series of instructions contained in the file.
chmod +x <file_name>
- Use of hashbang (#!) indicates that the webpage uses client-side rendering to deliver the right content. A large number of sites use hashbang as they have some useful features which make them great for client-side applications.
- Mention the type of content to be displayed on the client browser.
httpd is the Apache HyperText Transfer Protocol (HTTP) server program. It is designed to be run as a standalone daemon process. When used like this it will create a pool of child processes or threads to handle requests.
The subprocess module is a powerful part of the Python standard library that lets you run external programs and inspect their outputs easily.
Examples of scripted Behavior :
- Loading new webpage content without reloading the page, via Ajax or a Web socket. For example, user of social media can send and receive messages without leaving the current page.
- Web page animations, such as fading objects in and out, resizing, and moving them.
- Playing browser games.
- Controlling the playback of streaming media.
- Generating pop-ups.
- validating input values of a web form before the data is sent to a web server.
- Logging data about the user’s behavior then sending it to a server. The website owner can use this data for analytics , Ad Tracking , and personalization .