github.com/anuvu/storage@v1.12.13/README.md (about) 1 `storage` is a Go library which aims to provide methods for storing filesystem 2 layers, container images, and containers. A `containers-storage` CLI wrapper 3 is also included for manual and scripting use. 4 5 To build the CLI wrapper, use 'make binary'. 6 7 Operations which use VMs expect to launch them using 'vagrant', defaulting to 8 using its 'libvirt' provider. The boxes used are also available for the 9 'virtualbox' provider, and can be selected by setting $VAGRANT_PROVIDER to 10 'virtualbox' before kicking off the build. 11 12 The library manages three types of items: layers, images, and containers. 13 14 A *layer* is a copy-on-write filesystem which is notionally stored as a set of 15 changes relative to its *parent* layer, if it has one. A given layer can only 16 have one parent, but any layer can be the parent of multiple layers. Layers 17 which are parents of other layers should be treated as read-only. 18 19 An *image* is a reference to a particular layer (its _top_ layer), along with 20 other information which the library can manage for the convenience of its 21 caller. This information typically includes configuration templates for 22 running a binary contained within the image's layers, and may include 23 cryptographic signatures. Multiple images can reference the same layer, as the 24 differences between two images may not be in their layer contents. 25 26 A *container* is a read-write layer which is a child of an image's top layer, 27 along with information which the library can manage for the convenience of its 28 caller. This information typically includes configuration information for 29 running the specific container. Multiple containers can be derived from a 30 single image. 31 32 Layers, images, and containers are represented primarily by 32 character 33 hexadecimal IDs, but items of each kind can also have one or more arbitrary 34 names attached to them, which the library will automatically resolve to IDs 35 when they are passed in to API calls which expect IDs. 36 37 The library can store what it calls *metadata* for each of these types of 38 items. This is expected to be a small piece of data, since it is cached in 39 memory and stored along with the library's own bookkeeping information. 40 41 Additionally, the library can store one or more of what it calls *big data* for 42 images and containers. This is a named chunk of larger data, which is only in 43 memory when it is being read from or being written to its own disk file. 44 45 **[Contributing](CONTRIBUTING.md)** 46 Information about contributing to this project.