Vagrant ping or curl from guest to host machine - ruby-on-rails

Question

I wonder how I can run the command, using the terminal, from my vagrant machine:
$ ping localhost:3000
or
$ curl http://localhost:3000
In host machine (OSX) I have a rails server running in localhost:3000, so I expect something to show in the rails log.

Answer 1

When I run in the VM:
$ ip route show
In the output there is a line like:
default via 10.0.2.2 dev enp0s3 proto static metric 1024
That is the IP to ping from the guest:
curl http://10.0.2.2:3000

Answer 2

Inside the vagrant machine localhost refers to the guest vagrant machine, i.e. localhost doesn't refer to host machine. One way to access host machine from guest is to configure a private network. You can specify a static private IP for vagrant, like this:
Vagrant.configure("2") do |config|
config.vm.network "private_network", ip: "192.168.50.4"
end
After this guest is accessible from host via 192.168.50.4 and host is accessible from guest via 192.168.50.1, i.e. the end octate for host's IP will be 1 inside guest machine.
After vagrant up, you can do this from inside guest machine:
$ ping 192.168.50.1
$ curl http://192.168.50.1:3000
Note that, if you have some strict firewall setup then you have to allow connection from 192.168.50.4.

Answer 3

You can also set network to "public_network" in the guest machine's config file.
In the Vageantfile just uncomment the line:
config.vm.network "public_network"
Restart the machine:
vagrant halt
vagrant up
Do the ip addr show and your ip on the public network is the one listed under eth1 (instead of the usual eth0)