runc

command module
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Published: Oct 14, 2019 License: Apache-2.0 Imports: 30 Imported by: 0

README

[![Build Status](https://jenkins.dockerproject.org/buildStatus/icon?job=runc Master)](https://jenkins.dockerproject.org/job/runc Master)

runc

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

Releases

runc depends on and tracks the runtime-spec repository. We will try to make sure that runc and the OCI specification major versions stay in lockstep. This means that runc 1.0.0 should implement the 1.0 version of the specification.

You can find official releases of runc on the release page.

Building

runc currently supports the Linux platform with various architecture support. It must be built with Go version 1.6 or higher in order for some features to function properly.

# create a 'github.com/opencontainers' in your GOPATH/src
cd github.com/opencontainers
git clone https://github.com/opencontainers/runc
cd runc

make
sudo make install

runc will be installed to /usr/local/sbin/runc on your system.

In order to enable seccomp support you will need to install libseccomp on your platform. If you do not want to build runc with seccomp support you can add BUILDTAGS="" when running make.

Build Tags

runc supports optional build tags for compiling support of various features. To add build tags to the make option the BUILDTAGS variable must be set.

make BUILDTAGS='seccomp apparmor'
Build Tag Feature Dependency
seccomp Syscall filtering libseccomp
selinux selinux process and mount labeling
apparmor apparmor profile support libapparmor

Running the test suite

runc 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 TESTFLAGS variable.

# make test TESTFLAGS="-run=SomeTestFunction"

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 export 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 config.json file inside your bundle. runc provides a spec 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 run that will handle creating, starting, and deleting the container after it exits.

cd /mycontainer

runc run mycontainerid

If you used the unmodified runc spec template this should give you a sh session inside the container.

The second way to start a container is using the specs lifecycle operations. This gives you move power of 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 config.json to remove the terminal setting for the simple examples here. Your process field in the config.json should look like this below with "terminal": false and "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": [
                        "CAP_AUDIT_WRITE",
                        "CAP_KILL",
                        "CAP_NET_BIND_SERVICE"
                ],
                "rlimits": [
                        {
                                "type": "RLIMIT_NOFILE",
                                "hard": 1024,
                                "soft": 1024
                        }
                ],
                "noNewPrivileges": true
        },

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

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 adds more complexity but allows higher level systems to manage runc and provides points in the containers creation to setup various settings after the container has created and/or before it is deleted. This is commonly used to setup the container's network stack after create but before start where the user's defined process will be running.

Supervisors

runc 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.pid mycontainerid
ExecStopPost=/usr/local/sbin/runc delete mycontainerid
WorkingDirectory=/mycontainer
PIDFile=/run/mycontainerid.pid

[Install]
WantedBy=multi-user.target

Documentation

The Go Gopher

There is no documentation for this package.

Directories

Path Synopsis
Godeps
_workspace/src/github.com/coreos/go-systemd/activation
Package activation implements primitives for systemd socket activation.
Package activation implements primitives for systemd socket activation.
_workspace/src/github.com/coreos/go-systemd/dbus
Integration with the systemd D-Bus API.
Integration with the systemd D-Bus API.
_workspace/src/github.com/coreos/go-systemd/util
Package util contains utility functions related to systemd that applications can use to check things like whether systemd is running.
Package util contains utility functions related to systemd that applications can use to check things like whether systemd is running.
_workspace/src/github.com/docker/go-units
Package units provides helper function to parse and print size and time units in human-readable format.
Package units provides helper function to parse and print size and time units in human-readable format.
_workspace/src/github.com/godbus/dbus
Package dbus implements bindings to the D-Bus message bus system.
Package dbus implements bindings to the D-Bus message bus system.
_workspace/src/github.com/godbus/dbus/introspect
Package introspect provides some utilities for dealing with the DBus introspection format.
Package introspect provides some utilities for dealing with the DBus introspection format.
_workspace/src/github.com/godbus/dbus/prop
Package prop provides the Properties struct which can be used to implement org.freedesktop.DBus.Properties.
Package prop provides the Properties struct which can be used to implement org.freedesktop.DBus.Properties.
_workspace/src/github.com/golang/protobuf/proto
Package proto converts data structures to and from the wire format of protocol buffers.
Package proto converts data structures to and from the wire format of protocol buffers.
_workspace/src/github.com/seccomp/libseccomp-golang
Package seccomp provides bindings for libseccomp, a library wrapping the Linux seccomp syscall.
Package seccomp provides bindings for libseccomp, a library wrapping the Linux seccomp syscall.
_workspace/src/github.com/syndtr/gocapability/capability
Package capability provides utilities for manipulating POSIX capabilities.
Package capability provides utilities for manipulating POSIX capabilities.
_workspace/src/github.com/urfave/cli
Package cli provides a minimal framework for creating and organizing command line Go applications.
Package cli provides a minimal framework for creating and organizing command line Go applications.
_workspace/src/github.com/vishvananda/netlink
Package netlink provides a simple library for netlink.
Package netlink provides a simple library for netlink.
_workspace/src/github.com/vishvananda/netlink/nl
Package nl has low level primitives for making Netlink calls.
Package nl has low level primitives for making Netlink calls.
Package libcontainer provides a native Go implementation for creating containers with namespaces, cgroups, capabilities, and filesystem access controls.
Package libcontainer provides a native Go implementation for creating containers with namespaces, cgroups, capabilities, and filesystem access controls.
criurpc
Package criurpc is a generated protocol buffer package.
Package criurpc is a generated protocol buffer package.
integration
integration is used for integration testing of libcontainer
integration is used for integration testing of libcontainer
specconv
Package specconv implements conversion of specifications to libcontainer configurations
Package specconv implements conversion of specifications to libcontainer configurations

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