#WHAT IS KUBERNETES CONFIGMAP HOW TO#
#WHAT IS KUBERNETES CONFIGMAP FULL#
#WHAT IS KUBERNETES CONFIGMAP CODE#
#WHAT IS KUBERNETES CONFIGMAP FREE#

This means that we want a value with boolean values we need to quote the values, like 'true' or 'false'. The key and values in a ConfigMap can only be strings.

Custom DH parameters for perfect forward secrecy.

NGINX Configuration NGINX Configuration.

Let’s start with a basic purpose: to build a simple REST endpoint that returns a JSON payload like this: mutex.Unlock() case watch.Deleted: mutex. I’m discussing the pattern here in a configmap-specific context, but almost everything I’m going to say after this would apply equally to pods, services, service accounts, etc.

#WHAT IS KUBERNETES CONFIGMAP CODE#

In fact, you could adapt most of the code in this article to work with almost any supported kubernetes resource type. If you’ve ever worked with the kubernetes API, whether directly by writing your own client library or with the client-go library, you may already know that watchers are not remotely configmap-specific. This generates a starting configmap (which we modify during the examples) with a data section looking like this: data: cluster1.endpoint: cluster2.endpoint: cluster3.endpoint: cluster4.endpoint: cluster5.endpoint: current.target: cluster1.endpoint Not just for configmaps Kubectl create cm clusters-config -from-env-file=configs/clusters.properties įor each of these examples, I will be creating the configmap from the root of the above repository with this command:

#WHAT IS KUBERNETES CONFIGMAP FULL#

The full source for the application we’ll be writing is at. With this setup we will have pointing to exper-0. Create a service which will expose this custom nginx deployment.

#WHAT IS KUBERNETES CONFIGMAP FREE#

You are free to copy/use any portion of that code as you see fit. Create a custom nginx deployment with a specific nf injected using a configmap. Where to find the samplesĪll of the samples (both code and configs) I will show here can be found in my GitHub repo at.

#WHAT IS KUBERNETES CONFIGMAP HOW TO#

In this article and a subsequent one, I am going to demonstrate three examples of how to do this - the first, covered here, will be using the standard kubernetes client library for golang, the second and third (to be discussed in the next article in the series) will be using different parts of the knative configmap package I used in part 1. changes to a resource of a given type.įortunately, kubernetes (as noted above) provides support for an event-driven model natively, and using this model for consuming configmaps lets us write code that is not only simpler than that for monitoring changes to a file, but also more robust and fault-tolerant. Has it gotten bigger or smaller, or has a computed checksum changed, for example? In an event-driven model, the client takes more of a passive role - “I’d like to hear about any events, you just let me know when they occur.” This lets us write simpler, lighter code and focus on the problems that we really care about, not on how to detect e.g. Whereas monitoring a file for changes is more of a monitoring problem - the watching code has to know the state of the file, then essentially poll the file for any changes. The kubelet keeps the mount updated (with some slight delay, up to two minutes in a default configuration), and you can certainly monitor files within the mount filesystem for changes just as you would any other file.īut one of the core patterns that using kubernetes (and even more so with knative in the mix) encourages is event-driven programming. The client code monitoring such a resource is thus the watcher here, and in the following discussion I am going to show some specific examples of using watchers to handle configmaps much more dynamically than is generally possible when consuming them via volume mounts.īefore we go any further, let me make clear that you absolutely can implement a watcher for a mounted configmap. Kubernetes API resources all support a watch feed, which allows API clients to monitor resources in which they are interested, be informed of changes, and then act accordingly (in whatever manner they wish). In this post, I am going to discuss a specific strategy for handling configmaps, namely, using a watcher. In my previous post, Working with kubernetes configmaps, part 1: volume mounts, I discussed the mechanisms for loading kubernetes configmaps from volume mounts within a container, and how the method used to create a configmap would translate into how the data would be presented.

What is kubernetes configmap