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In docker, RunC is a CLI tool that creates and runs containers according to OCI standards. It is a command line tool that follows OCI standards for running containers. runC is the core part of docker. The creation, running, destruction and other operations of the container will eventually be completed by calling runc.
The operating environment of this tutorial: linux5.9.8 system, docker-1.13.1 version, Dell G3 computer.
OCI defines the container runtime standard, and runC is a specific implementation formulated by Docker in accordance with the open container format standard Open Container Format, OCF.
This project is migrated from Docker's libcontainer and implements functions such as container start and stop, resource isolation, etc. Therefore, the container can be run directly through this tool.
The so-called container runtime (Container Runtime) includes container management and container imaging. Open Container Initiative, OCI is the industry standard for container runtime, including:
A) Runtime standard runtime-spec;
B) Container image standard image-spec.
Simply put, the container image standard defines the packaging form of the container image, and the runtime standard defines how to run a container.
RunC is a CLI tool that creates and runs containers according to OCI standards. It is a command line tool for running containers that follows OCI standards. It is also a Runtime implementation.
Docker
In the old version, you need to call docker-runc
, but in the latest CE version, directly Modified to runc
command.
#RunC is the bottom-level running environment of the container, and its upper layer is managed through Docker.
runC is the core part of docker. The creation, running, destruction and other operations of the container will eventually be completed by calling runc.
RunC is the running state of the container and does not include image management. If you use it directly, you need to prepare the image first. Here, you can directly use the already built BusyBox template.
OCI Bundle
OCI Bundle refers to a series of files that meet OCI standards. These files contain all the data needed to run the container. They are stored in a common directory, which contains the following two items:
config.json
Contains the configuration data of the container running; If Docker is installed on the host, you can use the docker export
command to export the existing image into OCI Bundle format.
Generate rootfs
Use the BusyBox template in Docker directly.
Configuration file
In the rootfs
directory, it contains common binary files , in addition to the root directory, a config.json
configuration file is also required, and the configuration template can be generated through the runc spec
command.
For detailed configuration, please refer to https://github.com/opencontainers/runtime-spec/blob/master/spec.md
Change "terminal" in the configuration file: true
is changed to false
, otherwise cannot allocate tty if runc will detach without setting console socket
will be reported when creating.
In addition, because the terminal is closed, the command is modified to "args": [ "sleep", "10000" ],
parameters.
Start
After starting, you can passps aux | grep sleep
See specific commands.
is to perform a CheckPoint operation on a container and obtain a series of files, and then start it on other machines .
Recommended learning: "docker video tutorial"
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