Docker on mac vs linux

Published on 20 Apr 2020

🐳Docker is different on Mac and Linux systems. Docker directly leverages the kernel of the host system on Linux. On the other hand, Mac does not provide a Linux kernel, so Docker runs on a small Linux VM running on a mac. Due to this, there are many differences.

Cannot access container IPs directly

On Linux let’s try to inspect a running docker image :

ubuntu@primary:~$ sudo docker ps
CONTAINER ID        IMAGE               COMMAND              CREATED             STATUS              PORTS               NAMES
a230855dd7d2        httpd               "httpd-foreground"   17 seconds ago      Up 16 seconds       80/tcp              determined_saha
ubuntu@primary:~$ sudo docker inspect determined_saha

Let’s curl the IP :

                   "IPAddress": "172.17.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:02",
                    "DriverOpts": null
                }
            }
        }
    }
]
ubuntu@primary:~$ curl 172.17.0.2
<html><body><h1>It works!</h1></body></html>

However on mac when hitting the IP address of the container we get :

➜ curl 172.17.0.3
curl: (7) Failed to connect to 172.17.0.3 port 80: Operation timed out

Curl times out because the container is running inside the VM and not sharing the network with the mac.