Container

Not Docker! In the C4 model, a container represents an application or a data store. A container is something that needs to be running in order for the overall software system to work. In real terms, a container is something like:

• Server-side web application: A Java EE web application running on Apache Tomcat, an ASP.NET MVC application running on Microsoft IIS, a Ruby on Rails application running on WEBrick, a Node.js application, etc.
• Client-side web application: A JavaScript application running in a web browser using Angular, Backbone.JS, jQuery, etc.
• Client-side desktop application: A Windows desktop application written using WPF, an OS X desktop application written using Objective-C, a cross-platform desktop application written using JavaFX, etc.
• Mobile app: An Apple iOS app, an Android app, a Microsoft Windows Phone app, etc.
• Server-side console application: A standalone (e.g. “public static void main”) application, a batch process, etc.
• Serverless function: A single serverless function (e.g. Amazon Lambda, Azure Function, etc).
• Database: A schema or database in a relational database management system, document store, graph database, etc such as MySQL, Microsoft SQL Server, Oracle Database, MongoDB, Riak, Cassandra, Neo4j, etc.
• Blob or content store: A blob store (e.g. Amazon S3, Microsoft Azure Blob Storage, etc) or content delivery network (e.g. Akamai, Amazon CloudFront, etc).
• File system: A full local file system or a portion of a larger networked file system (e.g. SAN, NAS, etc).
• Shell script: A single shell script written in Bash, etc.
• etc¹