# Clixon Restconf

### Installation using Nginx

Ensure www-data is member of the CLICON_SOCK_GROUP (default clicon). If not, add it:
```
  sudo usermod -a -G clicon www-data
```

This implementation uses FastCGI, see http://www.mit.edu/~yandros/doc/specs/fcgi-spec.html.

Download and start nginx. For example on ubuntu:
```
  sudo apt install ngnix
```

Define nginx config file: /etc/nginx/sites-available/default
```
server {
  ...
  location /restconf {
     fastcgi_pass unix:/www-data/fastcgi_restconf.sock;
     include fastcgi_params;
  }
}
```

Start nginx daemon
```
sudo /etc/init.d nginx start
```
Alternatively, start it via systemd:
```
sudo /etc/init.d/nginx start
sudo systemctl start start.service
```

Start clixon restconf daemon
```
olof@vandal> sudo su -c "/www-data/clixon_restconf -f /usr/local/etc/example.xml " -s /bin/sh www-data
```

Make restconf calls with curl
```
olof@vandal> curl -G http://127.0.0.1/restconf/data/interfaces
[
  {
    "interfaces": {
      "interface":[
        {
          "name": "eth0",
          "type": "eth",
          "enabled": "true",
          "name": "eth9",
          "type": "eth",
          "enabled": "true"
         }
      ]
    }
  }
]
olof@vandal> curl -G http://127.0.0.1/restconf/data/interfaces/interface/name=eth9/type
[
  {
    "type": "eth" 
  }
]

curl -sX POST -d '{"interfaces":{"interface":{"name":"eth1","type":"eth","enabled":"true"}}}' http://localhost/restconf/data
```

### Event streams

Clixon have two experimental restconf event stream implementations following
RFC8040 Section 6 using SSE.  One native and one using Nginx
nchan. The two variants to subscribe to the stream is described in the
next section.

The example [../../example/README.md] creates and EXAMPLE stream.

Set the Clixon configuration options if they differ from default values - if they are OK you do not need to modify them:
```
<CLICON_STREAM_PATH>streams</CLICON_STREAM_PATH>
<CLICON_STREAM_URL>https://example.com</CLICON_STREAM_URL>
<CLICON_STREAM_PUB>http://localhost/pub</CLICON_STREAM_PUB>
```
where
- https://example.com/streams is the public fronting subscription base URL. A specific stream NAME can be accessed as https://example.com/streams/NAME
- http://localhost/pub is the local internal base publish stream.

You access the streams using curl, but they differ slightly in behaviour as described in the following two sections.

### Native event streams 

Add the following to extend the nginx configuration file with the following statements:
```
	location /streams {
	    fastcgi_pass unix:/www-data/fastcgi_restconf.sock;
	    include fastcgi_params;
 	    proxy_http_version 1.1;
	    proxy_set_header Connection "";
        }
```

You access a native stream as follos:
```
   curl -H "Accept: text/event-stream" -s -X GET http://localhost/streams/EXAMPLE
   curl -H "Accept: text/event-stream" -s -X GET http://localhost/streams/EXAMPLE?start-time=2014-10-25T10%3A02%3A00Z&stop-time=2014-10-25T12%3A31%3A00Z
```
where the first command retrieves only new notifications, and the second receives a range of messages.

### Nginx Nchan streams

Nginx uses pub/sub channels and can be configured in a variety of
ways. The following uses a simple variant with one generic subscription
channel (streams) and one publication channel (pub). 

Configure clixon with `--enable-publish` which enables curl code for publishing streams to nchan.

Download and install nchan, see (https://nchan.io/#install).

Add the following to extend the nginx configuration file with the following statements:
```
        location ~ /streams/(\w+)$ {
            nchan_subscriber;
            nchan_channel_id $1; #first capture of the location match
        }
        location ~ /pub/(\w+)$ {
            nchan_publisher;
            nchan_channel_id $1; #first capture of the location match
        }        
```

Access the event stream EXAMPLE using curl:
```
   curl -H "Accept: text/event-stream" -s -X GET http://localhost/streams/EXAMPLE
   curl -H "Accept: text/event-stream" -H "Last-Event-ID: 1539961709:0" -s -X GET http://localhost/streams/EXAMPLE
```
where the first command retrieves the whole stream history, and the second only retreives the most recent messages given by the ID.

See (https://nchan.io/#eventsource) on more info on how to access an SSE sub endpoint.

### Debugging

Start the restconf fastcgi program with debug flag:
```
sudo su -c "/www-data/clixon_restconf -D 1 -f /usr/local/etc/example.xml" -s /bin/sh www-data
```
Look at syslog:
```
tail -f /var/log/syslog | grep clixon_restconf
```

Send command:
```
curl -G http://127.0.0.1/restconf/data/*
```

You can also run restconf in a debugger.
```
sudo gdb /www-data/clixon_restconf
(gdb) run -D 1 -f /usr/local/etc/example.xml
```
but you need to ensure /www-data/fastcgi_restconf.sock has the following access:
```
rwxr-xr-x 1 www-data www-data 0 sep 22 11:46 /www-data/fastcgi_restconf.sock
```