This post will demonstrate how Kubernetes HostPath volumes can help you get access to the Kubernetes nodes. Atleast you can play with the filesystem of the node on which you pod is scheduled on. You can get access to other containers running on the host, certificates of the kubelet, etc. I have a 3-master and 3-node cluster and setup using this script, running in a Vagrant environment. All the nodes are in ready state: ...

It’s always a hassle creating certificates and lot of technical jargons involved. This can be simplified, using mkcert. Install by following one of the steps mentioned in the docs. Once installed just run: $ mkcert -install Created a new local CA at "/home/hummer/.local/share/mkcert" 💥 [sudo] password for hummer: The local CA is now installed in the system trust store! ⚡ The local CA is now installed in the Firefox and/or Chrome/Chromium trust store (requires browser restart)! 🦊 This has installed the local CA. Now all you need to do is create a new certificate. ...

In golang while using struct tag, the spaces make a lot of difference. For example look at the following code. type PodStatus struct { Status string `json: ",status"` } If you run go vet on this piece of code you will get following error: $ go vet types.go # command-line-arguments ./types.go:28: struct field tag `json: ",status"` not compatible with reflect.StructTag.Get: bad syntax for struct tag value Now this does not tell us what is wrong with the struct tag, json: ",status". The problem with this struct tag is that the extra space can be interpreted as delimiter so provide key-value pair without space. ...

How do you access the etcd that is being used by the OpenShift started by oc cluster up or using minishift. If you are using minishift then get docker environment access of the minishift VM by running following commands. eval $(minishift docker-env) && eval $(minishift oc-env) Exec into the container named origin that runs OpenShift and all the needed services. $ docker exec -it origin bash First install the etcdctl needed to talk to etcd. [root@surajd origin]$ yum -y install etcd Get into the directory where all the certs and keys are available. ...

There is no easy way to change namespace in Kubernetes using kubectl command line utility. But here are some commands that you can alias in your bashrc file so that it’s just a single command that you can use to change the namespace in the Kubernetes cluster. Change namespace Let’s see step by step what goes in to change the namespace. So the first step is to find the context. A context element in a kubeconfig file is used to group access parameters under a convenient name. Each context has three parameters: cluster, namespace, and user. By default, the kubectl command-line tool uses parameters from the current context to communicate with the cluster. Read more. ...

This post is very specific to OpenShift and how you can have an application exposing prometheus metrics to be scraped by a prometheus running in the same cluster. Requirements Setting up cluster I have done it using the oc cluster up, read about how to do this here. You could also setup a local OpenShift cluster by running minishift, read about setting up minishift here. Downloading Kedge The configurations defined for setting up this cluster is written in a format that is understood by a tool called Kedge. This makes configuration easier to understand and edit. So for using this setup download Kedge and put it in your path as explained here. ...

Test Fixtures “go test” sets pwd as package directory Test Helpers should never return an error they should access to the *testing.T object call t.Helper() in the beginning (works only for go1.9+) for things reqiuiring clean up return closures Configurability Unconfigurable behavior is often a point of difficulty for tests. e.g. ports, timeouts, paths. Over-parameterize structs to allow tests to fine-tune their behavior It’s ok to make these configs unexported so only tests can set them. Slides Video GopherCon 2017: Mitchell Hashimoto - Advanced Testing with Go by Mitchell Hashimoto

Pointer receiver For a struct User with a method Work with pointer receiver. type User struct { Name string Period int } func (u *User) Work() { fmt.Println(u.Name, "has worked for", u.Period, "hrs.") } func main() { uval := User{"UserVal", 5} uval.Work() pval := &User{"UserPtr", 6} pval.Work() } See on go playground. output: UserVal has worked for 5 hrs. UserPtr has worked for 6 hrs. If we call this method on value type object uval it works, and obviously it works with pointer type object pval. Value receiver Now we change the method receiver from pointer to value. ...

This post has shortcuts that are generic and golang specific as well. This post will edited from time to time. Shortcuts Toggle side bar Ctrl + B Project explorer in side bar Ctrl + Shift + E Project wide search in side bar Ctrl + Shift + F Source control in side bar Ctrl + Shift + G Copy entire line Ctrl + C (without any selection) Delete entire line Ctrl + Shift + K ...

I am doing Kubernetes native development using minikube. And for doing that I had to download a Container image that is available in internally hosted private container registry. On the configuration side of doing that you will need to create Kubernetes Secret of type docker-registry. And now refer that secret you just created in your Pod manifest under pod.spec.imagePullSecrets. For more info follow the tutorial in Kubernetes docs on Pull an Image from a Private Registry. ...