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opencontainers /runc

CLI tool for spawning and running containers according to the OCI specification

7.1K Stars 1.3K Forks Last release: about 1 month ago (v1.0.0-rc91) Apache License 2.0 4.5K Commits 24 Releases

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is a CLI tool for spawning and running containers according to the OCI specification.



depends on and tracks the runtime-spec repository. We will try to make sure that


and the OCI specification major versions stay in lockstep. This means that


1.0.0 should implement the 1.0 version of the specification.

You can find official releases of


on the release page.

Currently, the following features are not considered to be production-ready:


The reporting process and disclosure communications are outlined here.

Security Audit

A third party security audit was performed by Cure53, you can see the full report here.



currently supports the Linux platform with various architecture support. It must be built with Go version 1.13 or higher.

In order to enable seccomp support you will need to install


on your platform.



for CentOS, or


for Ubuntu

# create a '' in your GOPATH/src cd git clone cd runc make sudo make install

You can also use

go get

to install to your


, assuming that you have a

parent folder already created under



go get cd $GOPATH/src/ make sudo make install

will be installed to


on your system.

Build Tags


supports optional build tags for compiling support of various features, with some of them enabled by default (see


in top-level



To change build tags from the default, set the


variable for make, e.g.

make BUILDTAGS='seccomp apparmor'

| Build Tag | Feature | Enabled by default | Dependency | |-----------|------------------------------------|--------------------|------------| | seccomp | Syscall filtering | yes | libseccomp | | selinux | selinux process and mount labeling | yes | | | apparmor | apparmor profile support | yes | | | nokmem | disable kernel memory accounting | no | |

Running the test suite


currently supports running its test suite via Docker. To run the suite just type

make test


make test

There are additional make targets for running the tests outside of a container but this is not recommended as the tests are written with the expectation that they can write and remove anywhere.

You can run a specific test case by setting the



# make test TESTFLAGS="-run=SomeTestFunction"

You can run a specific integration test by setting the



# make test TESTPATH="/checkpoint.bats"

You can run a specific rootless integration test by setting the



# make test ROOTLESS\_TESTPATH="/checkpoint.bats"

You can run a test using your container engine's flags by setting





# make test CONTAINER\_ENGINE\_BUILD\_FLAGS="--build-arg http\_proxy=http://yourproxy/" CONTAINER\_ENGINE\_RUN\_FLAGS="-e http\_proxy=http://yourproxy/"

Dependencies Management


uses Go Modules for dependencies management. Please refer to Go Modules for how to add or update new dependencies. When updating dependencies, be sure that you are running Go


or newer.

# Update vendored dependencies make vendor # Verify all dependencies make verify-dependencies

Using runc

Creating an OCI Bundle

In order to use runc you must have your container in the format of an OCI bundle. If you have Docker installed you can use its


method to acquire a root filesystem from an existing Docker container.

# create the top most bundle directory mkdir /mycontainer cd /mycontainer # create the rootfs directory mkdir rootfs # export busybox via Docker into the rootfs directory docker export $(docker create busybox) | tar -C rootfs -xvf -

After a root filesystem is populated you just generate a spec in the format of a


file inside your bundle.


provides a


command to generate a base template spec that you are then able to edit. To find features and documentation for fields in the spec please refer to the specs repository.

runc spec

Running Containers

Assuming you have an OCI bundle from the previous step you can execute the container in two different ways.

The first way is to use the convenience command


that will handle creating, starting, and deleting the container after it exits.

# run as root cd /mycontainer runc run mycontainerid

If you used the unmodified

runc spec

template this should give you a


session inside the container.

The second way to start a container is using the specs lifecycle operations. This gives you more power over how the container is created and managed while it is running. This will also launch the container in the background so you will have to edit the


to remove the


setting for the simple examples here. Your process field in the


should look like this below with

"terminal": false


"args": ["sleep", "5"]


"process": { "terminal": false, "user": { "uid": 0, "gid": 0 }, "args": ["sleep", "5"], "env": ["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", "TERM=xterm"], "cwd": "/", "capabilities": { "bounding": ["CAP\_AUDIT\_WRITE", "CAP\_KILL", "CAP\_NET\_BIND\_SERVICE"], "effective": ["CAP\_AUDIT\_WRITE", "CAP\_KILL", "CAP\_NET\_BIND\_SERVICE"], "inheritable": ["CAP\_AUDIT\_WRITE", "CAP\_KILL", "CAP\_NET\_BIND\_SERVICE"], "permitted": ["CAP\_AUDIT\_WRITE", "CAP\_KILL", "CAP\_NET\_BIND\_SERVICE"], "ambient": ["CAP\_AUDIT\_WRITE", "CAP\_KILL", "CAP\_NET\_BIND\_SERVICE"] }, "rlimits": [{ "type": "RLIMIT\_NOFILE", "hard": 1024, "soft": 1024 }], "noNewPrivileges": true },

Now we can go through the lifecycle operations in your shell.

# run as root cd /mycontainer runc create mycontainerid # view the container is created and in the "created" state runc list # start the process inside the container runc start mycontainerid # after 5 seconds view that the container has exited and is now in the stopped state runc list # now delete the container runc delete mycontainerid

This allows higher level systems to augment the containers creation logic with setup of various settings after the container is created and/or before it is deleted. For example, the container's network stack is commonly set up after


but before



Rootless containers


has the ability to run containers without root privileges. This is called


. You need to pass some parameters to


in order to run rootless containers. See below and compare with the previous version.

Note: In order to use this feature, "User Namespaces" must be compiled and enabled in your kernel. There are various ways to do this depending on your distribution: - Confirm


is set in your kernel configuration (normally found in


) - Arch/Debian:

echo 1 \> /proc/sys/kernel/unprivileged\_userns\_clone
  • RHEL/CentOS 7:
    echo 28633 \> /proc/sys/user/max\_user\_namespaces

Run the following commands as an ordinary user: ```bash

Same as the first example

mkdir ~/mycontainer cd ~/mycontainer mkdir rootfs docker export $(docker create busybox) | tar -C rootfs -xvf -

The --rootless parameter instructs runc spec to generate a configuration for a rootless container, which will allow you to run the container as a non-root user.

runc spec --rootless

The --root parameter tells runc where to store the container state. It must be writable by the user.

runc --root /tmp/runc run mycontainerid ```



can be used with process supervisors and init systems to ensure that containers are restarted when they exit. An example systemd unit file looks something like this.

[Unit] Description=Start My Container [Service] Type=forking ExecStart=/usr/local/sbin/runc run -d --pid-file /run/ mycontainerid ExecStopPost=/usr/local/sbin/runc delete mycontainerid WorkingDirectory=/mycontainer PIDFile=/run/ [Install]

cgroup v2

See [




The code and docs are released under the Apache 2.0 license.

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