Building Microservices with Go

Union filesystem

To keep our images efficient and compact Docker uses the concept of a Union File System. The Union filesystem allows us to represent a logical file system by grouping different directories and or files together. It uses a Copy on Write technique, which copies the layer when we modify the file system, this way we only use about 1MB of space when creating a new image. When data is written to the file system Docker copies the layer and puts it on the top of the stack. When building images and extending existing images we are leveraging this technique, also when starting an image and creating a container the only difference is this writable layer, which means we do not need to copy all the layers every time and fill up our disk. ...