core-extra/docs/services.md

# CORE Services

* Table of Contents
{:toc}

## Services

CORE uses the concept of services to specify what processes or scripts run on a
node when it is started. Layer-3 nodes such as routers and PCs are defined by
the services that they run.

Services may be customized for each node, or new custom services can be
created. New node types can be created each having a different name, icon, and
set of default services. Each service defines the per-node directories,
configuration files, startup index, starting commands, validation commands,
shutdown commands, and meta-data associated with a node.

**NOTE:**
   Network namespace nodes do not undergo the normal Linux boot process
   using the **init**, **upstart**, or **systemd** frameworks. These
   lightweight nodes use configured CORE *services*.

### Default Services and Node Types

Here are the default node types and their services:

* *router* - zebra, OSFPv2, OSPFv3, and IPForward services for IGP
  link-state routing.
* *host* - DefaultRoute and SSH services, representing an SSH server having a
  default route when connected directly to a router.
* *PC* - DefaultRoute service for having a default route when connected
  directly to a router.
* *mdr* - zebra, OSPFv3MDR, and IPForward services for
  wireless-optimized MANET Designated Router routing.
* *prouter* - a physical router, having the same default services as the
  *router* node type; for incorporating Linux testbed machines into an
  emulation.

Configuration files can be automatically generated by each service. For
example, CORE automatically generates routing protocol configuration for the
router nodes in order to simplify the creation of virtual networks.

To change the services associated with a node, double-click on the node to
invoke its configuration dialog and click on the *Services...* button,
or right-click a node a choose *Services...* from the menu.
Services are enabled or disabled by clicking on their names. The button next to
each service name allows you to customize all aspects of this service for this
node. For example, special route redistribution commands could be inserted in
to the Quagga routing configuration associated with the zebra service.

To change the default services associated with a node type, use the Node Types
dialog available from the *Edit* button at the end of the Layer-3 nodes
toolbar, or choose *Node types...* from the  *Session* menu. Note that
any new services selected are not applied to existing nodes if the nodes have
been customized.

The node types are saved in a **~/.core/nodes.conf** file, not with the
**.imn** file. Keep this in mind when changing the default services for
existing node types; it may be better to simply create a new node type. It is
recommended that you do not change the default built-in node types. The
**nodes.conf** file can be copied between CORE machines to save your custom
types.

### Customizing a Service

A service can be fully customized for a particular node. From the node's
configuration dialog, click on the button next to the service name to invoke
the service customization dialog for that service.
The dialog has three tabs for configuring the different aspects of the service:
files, directories, and startup/shutdown.

**NOTE:**
   A **yellow** customize icon next to a service indicates that service
   requires customization (e.g. the *Firewall* service).
   A **green** customize icon indicates that a custom configuration exists.
   Click the *Defaults* button when customizing a service to remove any
   customizations.

The Files tab is used to display or edit the configuration files or scripts that
are used for this service. Files can be selected from a drop-down list, and
their contents are displayed in a text entry below. The file contents are
generated by the CORE daemon based on the network topology that exists at
the time the customization dialog is invoked.

The Directories tab shows the per-node directories for this service. For the
default types, CORE nodes share the same filesystem tree, except for these
per-node directories that are defined by the services. For example, the
**/var/run/quagga** directory needs to be unique for each node running
the Zebra service, because Quagga running on each node needs to write separate
PID files to that directory.

**NOTE:**
   The **/var/log** and **/var/run** directories are
   mounted uniquely per-node by default.
   Per-node mount targets can be found in **/tmp/pycore.nnnnn/nN.conf/**
   (where *nnnnn* is the session number and *N* is the node number.)

The Startup/shutdown tab lists commands that are used to start and stop this
service. The startup index allows configuring when this service starts relative
to the other services enabled for this node; a service with a lower startup
index value is started before those with higher values. Because shell scripts
generated by the Files tab will not have execute permissions set, the startup
commands should include the shell name, with
something like ```sh script.sh```.

Shutdown commands optionally terminate the process(es) associated with this
service. Generally they send a kill signal to the running process using the
*kill* or *killall* commands. If the service does not terminate
the running processes using a shutdown command, the processes will be killed
when the *vnoded* daemon is terminated (with *kill -9*) and
the namespace destroyed. It is a good practice to
specify shutdown commands, which will allow for proper process termination, and
for run-time control of stopping and restarting services.

Validate commands are executed following the startup commands. A validate
command can execute a process or script that should return zero if the service
has started successfully, and have a non-zero return value for services that
have had a problem starting. For example, the *pidof* command will check
if a process is running and return zero when found. When a validate command
produces a non-zero return value, an exception is generated, which will cause
an error to be displayed in the Check Emulation Light.

**TIP:**
   To start, stop, and restart services during run-time, right-click a
   node and use the *Services...* menu.

### Creating new Services

Services can save time required to configure nodes, especially if a number
of nodes require similar configuration procedures. New services can be
introduced to automate tasks.

The easiest way to capture the configuration of a new process into a service
is by using the **UserDefined** service. This is a blank service where any
aspect may be customized. The UserDefined service is convenient for testing
ideas for a service before adding a new service type.

To introduce new service types, a **myservices/** directory exists in the
user's CORE configuration directory, at **~/.core/myservices/**. A detailed
**README.txt** file exists in that directory to outline the steps necessary
for adding a new service. First, you need to create a small Python file that
defines the service; then the **custom_services_dir** entry must be set
in the **/etc/core/core.conf** configuration file. A sample is provided in
the **myservices/** directory.

**NOTE:**
   The directory name used in **custom_services_dir** should be unique and
   should not correspond to
   any existing Python module name. For example, don't use the name **subprocess**
   or **services**.

If you have created a new service type that may be useful to others, please
consider contributing it to the CORE project.

Here is an example service with documentation describing functionality:
[Example Service](exampleservice.html)

### Available Services

#### BIRD Internet Routing Daemon
The [BIRD Internet Routing Daemon](https://bird.network.cz/) is a routing daemon; i.e., a software responsible for managing kernel packet forwarding tables. It aims to develop a dynamic IP routing daemon with full support of all modern routing protocols, easy to use configuration interface and powerful route filtering language, primarily targeted on (but not limited to) Linux and other UNIX-like systems and distributed under the GNU General Public License. BIRD has a free implementation of several well known and common routing and router-supplemental protocols, namely RIP, RIPng, OSPFv2, OSPFv3, BGP, BFD, and NDP/RA. BIRD supports IPv4 and IPv6 address families, Linux kernel and several BSD variants (tested on FreeBSD, NetBSD and OpenBSD). BIRD consists of bird daemon and birdc interactive CLI client used for supervision.

In order to be able to use the BIRD Internet Routing Protocol, you must first install the project on your machine.


##### BIRD Package Install
```shell
sudo apt-get install bird
```

##### BIRD Source Code Install
You can download BIRD source code from it's [official repository.](https://gitlab.labs.nic.cz/labs/bird/)
```shell
./configure
make
su
make install
vi /etc/bird/bird.conf
```
The installation will place the bird directory inside */etc* where you will also find its config file.

In order to be able to do use the Bird Internet Routing Protocol, you must modify *bird.conf* due to the fact that the given configuration file is not configured beyond allowing the bird daemon to start, which means that nothing else will happen if you run it. Keeran Marquis has a very detailed example on [Configuring BGP using Bird on Ubuntu](https://blog.marquis.co/configuring-bgp-using-bird-on-ubuntu-14-04lts/) which can be used as a building block to implement your custom routing daemon.


#### FRRouting
FRRouting is a routing software package that provides TCP/IP based routing services with routing protocols support such as BGP, RIP, OSPF, IS-IS and more. FRR also supports special BGP Route Reflector and Route Server behavior. In addition to traditional IPv4 routing protocols, FRR also supports IPv6 routing protocols. With an SNMP daemon that supports the AgentX protocol, FRR provides routing protocol MIB read-only access (SNMP Support).

FRR currently supports the following protocols:
* BGP
* OSPFv2
* OSPFv3
* RIPv1
* RIPv2
* RIPng
* IS-IS
* PIM-SM/MSDP
* LDP
* BFD
* Babel
* PBR
* OpenFabric
* EIGRP (alpha)
* NHRP (alpha)

##### FRRouting Package Install
```shell
sudo apt install curl
curl -s https://deb.frrouting.org/frr/keys.asc | sudo apt-key add -
FRRVER="frr-stable"
echo deb https://deb.frrouting.org/frr $(lsb_release -s -c) $FRRVER | sudo tee -a /etc/apt/sources.list.d/frr.list
sudo apt update && sudo apt install frr frr-pythontools
```

##### FRRouting Source Code Install
Building FRR from source is the best way to ensure you have the latest features and bug fixes. Details for each supported platform, including dependency package listings, permissions, and other gotchas, are in the developer’s documentation. 

FRR’s source is available on the project [GitHub page](https://github.com/FRRouting/frr).
```shell
git clone https://github.com/FRRouting/frr.git
```

Change into your FRR source directory and issue:
```shell
./bootstrap.sh
```
Then, choose the configuration options that you wish to use for the installation. You can find these options on FRR's [official webpage](http://docs.frrouting.org/en/latest/installation.html). Once you have chosen your configure options, run the configure script and pass the options you chose:
```shell
./configure \
    --prefix=/usr \
    --enable-exampledir=/usr/share/doc/frr/examples/ \
    --localstatedir=/var/run/frr \
    --sbindir=/usr/lib/frr \
    --sysconfdir=/etc/frr \
    --enable-pimd \
    --enable-watchfrr \
    ...
```
After configuring the software, you are ready to build and install it in your system.
```shell
make && sudo make install
```
If everything finishes successfully, FRR should be installed.

#### Docker
Docker service allows running docker containers within CORE nodes.
The running of Docker within a CORE node allows for additional extensibility to
the CORE services. This allows network applications and protocols to be easily
packaged and run on any node.

This service will add a new group to the services list. This will have a service called Docker which will just start the docker service within the node but not run anything. It will also scan all docker images on the host machine. If any are tagged with 'core' then they will be added as a service to the Docker group. The image will then be auto run if that service is selected.

This requires a recent version of Docker. This was tested using a PPA on Ubuntu with version 1.2.0. The version in the standard Ubuntu repo is to old for this purpose (we need --net host).

##### Docker Installation
To use Docker services, you must first install the Docker python image. This is used to interface with Docker from the python service.

```shell
sudo apt-get install docker.io
sudo apt-get install python-pip
pip install docker-py
```
Once everything runs successfully, a Docker group under services will appear. An example use case is to pull an image from [Docker](https://hub.docker.com/). A test image has been uploaded for this purpose:
```shell
sudo docker pull stuartmarsden/multicastping
```
This downloads an image which is based on Ubuntu 14.04 with python and twisted. It runs a simple program that sends a multicast ping and listens and records any it receives. In order for this to appear as a docker service it must be tagged with core.
Find out the id by running 'sudo docker images'. You should see all installed images and the one you want looks like this:
```shell
stuartmarsden/multicastping    latest              4833487e66d2        20 hours
ago        487 MB
```
The id will be different on your machine so use it in the following command:
```shell
sudo docker tag 4833487e66d2 stuartmarsden/multicastping:core
```
This image will be listed in the services after we restart the core-daemon:
```shell
sudo service core-daemon restart
```