57 lines
2.2 KiB
Markdown
57 lines
2.2 KiB
Markdown
# Runtime and Lifecycle
|
|
|
|
## State
|
|
|
|
Runtime MUST store container metadata on disk so that external tools can consume and act on this information.
|
|
It is recommended that this data be stored in a temporary filesystem so that it can be removed on a system reboot.
|
|
On Linux/Unix based systems the metadata MUST be stored under `/run/opencontainer/containers`.
|
|
For non-Linux/Unix based systems the location of the root metadata directory is currently undefined.
|
|
Within that directory there MUST be one directory for each container created, where the name of the directory MUST be the ID of the container.
|
|
For example: for a Linux container with an ID of `173975398351`, there will be a corresponding directory: `/run/opencontainer/containers/173975398351`.
|
|
Within each container's directory, there MUST be a JSON encoded file called `state.json` that contains the runtime state of the container.
|
|
For example: `/run/opencontainer/containers/173975398351/state.json`.
|
|
|
|
The `state.json` file MUST contain all of the following properties:
|
|
|
|
* **`version`**: (string) is the OCF specification version used when creating the container.
|
|
* **`id`**: (string) is the container's ID.
|
|
This MUST be unique across all containers on this host.
|
|
There is no requirement that it be unique across hosts.
|
|
The ID is provided in the state because hooks will be executed with the state as the payload.
|
|
This allows the hooks to perform cleanup and teardown logic after the runtime destroys its own state.
|
|
* **`pid`**: (int) is the ID of the main process within the container, as seen by the host.
|
|
* **`bundlePath`**: (string) is the absolute path to the container's bundle directory.
|
|
This is provided so that consumers can find the container's configuration and root filesystem on the host.
|
|
|
|
*Example*
|
|
|
|
```json
|
|
{
|
|
"id": "oc-container",
|
|
"pid": 4422,
|
|
"root": "/containers/redis"
|
|
}
|
|
```
|
|
|
|
## Lifecycle
|
|
|
|
### Create
|
|
|
|
Creates the container: file system, namespaces, cgroups, capabilities.
|
|
|
|
### Start (process)
|
|
|
|
Runs a process in a container.
|
|
Can be invoked several times.
|
|
|
|
### Stop (process)
|
|
|
|
Not sure we need that from runc cli.
|
|
Process is killed from the outside.
|
|
|
|
This event needs to be captured by runc to run onstop event handlers.
|
|
|
|
## Hooks
|
|
|
|
See [runtime configuration for hooks](./runtime-config.md)
|