Sealer has two top module: Build Engine & Apply Engine
The Build Engine Using Kubefile and build context as input, and build a CloudImage that contains all the dependencies. The Apply Engine Using Clusterfile to init a cluster which contains kubernetes and other applications.
# Build Engine
- Parser : parse Kubefile into image metadata
- Registry : push or pull the CloudImage
- Store : save CloudImage to local disks
- Lite Builder, sealer will check all the manifest or helm chart, decode docker images in those files, and cache them into CloudImage.
- Cloud Builder, sealer will create a Cluster using public cloud, and exec
RUN & CMDcommand which defined in Kubefile, then cache all the docker image in the Cluster.
- Container Builder, Using Docker container as a node, run kubernetes cluster in container then cache all the docker images.
# Apply Engine
- Infra : manage infrastructure, like create VMs in public cloud then apply the cluster on top of it. Or using docker emulation nodes.
- Runtime : cluster installer implementation, like using kubeadm to install cluster.
- Config : application config, like mysql username passwd or other configs, you can use Config overwrite any file you want.
- Plugin : plugin help us do some extra work, like exec a shell command before install, or add a label to a node after install.
- Debug : help us check the cluster is healthy or not, find reason when things unexpected.
# Other modules
- Filesystem : Copy CloudRootfs files to all nodes
- Mount : mount CloudImage all layers together
- Checker : do some pre-check and post check
- Command : a command proxy to do some tasks which os don't have the command. Like ipvs or cert manager.
- Guest : manage user application layer, like exec CMD command defined in Kubefile.