U1.45 Ubuntu Quick Start (QS): Network Configuration. Virtual IP. Load Balancer. - chempkovsky/CS2WPF-and-CS2XAMARIN GitHub Wiki

Reading

netplan file name

  • to get netplan file name run the command:
yury@u2004s01:~$ sudo ls -l /etc/netplan
total 4
-rw-r--r-- 1 root root 115 Dec 16 11:14 00-installer-config.yaml

Modify 00-installer-config.yaml

  • the content of the file should be as shown below
    • 192.168.100.11 is a primary IP
    • 192.168.100.9 is a secondary IP (or virtual IP)
    • secondary IP can be assigned to more than one host
network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: no
      addresses:
        - 192.168.100.11/24
        - 192.168.100.9/24
      gateway4: 192.168.100.1
      nameservers:
          search: [mydomain, otherdomain]
          addresses: [8.8.8.8, 4.4.4.4]

Apply modification

  • run the command
sudo netplan apply

Load balancer with haproxy keepalived

We start with

  • Pre-installed DHCP in the virtual environment (for example, a hardware implementation of a DHCP server in a modem)
  • Go to the page Ubuntu 20.04.3 LTS (Focal Fossa)
  • Download ubuntu-20.04.3-live-server-amd64.iso
  • Deploy two virtual machines with default settings (i.e. openssh is ON)
    • u2004s04 192.168.100.44
    • u2004s05 192.168.100.45
  • Sudo-enabled User
    • yury

Virtual IP

  • 192.168.100.50

Port

  • 6443

Suppose

  • we have two Kubernetes Control Plane hosts with default API server port
    • u2004s01 192.168.100.41:6443
    • u2004s02 192.168.100.42:6443

Install haproxy keepalived binary for u2004s04 u2004s05

  • for u2004s04 u2004s05
sudo apt-get update
sudo apt-get install -y haproxy keepalived

Configure u2004s04

  • for u2004s04
sudo nano /etc/keepalived/keepalived.conf
click to show the content of /etc/keepalived/keepalived.conf 
global_defs {
    router_id LVS_DEVEL
}
vrrp_script check_apiserver {
  script "/etc/keepalived/check_apiserver.sh"
  interval 3
  weight -2
  fall 10
  rise 2
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 101
    authentication {
        auth_type PASS
        auth_pass 42
    }
    virtual_ipaddress {
        192.168.100.50
    }
    track_script {
        check_apiserver
    }
}
  • for u2004s04
sudo nano /etc/keepalived/check_apiserver.sh
click to show the content of /etc/keepalived/check_apiserver.sh 
errorExit() {
    echo "*** $*" 1>&2
    exit 1
}

curl --silent --max-time 2 --insecure https://localhost:6443/ -o /dev/null || errorExit "Error GET https://localhost:6443/"
if ip addr | grep -q 192.168.100.50; then
    curl --silent --max-time 2 --insecure https://192.168.100.50:6443/ -o /dev/null || errorExit "Error GET https://192.168.100.50:6443/"
fi
  • for u2004s04
sudo nano /etc/haproxy/haproxy.cfg
click to show the content of /etc/keepalived/check_apiserver.sh 
global
    log /dev/log local0
    log /dev/log local1 notice
    daemon

defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 1
    timeout http-request    10s
    timeout queue           20s
    timeout connect         5s
    timeout client          20s
    timeout server          20s
    timeout http-keep-alive 10s
    timeout check           10s


frontend apiserver
    bind *:6443
    mode tcp
    option tcplog
    default_backend apiserver

backend apiserver
    option httpchk GET /healthz
    http-check expect status 200
    mode tcp
    option ssl-hello-chk
    balance     roundrobin
    server u2004s01 192.168.100.41:6443 check
    server u2004s02 192.168.100.42:6443 check
  • for u2004s04
sudo systemctl enable haproxy --now
sudo systemctl enable keepalived --now
  • ip a returns additional IP= 192.168.100.50/32
click to show the response 
yury@u2004s04:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:64:03:35 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.44/24 brd 192.168.100.255 scope global dynamic eth0
       valid_lft 255684sec preferred_lft 255684sec
    inet 192.168.100.50/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::215:5dff:fe64:335/64 scope link
       valid_lft forever preferred_lft forever

Configure u2004s05

  • for u2004s05
sudo nano /etc/keepalived/keepalived.conf
click to show the content of /etc/keepalived/keepalived.conf 
global_defs {
    router_id LVS_DEVEL
}
vrrp_script check_apiserver {
  script "/etc/keepalived/check_apiserver.sh"
  interval 3
  weight -2
  fall 10
  rise 2
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 100
    authentication {
        auth_type PASS
        auth_pass 42
    }
    virtual_ipaddress {
        192.168.100.50
    }
    track_script {
        check_apiserver
    }
}
  • for u2004s05
sudo nano /etc/keepalived/check_apiserver.sh
click to show the content of /etc/keepalived/check_apiserver.sh 
errorExit() {
    echo "*** $*" 1>&2
    exit 1
}

curl --silent --max-time 2 --insecure https://localhost:6443/ -o /dev/null || errorExit "Error GET https://localhost:6443/"
if ip addr | grep -q 192.168.100.50; then
    curl --silent --max-time 2 --insecure https://192.168.100.50:6443/ -o /dev/null || errorExit "Error GET https://192.168.100.50:6443/"
fi
  • for u2004s05
sudo nano /etc/haproxy/haproxy.cfg
click to show the content of /etc/keepalived/check_apiserver.sh 
global
    log /dev/log local0
    log /dev/log local1 notice
    daemon

defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 1
    timeout http-request    10s
    timeout queue           20s
    timeout connect         5s
    timeout client          20s
    timeout server          20s
    timeout http-keep-alive 10s
    timeout check           10s


frontend apiserver
    bind *:6443
    mode tcp
    option tcplog
    default_backend apiserver

backend apiserver
    option httpchk GET /healthz
    http-check expect status 200
    mode tcp
    option ssl-hello-chk
    balance     roundrobin
    server u2004s01 192.168.100.41:6443 check
    server u2004s02 192.168.100.42:6443 check
  • for u2004s05
sudo systemctl enable haproxy --now
sudo systemctl enable keepalived --now
  • ip a does not return additional IP=192.168.100.50/32
click to show the response 
yury@u2004s05:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:64:03:36 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.45/24 brd 192.168.100.255 scope global dynamic eth0
       valid_lft 255430sec preferred_lft 255430sec
    inet6 fe80::215:5dff:fe64:336/64 scope link
       valid_lft forever preferred_lft forever

Simple test

  • after turning off u2004s04
    • for u2004s05: ip a does return additional IP=192.168.100.50/32
click to show the response 
yury@u2004s05:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:64:03:36 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.45/24 brd 192.168.100.255 scope global dynamic eth0
       valid_lft 255269sec preferred_lft 255269sec
    inet 192.168.100.50/32 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::215:5dff:fe64:336/64 scope link
       valid_lft forever preferred_lft forever
  • after restart ** u2004s04 **
    • for u2004s05: ip a does not return additional IP=192.168.100.50/32
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