As the need for greater agility and portability drives the growth of containerization within enterprises world-wide, container orchestration tools have become increasingly important. With multiple nodes running multiple containers, enterprises now need a way to manage and deploy containers at scale. This is where orchestration is valuable. Orchestration is the ability to manage and automatically schedule container deployments onto nodes. Tools like Docker Swarm, a scalable Docker engine clustering solution, and Docker Compose, a powerful tool for deploying multi-container applications, help make orchestration seriously easy for users. These Docker native tools are the industry’s top orchestration solutions for Dockerized environments.
On January 26th, we hosted a webinar on how Docker Orchestration works. Watch the recorded webinar here:
Mike Coleman, Technical Marketing Engineer, answers questions the audience posted during the webinar.
Q: Can you list the supported “out-of-the-box” drivers for Docker Machine?
Docker Machine is able to provision Docker Hosts on a wide variety of platforms: everything from local laptops and desktops using VirtualBox or Fusion, to virtualized machines in your data center running vSphere or Hyper-V, to a wide variety of cloud providers.
You can find a full list of supported drivers (as well as their respective command line syntax) here.
Q: Can swarm spawn host also? Or only containers?
Swarm only handles the placement of containers on existing hosts. The instantiation of new hosts can be handled via a variety of other mechanisms including Docker Machine or capabilities of your underlying infrastructure provider.
Q. Is Docker Swarm scalable?
Absolutely. At DockerCon EU 2015, we showed Swarm scaling to 1,000 nodes and 50,000 containers with 99% of containers deployed in 400ms or less. We are currently scale testing Swarm even further.
Q: What happens if master goes down? can you promote a node as a new master?
From the Docker documentation (where you can also read about how to enable Swarm HA):
The High Availability feature allows a Docker Swarm to gracefully handle the failover of a manager instance. Using this feature, you can create a single primary manager instance and multiple replica instances.
A primary manager is the main point of contact with the Docker Swarm cluster. You can also create and talk to replica instances that will act as backups. Requests issued on a replica are automatically proxied to the primary manager. If the primary manager fails, a replica takes away the lead. In this way, you always keep a point of contact with the cluster.
Q: How does Docker Compose handle the order in which containers are deployed?
Docker Compose will inspect the compose file, and figure out the interdepencies between the containers, and start them in the appropriate order. For instance, if an application has a web front end that talks to a database, it will start the database server before the web server.
Q: Could you compare UCP vs Tutum vs Mesos vs other?
While there are a handful of functional differences between UCP and Tutum (for instance, Tutum can deploy Docker hosts, where the initial release of UCP will not), the main difference is that Tutm is a SaaS platform, and UCP is deployed “on prem” – either in your virtual private cloud or your data center.
Comparing UCP and Tutum to the ever-growing list of orchestration players is too broad of a topic for this Q & A. However, I will say that both Tutum and UCP use Docker’s native API’s to manage your infrastructure. This means that you can use their respective web UI’s in addition to the native Docker CLI you’re used to today. This is not the case with other solutions like Mesos and Kubernetes.
Q. Is a Dockerfile the same as a Docker Compose file?
No, they are two different things. A Dockerfile tells developers how an image should be built. A Compose file (.yaml file) is what is used to deploy multi-container applications. These two are not mutually exclusive.
Q: Can you link Tutum to a private cloud?
Absolutely, provided that you have the right firewall rules in place to allow for the traffic from your data center and Tutum to flow freely, Tutum’s “Bring your own node” functionality will allow you to manage supported Linux-based Docker hosts in your data center.
Q: What are the plans with the regards to the future of Docker Compose files and Tutum stack files?
We’re evaluating the plans around how to reconcile the two file formats, but don’t have anything solid we can talk about today. Stay tuned.
Q: How are the ports exposed with Docker Universal Control Plane when you create 10 nodes of of a given container (e.g. redis) that need to be accessed by another service?
For both UCP and Swarm you’ll need to front end those containers with some sort of proxy. The proxy will present a single IP address to any services that need to access to the containers, as well as routing incoming request.
Interlock is a very popular container-based solution for just this type thing. Interlock is a dynamic, event-driven Docker plugin system using Swarm that has built-in support for both HAProxy and Nginx.
Q: Can I install Docker Universal Control Plane on VMware vSphere?
Yes. Docker Universal Control Plane is a series of Docker containers, so you can install it on any Docker host that meets the system requirements (final system requirements will be documented when UCP releases)
Q: How do you install and run Docker Universal Control Plane?
Docker Universal Control Plane is comprised of a handful of containers that provide various pieces of functionality. It’s installed by executing a single command line, and answering a few straight-forward questions.
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