mininet中的Web服务器（nginx）

Question

After using sudo mn to build a simple network in mini-net, I use nginx to build a web server in host1.

I use systemctl start nginx in host1 xterm to build a web server. But it seems it starts a web server on my localhost, not in the mini-net. I cannot access the web server in host1 and host2 by Firefox in mini-net.

Is there anything wrong in my operation?

Answer 1

the reason why you cannot connect to the server on host1 is as you said - the host isn't there it's running on 127.0.0.1 (localhost) of your hosts's machine not any of your mininet hosts.

The way to get around this is by telling nxinx to run on your host's (local) IP explicitly via the server conf file.

Here's an example that works for me. (Tested with nginx 1.4.6, mininet 2.3.0 and ubuntu 18.04)

from mininet.topo import Topo
from mininet.node import CPULimitedHost
from mininet.link import TCLink
from mininet.net import Mininet
import time

class DumbbellTopo(Topo):
    def build(self, bw=8, delay="10ms", loss=0):
        switch1 = self.addSwitch('switch1')
        switch2 = self.addSwitch('switch2')
        appClient = self.addHost('aClient')
        appServer = self.addHost('aServer')
        crossClient = self.addHost('cClient')
        crossServer = self.addHost('cServer')
        self.addLink(appClient, switch1)
        self.addLink(crossClient, switch1)
        self.addLink(appServer, switch2)
        self.addLink(crossServer, switch2)
        self.addLink(switch1, switch2, bw=bw, delay=delay, loss=loss, max_queue_size=14)

def simulate():
    dumbbell = DumbbellTopo()
    network = Mininet(topo=dumbbell, host=CPULimitedHost, link=TCLink, autoPinCpus=True)
    network.start()

    appClient = network.get('aClient')
    appServer = network.get('aServer')

    wd = str(appServer.cmd("pwd"))[:-2]

    appServer.cmd("echo 'b a n a n a s' > available-fruits.html")
    appServer.cmd("echo 'events { } http { server { listen " + appServer.IP() + "; root " + wd + "; } }' > nginx-conf.conf") # Create server config file
    appServer.cmd("sudo nginx -c " + wd + "/nginx-conf.conf &") # Tell nginx to use configuration from the file we just created

    time.sleep(1) # Server might need some time to start

    fruits = appClient.cmd("curl http://" + appServer.IP() + "/available-fruits.html")
    print(fruits)

    appServer.cmd("sudo nginx -s stop")
    network.stop()

if __name__ == '__main__':
    simulate()

This way we create the nginx conf file (nginx-conf.conf), then tell nginx to use this for its configuration.

Alternatively if you want to start it from a terminal on the host, create the conf file and then use the command to tell nginx to run with this file as shown in the code above.