Better ephemeral workspace support with Codespaces

Signed-off-by: GitHub <noreply@github.com>

developer-workspace/README.md

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+# Ephemeral developer workspaces
+
+Aiming to provide better developer experience when making contributions to kube-prometheus, whether by actively developing new features/bug fixes or by reviewing pull requests, we want to provide ephemeral developer workspaces with everything already configured (as far as tooling makes it possible).
+
+Those developer workspaces should provide a brand new kubernetes cluster, where kube-prometheus can be easily deployed and the contributor can easily see the impact that a pull request is proposing.
+
+Today there is 2 providers in the market:
+* [Github Codespaces](https://github.com/features/codespaces)
+* [Gitpod](https://www.gitpod.io/)
+
+## Codespaces
+
+Unfortunately, Codespaces is not available for everyone. If you are fortunate to have access to it, you can open a new workspace from a specific branch, or even from Pull Requests.
+
+![image](https://user-images.githubusercontent.com/24193764/135522435-44b177b4-00d4-4863-b45b-2db47c8c70d0.png)
+
+![image](https://user-images.githubusercontent.com/24193764/135522560-c64968ab-3b4e-4639-893a-c4d0a14421aa.png)
+
+After your workspace start, you can deploy a kube-prometheus inside a Kind cluster inside by running `make deploy`.
+
+If you are reviewing a PR, you'll have a fully-functional kubernetes cluster, generating real monitoring data that can be used to review if the proposed changes works as described.
+
+If you are working on new features/bug fixes, you can regenerate kube-prometheus's YAML manifests with `make generate` and deploy it again with `make deploy`. 
+
+## Gitpod
+
+Gitpod is already available to everyone to use for free. It can also run commands that we speficy in the `.gitpod.yml` file located in the root directory of the git repository, so even the cluster creation can be fully automated.
+
+You can use the same workflow as mentioned in the [Codespaces](#Codespaces) section, however Gitpod doesn't have native support for any kubernetes distribution. The workaround is to create a full QEMU Virtual Machine and deploy [k3s](https://github.com/k3s-io/k3s) inside this VM. Don't worry, this whole process is already fully automated, but due to the workaround the whole workspace may be very slow.

developer-workspace/codespaces/prepare-kind.sh

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+#!/bin/bash
+
+which kind
+if [[ $? != 0 ]]; then
+    echo 'kind not available in $PATH, installing latest kind'
+    # Install latest kind
+    curl -s https://api.github.com/repos/kubernetes-sigs/kind/releases/latest \
+    | grep "browser_download_url.*kind-linux-amd64" \
+    | cut -d : -f 2,3 \
+    | tr -d \" \
+    | wget -qi -
+    mv kind-linux-amd64 kind && chmod +x kind
+fi
+
+cluster_created=$($PWD/kind get clusters 2>&1)
+if [[ "$cluster_created" == "No kind clusters found." ]]; then 
+    $PWD/kind create cluster
+else
+    echo "Cluster '$cluster_created' already present" 
+fi

developer-workspace/common/deploy-kube-prometheus.sh

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+#!/bin/bash
+
+kubectl apply -f manifests/setup
+
+# Safety wait for CRDs to be working
+sleep 30
+
+kubectl apply -f manifests/
+sleep 30
+# Safety wait for resources to be created
+
+kubectl rollout status -n monitoring daemonset node-exporter
+kubectl rollout status -n monitoring statefulset alertmanager-main
+kubectl rollout status -n monitoring statefulset prometheus-k8s
+kubectl rollout status -n monitoring deployment grafana
+kubectl rollout status -n monitoring deployment kube-state-metrics
+
+kubectl port-forward -n monitoring svc/grafana 3000 > /dev/null 2>&1 &
+kubectl port-forward -n monitoring svc/alertmanager-main 9093 > /dev/null 2>&1 &
+kubectl port-forward -n monitoring svc/prometheus-k8s 9090 > /dev/null 2>&1 &

developer-workspace/gitpod/prepare-k3s.sh

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+#!/bin/bash
+
+script_dirname="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+rootfslock="${script_dirname}/_output/rootfs/rootfs-ready.lock"
+k3sreadylock="${script_dirname}/_output/rootfs/k3s-ready.lock"
+
+if test -f "${k3sreadylock}"; then
+    exit 0
+fi
+
+cd $script_dirname
+
+function waitssh() {
+  while ! nc -z 127.0.0.1 2222; do   
+    sleep 0.1
+  done
+  ./ssh.sh "whoami" &>/dev/null
+  if [ $? -ne 0 ]; then
+    sleep 1
+    waitssh
+  fi
+}
+
+function waitrootfs() {
+  while ! test -f "${rootfslock}"; do
+    sleep 0.1
+  done
+}
+
+echo "🔥 Installing everything, this will be done only one time per workspace."
+
+echo "Waiting for the rootfs to become available, it can take a while, open the terminal #2 for progress"
+waitrootfs
+echo "✅ rootfs available"
+
+echo "Waiting for the ssh server to become available, it can take a while, after this k3s is getting installed"
+waitssh
+echo "✅ ssh server available"
+
+./ssh.sh "curl -sfL https://get.k3s.io | sh -"
+
+mkdir -p ~/.kube
+./scp.sh root@127.0.0.1:/etc/rancher/k3s/k3s.yaml ~/.kube/config
+
+echo "✅ k3s server is ready"
+touch "${k3sreadylock}"
+
+# safety wait for cluster availability
+sleep 30s

developer-workspace/gitpod/prepare-rootfs.sh

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+#!/bin/bash
+
+set -euo pipefail
+
+img_url="https://cloud-images.ubuntu.com/hirsute/current/hirsute-server-cloudimg-amd64.tar.gz"
+
+script_dirname="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+outdir="${script_dirname}/_output/rootfs"
+
+rm -Rf $outdir
+mkdir -p $outdir
+
+curl -L -o "${outdir}/rootfs.tar.gz" $img_url
+
+cd $outdir
+
+tar -xvf rootfs.tar.gz
+
+qemu-img resize hirsute-server-cloudimg-amd64.img +20G
+
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --run-command 'resize2fs /dev/sda'
+
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --root-password password:root
+
+netconf="
+network:
+  version: 2
+  renderer: networkd
+  ethernets:
+    enp0s3:
+      dhcp4: yes
+"
+
+# networking setup
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --run-command "echo '${netconf}' > /etc/netplan/01-net.yaml"
+
+# copy kernel modules
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --copy-in /lib/modules/$(uname -r):/lib/modules
+
+# ssh
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --run-command 'apt remove openssh-server -y && apt install openssh-server -y'
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --run-command "sed -i 's/#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config"
+sudo virt-customize -a hirsute-server-cloudimg-amd64.img --run-command "sed -i 's/PasswordAuthentication no/PasswordAuthentication yes/' /etc/ssh/sshd_config"
+
+# mark as ready
+touch rootfs-ready.lock
+
+echo "k3s development environment is ready"

developer-workspace/gitpod/qemu.sh

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+#!/bin/bash
+
+set -xeuo pipefail
+
+script_dirname="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+outdir="${script_dirname}/_output"
+
+sudo qemu-system-x86_64 -kernel "/boot/vmlinuz" \
+-boot c -m 3073M -hda "${outdir}/rootfs/hirsute-server-cloudimg-amd64.img" \
+-net user \
+-smp 8 \
+-append "root=/dev/sda rw console=ttyS0,115200 acpi=off nokaslr" \
+-nic user,hostfwd=tcp::2222-:22,hostfwd=tcp::6443-:6443 \
+-serial mon:stdio -display none

developer-workspace/gitpod/scp.sh

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+#!/bin/bash
+
+sshpass -p 'root' scp -o StrictHostKeychecking=no -P 2222 $@

developer-workspace/gitpod/ssh.sh

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+#!/bin/bash
+
+sshpass  -p 'root' ssh -o StrictHostKeychecking=no -p 2222 root@127.0.0.1 "$@"