Building k8s prometheus adapter

Building k8s-prometheus-adapter

The instructions provided below specify the steps to build k8s-prometheus-adapter version 0.2.2 on Linux on IBM Z for the following distributions:

• RHEL (7.3, 7.4, 7.5)
• SLES (12 SP3, 15)
• Ubuntu (16.04, 18.04)

Prerequisites

• Docker -- Instructions for install Docker can be found here

General Notes:

• When following the steps below please use a standard permission user unless otherwise specified

• A directory /<source_root>/ will be referred to in these instructions, this is a temporary writable directory anywhere you'd like to place it

Step 1: Install the Dependencies

• RHEL (7.3, 7.4, 7.5)

  sudo yum install -y tar wget gcc git make curl mercurial       
  

• SLES (12 SP3, 15)

  sudo zypper install -y tar wget gcc git make curl mercurial python-devel
  

• Ubuntu (16.04, 18.04)

  sudo apt-get update
  sudo apt-get install -y git make golang golang-1.10 tar curl wget mercurial
  sudo rm -v /usr/bin/go
  sudo ln -s /usr/lib/go-1.10/bin/go /usr/bin/go
  

• Install glide

  wget https://github.com/Masterminds/glide/releases/download/v0.13.1/glide-v0.13.1-linux-s390x.tar.gz
  sudo tar -vxz -f glide-v0.13.1-linux-s390x.tar.gz -C /usr/local/bin --strip=1
  export PATH=$PATH:/usr/local/bin
  

• Install Go (Only for RHEL and SLES) -- Instructions for building Go can be found here.

Step 2: Build and install k8s-prometheus-adapter

• Setup Environment variable and source folder to build the package

  export GOPATH=/<source_root>/
  

• Download k8s-prometheus-adapter source code

  mkdir -p $GOPATH/src/github.com/directxman12
  cd $GOPATH/src/github.com/directxman12
  git clone https://github.com/directxman12/k8s-prometheus-adapter.git
  cd k8s-prometheus-adapter
  git checkout v0.2.2
  

• Build k8s-prometheus-adapter

  cd $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter
  make all ARCH=s390x    
  

Step 3: Testing and verifying(Optional)

• Run test cases

  cd $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter
  make test
  make verify
  

Step 4: Deploy k8s-prometheus-adapter to Kubernetes

• Prerequisites

  • A running Kubernetes cluster.

  • Prometheus -- Instructions to install Prometheus server can be found here.

• Create k8s-prometheus-adapter docker image for s390x

  cd $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter
  make docker-build ARCH=s390x

  Note: make docker-build ARCH=s390x will create directxman12/k8s-prometheus-adapter-s390x:latest which should be tagged directxman12/k8s-prometheus-adapter:0.2.2. The image is tagged 0.2.2 because it fails with a imagePullError issue with tag latest as it always tries to download from the repository instead of checking locally for the image.

• Create namespace custom-metrics to ensure the namespace we choose to install the custom metrics adapter in.

  kubectl create namespace custom-metrics
  

• Create a secret called cm-adapter-serving-certs with two values: serving.crt and serving.key

  cd $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter
  export PURPOSE=serving
  openssl req -x509 -sha256 -new -nodes -days 365 -newkey rsa:2048 -keyout ${PURPOSE}-ca.key -out ${PURPOSE}-ca.crt -subj "/CN=ca"
  echo '{"signing":{"default":{"expiry":"43800h","usages":["signing","key encipherment","'${PURPOSE}'"]}}}' > "${PURPOSE}-ca-config.json"
  kubectl -n custom-metrics create secret tls cm-adapter-serving-certs --cert=./serving-ca.crt --key=./serving-ca.key
  

• Make changes to $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter/deploy/manifests/custom-metrics-apiserver-deployment.yaml, to point to your prometheus server and k8s-prometheus-adapter docker image.

  @@ -19,17 +19,17 @@ spec:
         serviceAccountName: custom-metrics-apiserver
         containers:
         - name: custom-metrics-apiserver
  -        image: directxman12/k8s-prometheus-adapter-amd64
  +        image: directxman12/k8s-prometheus-adapter-s390x:0.2.1
           args:
           - /adapter
           - --secure-port=6443
  -        - --tls-cert-file=/var/run/serving-cert/serving.crt
  -        - --tls-private-key-file=/var/run/serving-cert/serving.key
  +        - --tls-cert-file=/var/run/serving-cert/tls.crt
  +        - --tls-private-key-file=/var/run/serving-cert/tls.key
           - --logtostderr=true
  -        - --prometheus-url=http://prometheus.prom.svc:9090/
  +        - --prometheus-url=http://localhost:9090/
           - --metrics-relist-interval=1m
           - --v=10
  -        - --config=/default-config.yaml
  +        - --config=/etc/adapter/config.yaml
           ports:
           - containerPort: 6443
           volumeMounts:

  Notes:
  1. The --tls-private-key-file and --tls-cert-file values are obtained from the values stored in secret cm-adapter-serving-certs. Execute kubectl describe -n custom-metrics secret cm-adapter-serving-certs to view the data.
  2. The --prometheus-url is set to the server and port prometheus server has been started on.

• Deploy k8s-prometheus-adapter

  cd $GOPATH/src/github.com/directxman12/k8s-prometheus-adapter/deploy
  kubectl create -f manifests/
  

  Note: The custom metrics adapter will launch the custom-metrics-apiserver pod.

References:

• https://github.com/DirectXMan12/k8s-prometheus-adapter
• https://github.com/DirectXMan12/k8s-prometheus-adapter/tree/master/deploy
• https://github.com/DirectXMan12/k8s-prometheus-adapter/blob/master/docs/walkthrough.md