Quick start

This section describes how to run the Hello world example available in source code at: clixon hello example.

Clixon is not a system in itself, it is a support system for an application. In this case, the “application” is hello world. The hello world application is very simple where the application semantics is completely described by a YANG specification and a CLI specification.

A more advanced application will have backend (and frontend) plugins to add application-specific semantics. This is not necessary in the hello world application.

Content

Files relevant to the hello example are:

Compile and run

Before you start, go through the install instructions for your platform.

make && sudo make install

Start backend in the background:

sudo clixon_backend

Start cli:

clixon_cli

Using the CLI

The example CLI allows you to modify and view the data model using set, delete and show via generated code.

The following example shows how to add a very simple configuration hello world using the generated CLI. The config is added to the candidate database, shown, committed to running, and then deleted.

olof@vandal> clixon_cli
cli> set <?>
  hello
cli> set hello world
cli> show configuration
hello world;
cli> commit
cli> delete <?>
  all                   Delete whole candidate configuration
  hello
cli> delete hello
cli> show configuration
cli> commit
cli> quit
olof@vandal>

Netconf

Clixon also provides a Netconf interface. The following example starts a netconf client form the shell, adds the hello world config, commits it, and shows it:

olof@vandal> clixon_netconf -q
<rpc><edit-config><target><candidate/></target><config><hello xmlns="urn:example:hello"><world/></hello></config></edit-config></rpc>]]>]]>
<rpc-reply><ok/></rpc-reply>]]>]]>
<rpc><commit/></rpc>]]>]]>
<rpc-reply><ok/></rpc-reply>]]>]]>
<rpc><get-config><source><running/></source></get-config></rpc>]]>]]>
<rpc-reply><data><hello xmlns="urn:example:hello"><world/></hello></data></rpc-reply>]]>]]>
olof@vandal>

Restconf

Clixon can use two RESTCONF compile-time variants:

  • FCGI : Reverse proxy such as Nginx using an internal FCGI socket communication. A reverse proxy needs to be configured.
  • Native http: web-server using libevhtp. The libevhtp web server is integrated with the clixon restconf daemon and needs no extra installations, apart from ensuring you have server and client certs for https.

FCGI

In the case of the FCGI solution, a reverse proxy such as nginx needs to be installed, and edit config file /etc/nginx/sites-available/default:

server {
   ...
   location / {
      fastcgi_pass unix:/www-data/fastcgi_restconf.sock;
      include fastcgi_params;
   }
   # Enable this for restconf notification streams
   location /streams {
      fastcgi_pass unix:/www-data/fastcgi_restconf.sock;
      include fastcgi_params;
      proxy_http_version 1.1;
      proxy_set_header Connection "";
   }
}

Note that the second part is necessary only for notification streams.

Start nginx daemon:

sudo /etc/init.d/nginx start

or using systemd:

sudo systemctl start nginx.service

Start and run

Regardless of which RESTCONF variant is used, next step is to start the restconf daemon:

sudo /www-data/clixon_restconf

Start sending restconf commands (using Curl):

olof@vandal> curl -X POST http://localhost/restconf/data -d '{"clixon-hello:hello":{"world":null}}'
olof@vandal> curl -X GET http://localhost/restconf/data
{
   "data": {
     "clixon-hello:hello": {
       "world": null
     }
   }
}

Run a container

You can run the hello example as a pre-built docker container, on a x86_64 Linux. See instructions in the clixon docker hello example.

First, the container is started with the backend running:

$ sudo docker run --rm -p 8080:80 --name hello -d clixon/hello

Then a CLI is started

$ sudo docker exec -it hello clixon_cli
cli> set ?
 hello
cli> set hello world
cli> show configuration
hello world;

Or Netconf:

$ sudo docker exec -it clixon/clixon clixon_netconf
<rpc><get-config><source><candidate/></source></get-config></rpc>]]>]]>
<rpc-reply><data/></rpc-reply>]]>]]>

Or using restconf using curl on exposed port 8080:

$ curl -X GET http://localhost:8080/restconf/data/hello:system

Next steps

The hello world example only has a Yang spec and a template CLI spec. For more advanced applications, customized backend, CLI, netconf and restconf code callbacks becomes necessary.

Further, you may want to add upgrade, RPC:s, state data, notification streams, authentication and authorization. The main example contains such capabilities.