Today we will deep dive into the linux utility nsenter and we will enter a kubernetes node with it, without using ssh or any other middleware.

Introduction to NSEnter

So, what is nsenter? From nsenter(1):

NAME
       nsenter - run program in different namespaces

SYNOPSIS
       nsenter [options] [program [arguments]]

DESCRIPTION
       The nsenter command executes program in the namespace(s) that are specified in the command-line options (described below). If program is not given, then "${SHELL}" is run (default: /bin/sh).

The nsenter is a handy tool for entering into any given linux namespace. As you might know, a linux namespace is a sandboxing technology used for isolating different aspects of a program. The list of namespaces are as follows, taken from namespaces(7).

You may need to set some specifications to forward custom headers, if you are using stock ingress controller for your cluster.

apiVersion: v1
kind: ConfigMap
metadata:
  name: ingress-nginx-controller
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: "ingress-nginx"
    app.kubernetes.io/instance: "ingress-nginx"
    app.kubernetes.io/component: "controller"
    app.kubernetes.io/part-of: "ingress-nginx"
    app.kubernetes.io/version: "1.12.3"
data:
  use-forwarded-headers: "true"
  proxy-real-ip-cidr: "10.0.0.0/8" # Replace with your trusted CIDR
  compute-full-forwarded-for: "true"
  enable-real-ip: "true"
  allow-snippet-annotations: "true"

use-forwarded-headers

If true, NGINX passes the incoming X-Forwarded-* headers to upstreams. Use this option when NGINX is behind another L7 proxy / load balancer that is setting these headers.

One of the most useful features of Helm is the ability to store state, which allows you not only to expand charts, but also to carefully delete them, clearing away all traces of their presence… However, it’s a good idea to understand exactly how Helm stores the state, which is what we will do in this article.

Introduction

I was just interested in learning how Helm stores state. Understanding this issue is not difficult and everything is cleared in the documentation. As of Helm 3, state is kept secret by default.