If you try to setup Kubernetes cluster on bare metal system, you will notice that Load-Balancer always remain in the “pending” state indefinitely when created. This is expected because Kubernetes, by default does not offer an implementation of network load-balancer for bare metal cluster.
In a cloud-enabled Kubernetes cluster, you request a load-balancer, and your cloud platform assigns an IP address to you. In a bare metal cluster, you need an external Load-Balancer implementation which has capability to perform an IP allocation.
Enter MetalLB…
MetalLB is a load-balancer implementation for bare metal Kubernetes clusters, using standard routing protocols. MetalLB provides a network load-balancer implementation for Kubernetes clusters that do not run on a supported cloud provider, effectively allowing the usage of LoadBalancer Services within any cluster. It aims to redress this imbalance by offering a Network LB implementation that integrates with standard network equipment, so that external services on bare metal clusters also “just work” as much as possible.
Why can’t Ingress help me out here?
Yes, Ingress could be one of the best option if you deployed Kubernetes cluster on bare metal. Ingress lets you configure internal load balancing of HTTP or HTTPS traffic to your deployed services using software load balancers like NGINX or HAProxy deployed as pods in your cluster. Ingress makes use of Layer 7 routing of your applications as well. The problem with this is that it doesn’t easily route TCP or UDP traffic. The best way to do this was using a LoadBalancer type of service. However, if you deployed your Kubernetes cluster to bare metal you didn’t have the option of using a LoadBalancer.
How does MetalLB work?
MetalLB hooks into your Kubernetes cluster, and provides a network load-balancer implementation. In short, it allows you to create Kubernetes services of type “LoadBalancer” in clusters that don’t run on a cloud provider, and thus cannot simply hook into paid products to provide load-balancers.
It is important to note that MetalLB cannot create IP addresses out of thin air, so you do have to give it pools of IP addresses that it can use. It will then take care of assigning and unassigning individual addresses as services come and go, but it will only ever hand out IPs that are part of its configured pools.
Okay wait.. How will I get IP Address pool for MetalLB?
How you get IP address pools for MetalLB depends on your environment. If you’re running a bare metal cluster in a colocation facility, your hosting provider probably offers IP addresses for lease. In that case, you would lease, say, a /26 of IP space (64 addresses), and provide that range to MetalLB for cluster services.
Under this blog post, I will showcase how to setup 3-Node Kubernetes cluster using MetalLB. The below steps have also been tested for ESXi Virtual Machines and works flawlessly.
Preparing the Infrastructure
- Machine #1(Master): 10.94.214.206
- Machine #2(Worker Node1): 10.94.214.210
- Machine #3(Worker Node2): 10.94.214.213
Assign hostname to each of these systems:
~$ cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 ubuntu1804-1
10.94.214.206 kubemaster.dell.com
10.94.214.210 node1.dell.com
10.94.214.213 node2.dell.com
Installing curl package
$ sudo apt install curl
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
libcurl4
The following NEW packages will be installed:
curl libcurl4
0 upgraded, 2 newly installed, 0 to remove and 472 not upgraded.
Need to get 373 kB of archives.
After this operation, 1,036 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 libcurl4 amd64 7.58.0-2ubuntu3.7 [214 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 curl amd64 7.58.0-2ubuntu3.7 [159 kB]
Fetched 373 kB in 2s (164 kB/s)
Selecting previously unselected package libcurl4:amd64.
(Reading database ... 128791 files and directories currently installed.)
Preparing to unpack .../libcurl4_7.58.0-2ubuntu3.7_amd64.deb ...
Unpacking libcurl4:amd64 (7.58.0-2ubuntu3.7) ...
Selecting previously unselected package curl.
Preparing to unpack .../curl_7.58.0-2ubuntu3.7_amd64.deb ...
Unpacking curl (7.58.0-2ubuntu3.7) ...
Setting up libcurl4:amd64 (7.58.0-2ubuntu3.7) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Processing triggers for man-db (2.8.3-2) ...
Setting up curl (7.58.0-2ubuntu3.7) ...
Installing Docker
$ sudo curl -sSL https://get.docker.com/ | sh
# Executing docker install script, commit: 2f4ae48
+ sudo -E sh -c apt-get update -qq >/dev/null
+ sudo -E sh -c apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
+ sudo -E sh -c curl -fsSL "https://download.docker.com/linux/ubuntu/gpg" | apt-key add -qq - >/dev/null
Warning: apt-key output should not be parsed (stdout is not a terminal)
+ sudo -E sh -c echo "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable" > /etc/apt/sources.list.d/docker.list
+ sudo -E sh -c apt-get update -qq >/dev/null
+ [ -n ]
+ sudo -E sh -c apt-get install -y -qq --no-install-recommends docker-ce >/dev/null
+ sudo -E sh -c docker version
Client:
Version: 18.09.7
API version: 1.39
Go version: go1.10.8
Git commit: 2d0083d
Built: Thu Jun 27 17:56:23 2019
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 18.09.7
API version: 1.39 (minimum version 1.12)
Go version: go1.10.8
Git commit: 2d0083d
Built: Thu Jun 27 17:23:02 2019
OS/Arch: linux/amd64
Experimental: false
If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:
sudo usermod -aG docker cse
Remember that you will have to log out and back in for this to take effect!
WARNING: Adding a user to the "docker" group will grant the ability to run
containers which can be used to obtain root privileges on the
docker host.
Refer to https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface
for more information.
cse@kubemaster:~$
~$ sudo docker version
Client:
Version: 18.09.7
API version: 1.39
Go version: go1.10.8
Git commit: 2d0083d
Built: Thu Jun 27 17:56:23 2019
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 18.09.7
API version: 1.39 (minimum version 1.12)
Go version: go1.10.8
Git commit: 2d0083d
Built: Thu Jun 27 17:23:02 2019
OS/Arch: linux/amd64
Experimental: false
Add the Kubernetes signing key on both the nodes
$ sudo curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add
OK
Adding Xenial Kubernetes Repository on both the nodes
sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"
Installing Kubeadm
sudo apt install kubeadm
Verifying Kubeadm installation
$ sudo kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.0", GitCommit:"e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529", GitTreeState:"clean", BuildDate:"2019-06-19T16:37:41Z", GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"}
Disable swap memory (if running) on both the nodes
sudo swapoff -a
Script to setup K8s Cluster
kubeadm init --apiserver-advertise-address $(hostname -i)
mkdir -p $HOME/.kube
chown $(id -u):$(id -g) $HOME/.kube/config
kubectl apply -n kube-system -f \
"https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 |tr -d '\n')"
Adding Worker Node
cse@ubuntu1804-1:~$ sudo swapoff -a
cse@ubuntu1804-1:~$ sudo kubeadm join 10.94.214.210:6443 --token aju7kd.5mlhmmo1wlf8d5un --discovery-token-ca-cert-hash sha256:89541bb9bbe5ee1efafe17b20eab77e6b756bd4ae023d2ff7c67ce73e3e8c7bb
cse@ubuntu1804-1:~$ sudo swapoff -a
cse@ubuntu1804-1:~$ sudo kubeadm join 10.94.214.210:6443 --token aju7kd.5mlhmmo1wlf8d5un --discovery-token-ca-cert-hash sha256:89541bb9bbe5ee1efafe17b20eab77e6b756bd4ae023d2ff7c67ce73e3e8c7bb
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.15" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Activating the kubelet service
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.
Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
cse@ubuntu1804-1:~$Listing the Nodes
cse@kubemaster:~$ sudo kubectl get nodes
NAME STATUS ROLES AGE VERSION
kubemaster Ready master 8m17s v1.15.0
worker1.dell.com Ready <none> 5m22s v1.15.0
cse@kubemaster:~$
cse@kubemaster:~$ sudo kubectl describe node worker1.dell.com
Name: worker1.dell.com
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=worker1.dell.com
kubernetes.io/os=linux
Annotations: kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
node.alpha.kubernetes.io/ttl: 0
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Fri, 05 Jul 2019 16:10:33 -0400
Taints: <none>
Unschedulable: false
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Fri, 05 Jul 2019 16:10:55 -0400 Fri, 05 Jul 2019 16:10:55 -0400 WeaveIsUp Weave pod has set this
MemoryPressure False Fri, 05 Jul 2019 16:15:33 -0400 Fri, 05 Jul 2019 16:10:33 -0400 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Fri, 05 Jul 2019 16:15:33 -0400 Fri, 05 Jul 2019 16:10:33 -0400 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Fri, 05 Jul 2019 16:15:33 -0400 Fri, 05 Jul 2019 16:10:33 -0400 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Fri, 05 Jul 2019 16:15:33 -0400 Fri, 05 Jul 2019 16:11:03 -0400 KubeletReady kubelet is posting ready status. AppArmor enabled
Addresses:
InternalIP: 10.94.214.213
Hostname: worker1.dell.com
Capacity:
cpu: 2
ephemeral-storage: 102685624Ki
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 4040016Ki
pods: 110
Allocatable:
cpu: 2
ephemeral-storage: 94635070922
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 3937616Ki
pods: 110
System Info:
Machine ID: e7573bb6bf1e4cf5b9249413950f0a3d
System UUID: 2FD93F42-FA94-0C27-83A3-A1F9276469CF
Boot ID: 782d6cfc-08a2-4586-82b6-7149389b1f4f
Kernel Version: 4.15.0-29-generic
OS Image: Ubuntu 18.04.1 LTS
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://18.9.7
Kubelet Version: v1.15.0
Kube-Proxy Version: v1.15.0
Non-terminated Pods: (4 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
default my-nginx-68459bd9bb-55wk7 0 (0%) 0 (0%) 0 (0%) 0 (0%) 4m8s
default my-nginx-68459bd9bb-z5r45 0 (0%) 0 (0%) 0 (0%) 0 (0%) 4m8s
kube-system kube-proxy-jt4bs 0 (0%) 0 (0%) 0 (0%) 0 (0%) 5m51s
kube-system weave-net-kw9gg 20m (1%) 0 (0%) 0 (0%) 0 (0%) 5m51s
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 20m (1%) 0 (0%)
memory 0 (0%) 0 (0%)
ephemeral-storage 0 (0%) 0 (0%)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 5m51s kubelet, worker1.dell.com Starting kubelet.
Normal NodeHasSufficientMemory 5m51s (x2 over 5m51s) kubelet, worker1.dell.com Node worker1.dell.com status is now: NodeHasSufficientMemory
Normal NodeHasNoDiskPressure 5m51s (x2 over 5m51s) kubelet, worker1.dell.com Node worker1.dell.com status is now: NodeHasNoDiskPressure
Normal NodeHasSufficientPID 5m51s (x2 over 5m51s) kubelet, worker1.dell.com Node worker1.dell.com status is now: NodeHasSufficientPID
Normal NodeAllocatableEnforced 5m51s kubelet, worker1.dell.com Updated Node Allocatable limit across pods
Normal Starting 5m48s kube-proxy, worker1.dell.com Starting kube-proxy.
Normal NodeReady 5m21s kubelet, worker1.dell.com Node worker1.dell.com status is now: NodeReady
cse@kubemaster:~$
$ sudo kubectl run nginx --image nginx
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/nginx created
~$
Configuring Metal LoadBalancer
kubectl apply -f https://raw.githubusercontent.com/google/metallb/v0.7.3/manifests/metallb.yaml
~$ sudo kubectl get ns
NAME STATUS AGE
default Active 23h
kube-node-lease Active 23h
kube-public Active 23h
kube-system Active 23h
metallb-system Active 13m
$ kubectl get all -n metallb-system
NAME READY STATUS RESTARTS AGE
pod/controller-547d466688-m9xlt 1/1 Running 0 13m
pod/speaker-tb9d7 1/1 Running 0 13m
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE
daemonset.apps/speaker 1 1 1 1 1 <none> 13m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/controller 1/1 1 1 13m
NAME DESIRED CURRENT READY AGE
replicaset.apps/controller-547d466688 1 1 1 13m
There are 2 components :
- Controller – Assigns the IP address to the LB
- Speaker – Ensure that you can reach service through LB
Controller component is deployed as deplyment and speaker as daemonset which is running on all worker nodes
Next, we need to look at config files.
To configure MetalLB, write a config map to metallb-system/config
Link: https://metallb.universe.tf/configuration/
Layer 2 mode is the simplest to configure: in many cases, you don’t need any protocol-specific configuration, only IP addresses.
sudo kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
kubemaster Ready master 23h v1.15.0 10.94.214.210 <none> Ubuntu 18.04.1 LTS 4.15.0-29-generic docker://18.9.7
worker1.dell.com Ready <none> 23h v1.15.0 10.94.214.213 <none> Ubuntu 18.04.1 LTS 4.15.0-29-generic docker://18.9.7
We need to pay attention to the above Internal IP. We need to use this range only.
$ sudo cat <<EOF | kubectl create -f -
> apiVersion: v1
> kind: ConfigMap
> metadata:
> namespace: metallb-system
> name: config
> data:
> config: |
> address-pools:
> - name: default
> protocol: layer2
> addresses:
> - 10.94.214.200-10.94.214.255
>
> EOF
configmap/config created
cse@kubemaster:~$ kubectl describe configmap config -n metallb-system
Name: config
Namespace: metallb-system
Labels: <none>
Annotations: <none>
Data
====
config:
----
address-pools:
- name: default
protocol: layer2
addresses:
- 10.94.26.214-10.94.214.255
Events: <none>
kubectl get all
$ kubectl expose deploy nginx --port 80 --type LoadBalancer
service/nginx exposed
Every 2.0s: kubectl get all kubemaster: Sat Jul 6 15:33:30 2019
NAME READY STATUS RESTARTS AGE
pod/nginx-7bb7cd8db5-rc8c4 1/1 Running 0 18m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S)
AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP
23h
service/nginx LoadBalancer 10.105.157.210 10.94.214.200 80:3063
1/TCP 34s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 1/1 1 1 18m
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-7bb7cd8db5 1 1 1 18m
By now, you should be able to browser NGINX Page underhttp://10.94.214.210
Hurray !!!
Let’s run another nginx service:
~$ kubectl run nginx2 --image nginx
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/nginx2 created
Every 2.0s: kubectl get all kubemaster: Sat Jul 6 15:37:21 2019
NAME READY STATUS RESTARTS AGE
pod/nginx-7bb7cd8db5-rc8c4 1/1 Running 0 21m
pod/nginx2-5746fc444c-4tsls 1/1 Running 0 42s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S)
AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP
23h
service/nginx LoadBalancer 10.105.157.210 10.94.214.200 80:3063
1/TCP 4m24s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 1/1 1 1 21m
deployment.apps/nginx2 1/1 1 1 42s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-7bb7cd8db5 1 1 1 21m
replicaset.apps/nginx2-5746fc444c 1 1 1 42s
cse@kubemaster:~$ kubectl expose deploy nginx2 --port 80 --type LoadBalancer
service/nginx2 exposed
cse@kubemaster:~$
Every 2.0s: kubectl get all kubemaster: Sat Jul 6 15:38:49 2019
NAME READY STATUS RESTARTS AGE
pod/nginx-7bb7cd8db5-rc8c4 1/1 Running 0 23m
pod/nginx2-5746fc444c-4tsls 1/1 Running 0 2m10s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S)
AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP
23h
service/nginx LoadBalancer 10.105.157.210 10.94.214.200 80:3063
1/TCP 5m52s
service/nginx2 LoadBalancer 10.107.32.195 10.94.214.201 80:3139
0/TCP 15s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 1/1 1 1 23m
deployment.apps/nginx2 1/1 1 1 2m10s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nginx-7bb7cd8db5 1 1 1 23m
replicaset.apps/nginx2-5746fc444c 1 1 1 2m10s
Let’s run hellowhale example
cse@kubemaster:~$ sudo kubectl run hellowhale --image ajeetraina/hellowhale
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/hellowhale created
cse@kubemaster:~$
cse@kubemaster:~$ sudo kubectl expose deploy hellowhale --port 89 --type LoadBalancer
service/hellowhale exposed
cse@kubemaster:~$
cse@kubemaster:~$ sudo kubectl get all
NAME READY STATUS RESTARTS AGE
pod/hellowhale-64ff675cb5-c95qf 1/1 Running 0 99s
pod/nginx-7bb7cd8db5-rc8c4 1/1 Running 0 2d9h
pod/nginx2-5746fc444c-4tsls 1/1 Running 0 2d8h
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/hellowhale LoadBalancer 10.100.239.246 10.94.214.203 89:30385/TCP 29s
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3d8h
service/nginx LoadBalancer 10.105.157.210 10.94.214.200 80:30631/TCP 2d8h
service/nginx2 LoadBalancer 10.107.32.195 10.94.24.201 80:31390/TCP 2d8h
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hellowhale 1/1 1 1 99s
deployment.apps/nginx 1/1 1 1 2d9h
deployment.apps/nginx2 1/1 1 1 2d8h
NAME DESIRED CURRENT READY AGE
replicaset.apps/hellowhale-64ff675cb5 1 1 1 99s
replicaset.apps/nginx-7bb7cd8db5 1 1 1 2d9h
replicaset.apps/nginx2-5746fc444c 1 1 1 2d8hHence, you saw that it’s so easy to deploy Kubernetes on bare metal using various popular operating systems like Ubuntu Linux, CentOS, SLES or Red Hat Enterprise Linux. Bare Metal Kubernetes deployments are no longer second-class deployments. Now, you, too, can use LoadBalancer resources with Kubernetes Metallb.
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