Docker For Mac Docker Subnet
Any Docker for Mac user here? I'm trying to deploy multiple services from a docker-compose.yml file that are sharing the same user-defined bridge network (this is from the mailcow-dockerized config). Services are communicating with each-others just fine, but they can't reach internet.
-->In addition to leveraging the default 'nat' network created by Docker on Windows, users can define custom container networks. User-defined networks can be created using the Docker CLI docker network create -d <NETWORK DRIVER TYPE> <NAME> command. On Windows, the following network driver types are available:
nat – containers attached to a network created with the 'nat' driver will be connected to an internal Hyper-V switch and receive an IP address from the user-specified (
--subnet) IP prefix. Port forwarding / mapping from the container host to container endpoints is supported.Note
NAT networks created on Windows Server 2019 (or above) are no longer persisted after reboot.
Multiple NAT networks are supported if you have the Windows 10 Creators Update installed (or above).
transparent – containers attached to a network created with the 'transparent' driver will be directly connected to the physical network through an external Hyper-V switch. IPs from the physical network can be assigned statically (requires user-specified
--subnetoption) or dynamically using an external DHCP server.Note
Due to the following requirement, connecting your container hosts over a transparent network is not supported on Azure VMs.
Requires: When this mode is used in a virtualization scenario (container host is a VM) MAC address spoofing is required.
overlay - when the docker engine is running in swarm mode, containers attached to an overlay network can communicate with other containers attached to the same network across multiple container hosts. Each overlay network that is created on a Swarm cluster is created with its own IP subnet, defined by a private IP prefix. The overlay network driver uses VXLAN encapsulation. Can be used with Kubernetes when using suitable network control planes (e.g. Flannel).
Requires: Make sure your environment satisfies these required prerequisites for creating overlay networks.
Requires: On Windows Server 2019, this requires KB4489899.
Requires: On Windows Server 2016, this requires KB4015217.
Note
On Windows Server 2019, overlay networks created by Docker Swarm leverage VFP NAT rules for outbound connectivity. This means that a given container receives 1 IP address. It also means that ICMP-based tools such as
pingorTest-NetConnectionshould be configured using their TCP/UDP options in debugging situations.l2bridge - similar to
transparentnetworking mode, containers attached to a network created with the 'l2bridge' driver will be connected to the physical network through an external Hyper-V switch. The difference in l2bridge is that container endpoints will have the same MAC address as the host due to Layer-2 address translation (MAC re-write) operation on ingress and egress. In clustering scenarios, this helps alleviate the stress on switches having to learn MAC addresses of sometimes short-lived containers. L2bridge networks can be configured in 2 different ways:- L2bridge network is configured with the same IP subnet as the container host
- L2bridge network is configured with a new custom IP subnet
In configuration 2 users will need to add a endpoint on the host network compartment that acts as a gateway and configure routing capabilities for the designated prefix.
Requires: Requires Windows Server 2016, Windows 10 Creators Update, or a later release.
l2bridge - similar to
transparentnetworking mode, containers attached to a network created with the 'l2bridge' driver will be connected to the physical network through an external Hyper-V switch. The difference in l2bridge is that container endpoints will have the same MAC address as the host due to Layer-2 address translation (MAC re-write) operation on ingress and egress. In clustering scenarios, this helps alleviate the stress on switches having to learn MAC addresses of sometimes short-lived containers. L2bridge networks can be configured in 2 different ways:- L2bridge network is configured with the same IP subnet as the container host
- L2bridge network is configured with a new custom IP subnet
In configuration 2 users will need to add a endpoint on the host network compartment that acts as a gateway and configure routing capabilities for the designated prefix.
Tip
More details on how to configure and install l2bridge can be found here.
l2tunnel - Similar to l2bridge, however this driver should only be used in a Microsoft Cloud Stack (Azure). Packets coming from a container are sent to the virtualization host where SDN policy is applied.
Network topologies and IPAM
The table below shows how network connectivity is provided for internal (container-to-container) and external connections for each network driver.
Networking modes/Docker drivers
| Docker Windows Network Driver | Typical uses | Container-to-container (Single node) | Container-to-external (single node + multi-node) | Container-to-container (multi-node) |
|---|---|---|---|---|
| NAT (Default) | Good for Developers |
| Routed through Management vNIC (bound to WinNAT) | Not directly supported: requires exposing ports through host |
| Transparent | Good for Developers or small deployments |
| Routed through container host with direct access to (physical) network adapter | Routed through container host with direct access to (physical) network adapter |
| Overlay | Good for multi-node; required for Docker Swarm, available in Kubernetes |
| Not directly supported - requires second container endpoint attached to NAT network on Windows Server 2016 or VFP NAT rule on Windows Server 2019. | Same/Cross Subnet: Network traffic is encapsulated using VXLAN and routed through Mgmt vNIC |
| L2Bridge | Used for Kubernetes and Microsoft SDN |
| Container MAC address re-written on ingress and egress |
|
| L2Tunnel | Azure only | Same/Cross Subnet: Hair-pinned to physical host's Hyper-V virtual switch to where policy is applied | Traffic must go through Azure virtual network gateway | Same/Cross Subnet: Hair-pinned to physical host's Hyper-V virtual switch to where policy is applied |
IPAM
IP Addresses are allocated and assigned differently for each networking driver. Windows uses the Host Networking Service (HNS) to provide IPAM for the nat driver and works with Docker Swarm Mode (internal KVS) to provide IPAM for overlay. All other network drivers use an external IPAM.
| Networking Mode / Driver | IPAM |
|---|---|
| NAT | Dynamic IP allocation and assignment by Host Networking Service (HNS) from internal NAT subnet prefix |
| Transparent | Static or dynamic (using external DHCP server) IP allocation and assignment from IP addresses within container host's network prefix |
| Overlay | Dynamic IP allocation from Docker Engine Swarm Mode managed prefixes and assignment through HNS |
| L2Bridge | Static IP allocation and assignment from IP addresses within container host's network prefix (could also be assigned through HNS) |
| L2Tunnel | Azure only - Dynamic IP allocation and assignment from plugin |
Service Discovery
Service Discovery is only supported for certain Windows network drivers.
| Local Service Discovery | Global Service Discovery | |
|---|---|---|
| nat | YES | YES with Docker EE |
| overlay | YES | YES with Docker EE or kube-dns |
| transparent | NO | NO |
| l2bridge | NO | YES with kube-dns |
The platform known as Docker has become one of the most popular ways to run a new kind of software known as containerized apps. And while Docker's mainly aimed at programmer types, there are a few reasons why everyday Mac users might want it around as well.
What are containerized apps?
Containerized apps are tidy little packages of software that bundle nearly everything they need to run in a single, self-contained box.
Programmers can write an app once and know that it'll run anywhere, every time. Businesses get an efficient way to run lots of apps on a single server without straining their hardware. And users get apps that won't sprawl out and spread files into their hard drives' nooks and crannies, nor start hogging memory and slowing down the entire computer.
How does Docker work?
Docker uses emulation to ensure that the same containerized app can run on any machine where Docker's installed. And because it emulates an operating system – usually some flavor of Linux, though you can also set it up to run enterprise versions of Windows – instead of actual chip hardware, it demands a lot less memory and processing power than traditional virtual machines like Parallels or VMware Fusion.
Unlike those apps, you can't use Docker to run Windows on your Mac – though you can run at least limited versions of Linux with it. And you can use Docker to run apps that weren't originally written for the Mac.
Once you fire up the easy-to-install Docker app, it runs in the background, and you can use the Terminal or another app called Kitematic (we'll get to that later) to install and run containerized apps.
Who is Docker for?
As mentioned above, Docker's mainly aimed at programmers who want to containerize existing apps or write new ones, and businesses and IT folks who want to use its industrial-grade software.
There are Docker versions of familiar desktop apps like Firefox, Chrome, Skype, Spotify, image editor GiMP, and audio editor Audacity. But most of these apps already have native Mac versions. Running them in containers only makes sense if you like the technical challenge, want to keep a single app from hogging all your system's memory, or want to ensure that any malware you might pick up while browsing the web stays stuck inside its container, unable to escape to the rest of your Mac.
As of this writing, the main reason I've found to run Docker on a Mac is Pi-hole, originally made for the Raspberry Pi. Pi-hole can automatically block Web ads across your entire home network, and Docker's the only way to get it working on a Mac without also having a Raspberry Pi.
How to install Docker on your Mac
1. Create a Docker Hub account
Docker Hub keeps track of the containers you're running (or creating) and provides a one-stop shop to find new ones. Sign up for a Docker account with a unique Docker ID, your email, and a strong password.
2. Download Docker Desktop for Mac
Once you've signed up and signed in to Docker Hub, get Docker Desktop for Mac. It's got everything you'll need to run Docker in one Mac-friendly installer. Your Mac needs to be running Mac OS Sierra or later, and have at least 4GB of RAM.
3. Install Docker Desktop on your Mac
Open the docker.dmg file you downloaded, and drag the Docker app's cartoon whale icon into your Applications folder.
4. Open and run Docker
When you run the Docker app, a little whale icon will appear on the right side of the menubar atop your screen. It'll take a few minutes to get running, and Docker may ask your permission to use services on your computer. The app will also prompt you to enter the Docker ID and password you just created.
When containers stop appearing and disappearing atop the little whale icon in the menubar, and you see a green dot at the top of the Docker menu next to 'Docker Desktop is running,' you're all set.
Consult the Preferences in the Docker menu to control how big a chunk of your hard drive Docker's allotted, and how much of your memory and CPU it's allowed to use, among other options.
5. Download and install Kitematic
Kitematic lets you install, manage, and remove your Docker containers from a single graphical interface — a lifesaver if you're not familiar or comfortable with the Terminal. You can install, and later open, Kitematic directly from the Docker app's menu:
Follow the link in that dialog box to install Kitematic. The app may ask for — you guessed it — your Docker ID and password again, just to keep track of your containers.
From Kitematic, you can search for and install new containers, and delete, edit, stop, or restart existing ones. If a container's running, Kitematic gives you an easy way to view its log files, which aren't readily visible from the Terminal. Anyconnect vpn client is not compatible with parallels desktop for mac free. The interface is fairly intuitive, so feel free to play around and see what you can do.
In my tests, Kitematic came in most useful for deleting troublesome containers whose installation I'd somehow botched. Just find the container in the list on the left side of the Kitematic window, click the X icon next to it, and the container's gone completely, for good. You can always reinstall a package, either from the Terminal or by searching for it in Kitematic, and try again.
Where can I learn more about Docker for Mac?
Consult Docker for Mac's help files for more information about getting started, ways to test that your installation's up and running smoothly, and more things you can do with Docker. There's also a guide to teach you how to create your own containerized apps.
For less technically inclined folks, it's tough to find a good list of desktop apps that work with Docker. Docker Hub doesn't break desktop apps into their own category, but Jessie Frazelle compiled this list in 2015.
Besides Pi-hole, do you have any favorite Docker containers that might benefit everyday Mac users? Ship them our way in the comments below.
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