Managing network connections in container environments


Without a Sidecar

The Traefik mesh works differently. Precisely because the proxy was there at the beginning as the first service with native Kubernetes support, it was obvious to drill it down to a mesh. Anyone who wants to use Traefik as a mesh will not roll out one sidecar per pod with the application in question in Kubernetes, but one Kubernetes proxy per physical host. Ultimately, the admin has no direct influence on the numbers per host when deploying the containers anyway if you roll out the proxy as a native Kubernetes resource.

In practice, this setup leads to a changed communication matrix as soon as the developer of an application configures it to use the proxy server. Each application then communicates with other services in other pods and on other hosts through the centralized Traefik Proxy on each host. The overhead caused by multiple proxy servers per server is eliminated, as is the additional configuration overhead caused by modified pod definitions. Another practical feature, especially for debugging purposes, is that the original communication paths to the individual apps are retained in the various pods. The address on which apps and users contact a service essentially decides whether or not communication is routed by way of Traefik Proxy.

In Traefik, the developers' attention to detail is noticeable in many places. You will regularly find admins and developers cursing because it is difficult to search for or even find errors in dynamic, interwoven mesh environments. In the meantime, therefore, a separate class of tools has established itself on the market to facilitate this task: tracing tools such as Jaeger.

However, for Jaeger to work as a sniffer dog, it needs a communication interface to plug into the ongoing exchange between all the components. Traefik Proxy provides such an interface, making debugging much easier for developers. Additionally, Traefik Proxy integrates easily with a range of monitoring applications focused on modern infrastructure. Interfaces for Prometheus (Figure 4) or InfluxDB are also available out of the box. Even for the open source version of Traefik, this results in comprehensive monitoring capability along with the admin's good feeling of knowing what is going on in their environment.

Figure 4: Traefik Proxy provides interfaces for metrics data to various solutions such as Prometheus or InfluxDB, where the data can then be displayed graphically in Grafana [4]. © Nick Babcock

Mesh environments also benefit from the other features available in Traefik Proxy, including dynamic detection of new instances of individual services, instances that have been dropped in the meantime, and configurable rate limiting so as not to overuse individual instances of individual services.

Traefik Pilot

Traefik turns out to be a proxy that can be used in a mesh context, with the versatile solution significantly reducing complexity (e.g., compared with Istio). Nevertheless, the developers attach great importance to keeping the construct transparent and understandable for the admin. Even without additional components like Jaeger, admins and developers always need to be aware of the state of Traefik.

For this purpose, the developers launched Traefik Pilot (Figure 5): in essence, a GUI for monitoring and supervising Traefik. It uses its interfaces for data acquisition, draws monitoring and trending information from the acquired metrics data, and visualizes the results. Moreover, Traefik instances can be controlled directly in Pilot (e.g., to use Traefik's plugin interface). Traefik Pilot lets you extend Traefik with additional features that are not included by the vendor.

Figure 5: Traefik Pilot is the monitoring solution for Traefik, launched by the manufacturer. © Traefik

Traefik Enterprise

Finally, I'll look at the commercial version of Traefik, Traefik Enterprise, which is aimed at enterprises that want to use Traefik on a large scale and for whom the feature set of the open source variant is not sufficient.

For developers, this is always like riding on a cannonball: On the one hand, many companies from the container environment attach importance to offering open source software and belonging to the open source community. On the other hand, increasing numbers of solutions are becoming established on the market in which even very basic functions are only available in the commercial version. Traefik manages to find a sensible middle ground. Traefik Proxy itself as well as the mesh solution based on it are open source software and can be used without a bill from Traefik. The situation is different with Traefik Pilot, which is only available for cash and not as an open source application.

For some features that Traefik reserves exclusively for the Enterprise variant, it can also be argued that they are actually necessary for regular operation in the year 2021. If you want to connect Traefik to any form of external identity data management (e.g., LDAP or OAuth 2), you will need the commercial version of the software. The factory-installed functions for backup and restore as well as a compatibility interface to conventional environments are also reserved for the commercial variant. However, at least backups can be handled in some other way.

All in all, Traefik does not yet fall into the category of open source pretender. However, the manufacturer follows the bad habit of not clearly naming horse and rider in terms of pricing on its website. What Traefik charges enterprise customers depends on the number of proxies and the level of critical infrastructure – in other words, how subjectively important the particular proxy is to the admin, according to the vendor's statement.

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