---
title: Calico Repositories
canonical_url: 'https://docs.projectcalico.org/v3.5/reference/repo-structure'
---

## The calico-containers repository

This respository contains the following:

- `calico/node`: the Docker image used to run the Calico Felix agent
  (responsible for IP routing and ACL programming) and a BIRD BGP agent (for
  distributing routes between hosts).  See [`calico_node` directory]({{site.baseurl}}/{{page.version}}/reference/architecture)
  for details.
- `calicoctl`: the command line tool used for starting a `calico/node`
  container, configuring Calico policy, adding and removing containers in a
  Calico network via orchestration tools, and managing certain network and
  diagnostic administration.  See [`calicoctl` directory]({{site.baseurl}}/{{page.version}}/reference/calicoctl) for
  implementation of calicoctl.  This directory also contains a `calico/build`
  Docker image which is used to build the `calicoctl` binary.
- UTs testing calicoctl, STs testing single host and multihost systems
  using calicoctl and calico/node to create Calico networked containers.  These
  tests run within the `calico/test` Docker image.
  for the UT and ST codebase.  Also see the Makefile for
  details on how the STs (`make st`) and UTs (`make ut`) are run using the
  `calico/test` image.
- Release scripts used to validate our documentation and to cut a new branch
  for a specific release.

It pulls together a number of related repositories that provide subsets of
function for running Calico in a containerized environment.  These related
respositories are listed below.

## Calico Libraries

 - [calico](https://github.com/projectcalico/calico): This repo contains the
   implementation of Felix which is the heart of Calico networking.  Felix
   interfaces with the Linux kernel to configure routes and ACLs
   that control network policy connectivity. In `calico/node`, Felix runs as a
   separate process.  It is installed directly into the `calico/node` image.

 - [libcalico](https://github.com/projectcalico/libcalico): Contains a variety
   of helper methods and classes for manipulating the Calico data in an etcd
   datastore, IP address management and useful namespace utilities to
   manipulating container interfaces.  The libcalico library is used by
   `calicoctl`.  It is imported as a standard Python library into the
   `calicoctl` Python codebase.  libcalico also contains the `calico/test` Docker
   image used for running both UTs and STs testing Calico with Docker.

## Calico Orchestrator Integration Plugins

There are several integrations available for Calico in a containerized
environment.  The repositories below hold the plugin code for these
integrations.

 - [calico-mesos](https://github.com/projectcalico/calico-mesos): Implements
   the Calico plugin for running Calico with the [mesos](https://github.com/apache/mesos)
   orchestrator.  This plugin may be installed manually (from a binary attached
   to a relase), or as an RPM which can be created.

 - [calico-cni](https://github.com/projectcalico/calico-cni): Implements the
   Calico plugin for running Calico with any orchestrator that uses the
   [Container Network Interface](https://github.com/appc/cni), including [rkt](https://github.com/coreos/rkt)
   and [Kubernetes](https://github.com/kubernetes/kubernetes)

 - [libnetwork-plugin](https://github.com/projectcalico/libnetwork-plugin):
   Implements Calico plugin support for the (libnetwork based) Docker
   networking plugin.  It provides both network and IPAM drivers which may
   be used when creating networks through Docker. When calico/node is started with the
   `--libnetwork` flag, it will also run the libnetwork plugin inside the same container.
