Kontena

Whereas Nomad relies on homeopathic dosages, Kontena (Figure 4) lays it on thick without apology. The company from New York and Helsinki presents its platform as a complete alternative to Kubernetes and also claims an equal feature set. Architecturally, Kontena [4] is similar to Kubernetes in many ways: The Kontena node, which can be bare metal or VMs in a cloud environment, runs the Kontena agent, which is controlled by a central Kontena master instance.

Figure 4: The powerful Kontena is similar in functionality to Kubernetes and Docker Swarm.

Kontena puts several layers over the target nodes: First, it creates a Weave-based overlay network technology [5], allowing all parts of the setup to communicate across hosts, data centers, and networks.

Additionally, Kontena includes a DNS-based service discovery solution that is part of the standard program for container solutions and does the job already described in detail for Nomad with regard to node discovery.

One core component of the software is the Kontena orchestrator, which takes care of distributing different containers to the nodes, in single configuration or as a team, and connecting them to each other accordingly. The Kontena workload model differs very little from that of Kubernetes, Docker Swarm, or most other container solutions.

The number of drivers that can be used to control external products is particularly impressive with Kontena. For example, Kontena has a connection for external storage that supports both physical storage in your own data center and cloud storage services from major cloud providers.

The Weave solution used for the virtual network between containers offers features such as multicast support and the ability to integrate VMs directly with clouds through a peer-to-peer feature. Kontena sees itself as a solution for hybrid environments comprising on-premises services and cloud offerings.

Attention to Detail

The many small functions and the various gimmicks the developers have built in are great fun at Kontena. If you need certificates for your containers, for example, you will be pleased to hear about the built-in connection to Let's Encrypt, which makes child's play of issuing certificates. A complete system for role-based access control (RBAC) makes it possible to apply granular control for access to accounts.

OpenVPN is on board to provide a secure connection over an internal network for customers. Load balancers, which are included with almost all container administrators, can be flexibly configured in Kontena (e.g., as SSL terminators), and they also enable rolling updates in combination with various other services.

The possibilities to integrate your applications into accounts in the form of containers are also extensive. Anyone using Docker Compose has an interface in Kontena to which Compose can dock directly. Application definitions can also be imported manually. Once an application is available in Kontena, the environment automatically scales it horizontally as required on the basis of various parameters.

Stacks based on running applications are also possible: These are ready-made, pre-packaged, and reusable collections of services (i.e., a kind of template). For example, anyone who has successfully assembled a web server setup in Kontena from individual parts can make a stack out of it and reproduce the setup as often as desired.

Good Connection to the Outside

The connection to external services is also exemplary: In addition to APIs, which are available as a matter of course, Kontena integrates various monitoring tools, as well as classic logging solutions such as fluentd or StatsD. Anyone who needs an audit trail for compliance reasons will also receive it free of charge in Kontena. Your own image registry, in combination with a very extensive web user interface (UI), complete the offer.

Kontena itself is free; however, you can purchase various support packages from the manufacturer, some of which also include deployment on your own infrastructure, as well as training and business support. Details can be found on the website [4].