Host mode is only available on Linux hosts, not Docker for Mac. That means it is publicly exposed - same IP as the host, different ports. In host mode, a container interface in host mode shares the interface namespace with the host.
Another concern is that back-end networks are implicit security, not explicit, so hard to audit.Ĭontainers can be connected and disconnected from user-define bridges on the fly by the administrator / owner.
The concern is that servers should not be doing routing, as troubleshooting that is a nightmare. I can live with directly-connected back-end networks. Personally, I somewhat prefer servers to have exactly one network connection. By default, no container ports are exposed to the outside world. All container ports on a user-defined bridge are accessible to the other attached containers. However, container names can be used as well as IP addresses. User-defined bridge networks are basically private subnets, private to the containers connected to them (and the host). The host that the containers are running on itself is also connected to the bridge.īy default, containers on a host all connect to the default bridge docker0, and all ports on them are exposed (published) to the outside world. The bridge is associated with a private IP subnet, and attached containers are automatically assigned addresses in that subnet. Bridge Modeīridge mode acts like a virtual switch (single VLAN) for the containers connected to it. Terminology: in the following, “ports” will refer to TCP or UDP ports. Docker Networkingįor more details, see the O’Reilly book and other references below.ĭocker has several “network drivers” or modes: bridge, host, overlay, and macvlan modes. TMI for getting started, we’ll need the big picture first. Note: we won’t worry about the actual implementation mechanism, iptables or whatever. Subsequent blogs may tackle more of them. This blog will try to address some of those items.
#DOCKER NETWORK MONITORING TOOLS SOFTWARE#
How is load balancing being done? Is there a physical / classic load balancer (if you insist: “application delivery controller”) front-ending a software load balancer?.How does traffic get routed to the Kubernetes or other cluster in the first place?.What sort of overlay, if any, does the service mesh use between hosts / nodes?.Which addresses are or are not externally reachable?.How does user traffic reach containers? How do various containerized micro-services reach each other? In response to that, service discovery and / or load balancing is likely being used.Containers may be long-lived but in principle they can come and go, particularly when workload monitoring is being used.What sort of addressing design is used with various container mechanisms? Are containers reached via the node address and TCP port, or which entities running on a node get addresses?.Here’s my current list of things one might want to know: I (and the reader!) have no reason to expect working with containers to be any different. Most recently, forms of teaming in VMware mis-matched to a Nexus VPC. I’ve often enough been in situations where server and hypervisor admins can’t tell me what’s going on in sufficient detail to troubleshoot a problem. Need to Know Checklistįor me, networking, especially network troubleshooting, is all about the flows. Having said that much, and in the interest of keeping the length reasonable, this blog will focus on Docker Networking. For more info, please use the References listed at the end of this blog. I’m not prepared to write one, and if you’re reading this, you’re probably not looking for a blog that long. There are entire books dedicated to this topic. Will you be ready should that happen?Īs a result, I’ll try to give the flavor of container networking, and provide lots of reading references. In the best case, they may ask for the networking team’s design advice. DevOps teams may or may not coordinate well. Manageability and performance may be two related factors. For what it’s worth, some blogs I’ve seen indicate that as use of containers grows and scales up, knowledge of container networking is becoming increasingly critical. I’ve been self-educating on the topic, and I’m finding container networking a complex topic, with variations depending on the tools in use (I’d like a scorecard summary!). If there’s one thing a networking person should probably know about containers, it is of course container networking.
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