How to setup `kubectl krew` inside Docker Container?

I’m trying to use kubectl with krew inside a Docker container. Here’s my Dockerfile:

FROM alpine:latest
ENV KUBECTL_VERSION=v1.30.5 KREW_VERSION=v0.4.4
RUN apk update && apk add --no-cache curl bash git \
    && curl -LO "https://dl.k8s.io/release/${KUBECTL_VERSION}/bin/linux/amd64/kubectl" \
    && chmod +x kubectl && mv kubectl /usr/local/bin/ \
    && curl -fsSL "https://github.com/kubernetes-sigs/krew/releases/download/${KREW_VERSION}/krew-linux_amd64.tar.gz" | tar xz -C /tmp \
    && mv /tmp/krew-* /usr/local/bin/krew \
    && /usr/local/bin/krew install konfig
ENV PATH="/root/.krew/bin:${PATH}"
CMD ["tail", "-f", "/dev/null"]

Steps I followed:

1. Built the image: docker build -t kubectl-krew .
2. Ran the container: docker run -it kubectl-krew
3. Inside the container:
   • kubectl version works and shows:

     Client Version: v1.30.5
     Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
     The connection to the server localhost:8080 was refused - did you specify the right host or port?
     

   • krew version shows:

     OPTION            VALUE
     GitTag            v0.4.4
     GitCommit         343e657
     IndexURI          https://github.com/kubernetes-sigs/krew-index.git
     BasePath          /root/.krew
     IndexPath         /root/.krew/index/default
     InstallPath       /root/.krew/store
     BinPath           /root/.krew/bin
     DetectedPlatform  linux/amd64
     

   • But kubectl krew update fails with:
     error: unknown command "krew" for "kubectl"

Environment variable $PATH is:
/root/.krew/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin.

Why is kubectl krew not recognized? How can I fix this?

HAHA!!! I solved the issue.

If you look at the krew intallation page you will find the instruction to install krew in the Linux. So, I need to run

(
  set -x; cd "$(mktemp -d)" &&
  OS="$(uname | tr '[:upper:]' '[:lower:]')" &&
  ARCH="$(uname -m | sed -e 's/x86_64/amd64/' -e 's/\(arm\)\(64\)\?.*/\1\2/' -e 's/aarch64$/arm64/')" &&
  KREW="krew-${OS}_${ARCH}" &&
  curl -fsSLO "https://github.com/kubernetes-sigs/krew/releases/latest/download/${KREW}.tar.gz" &&
  tar zxvf "${KREW}.tar.gz" &&
  ./"${KREW}" install krew
)

and then finally:

export PATH="${KREW_ROOT:-$HOME/.krew}/bin:$PATH"

So, I included the above changes in my Dockerfile to below:

# Base image
FROM ubuntu:20.04

# Set non-interactive mode for APT
ENV DEBIAN_FRONTEND=noninteractive

# Install dependencies
RUN apt-get update && apt-get install -y \
    curl \
    tar \
    git \
    ca-certificates \
    && apt-get clean

# Install kubectl
RUN curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl" && \
    chmod +x kubectl && \
    mv kubectl /usr/local/bin/

# Install krew
RUN set -x; \
    cd "$(mktemp -d)" && \
    OS="$(uname | tr '[:upper:]' '[:lower:]')" && \
    ARCH="$(uname -m | sed -e 's/x86_64/amd64/' -e 's/\(arm\)\(64\)\?.*/\1\2/' -e 's/aarch64$/arm64/')" && \
    KREW="krew-${OS}_${ARCH}" && \
    curl -fsSLO "https://github.com/kubernetes-sigs/krew/releases/latest/download/${KREW}.tar.gz" && \
    tar zxvf "${KREW}.tar.gz" && \
    ./"${KREW}" install krew && \
    rm -rf "${KREW}.tar.gz" ./"${KREW}"

# Set up PATH for krew
ENV PATH="${KREW_ROOT:-/root/.krew}/bin:$PATH"

# Verify installation
RUN kubectl krew version && kubectl version --client

# Set the entrypoint to keep the container alive
CMD ["tail", "-f", "/dev/null"]

and now when i run kubectl krew version, I get:

OPTION            VALUE
GitTag            v0.4.4
GitCommit         343e657
IndexURI          https://github.com/kubernetes-sigs/krew-index.git
BasePath          /root/.krew
IndexPath         /root/.krew/index/default
InstallPath       /root/.krew/store
BinPath           /root/.krew/bin
DetectedPlatform  linux/amd64