Major Description
Ability to upgrade dockerized yarn native services.
Ref: YARN-5637
Background
Container upgrade is supported by the NM via reInitializeContainer api. reInitializeContainer does NOT change the ContainerId of the upgraded container.
NM performs the following steps during reInitializeContainer:
- kills the existing process
- cleans up the container
- launches another container with the new ContainerLaunchContext
NOTE: ContainerLaunchContext holds all the information that needs to upgrade the container.
With reInitializeContainer, the following does NOT change
- container ID. This is not created by NM. It is provided to it and here RM is not creating another container allocation.
- localizedResources this stays the same if the upgrade does NOT require additional resources IIUC.
The following changes with reInitializeContainer
- the working directory of the upgraded container changes. It is NOT a relaunch.
Changes required in the case of docker container
- reInitializeContainer seems to not be working with Docker containers. Investigate and fix this.
- [Future change] Add an additional api to NM to pull the images and modify reInitializeContainer to trigger docker container launch without pulling the image first which could be based on a flag.
- When the service upgrade is initialized, we can provide the user with an option to just pull the images on the NMs.
- When a component instance is upgrade, it calls the reInitializeContainer with the flag pull-image set to false, since the NM will have already pulled the images.