Linux and DevOps with Vijay

I purchased a Thinkpad for use of fedora as my preferred  workstation OS. After installation feel few issues in wireless network.e.g. My macbook reports speedtest 99~110 Mbps  - ( folks i have 100Mbps connection )  Wherein my fedora reports only 24~30 Mbps While i am transfering any file in my lab systems over wifi macbook speed again fast but fedora remains same 20~ 30 Mbps ( yes in wifi LAN even ) So i found the issue after few search and i thought to lets share  this with you too. Here is fix. $ vim /etc/modprobe.d/iwl11n.conf edit bellow lines as options iwlwifi 11n_disable=8 options iwlwifi nohwcrypt=8 In above actually  old value was options iwlwifi 11n_disable=1 save and exit have a reboot enjoy !

Install packages for network and dns $ apt install ifupdown resolvconf -y remove cloud-init $ apt remove cloud-init -y delete netplan config $ rm -rf /etc/netplan/* $ reboot $ vim /etc/network/interfaces auto lo iface lo inet loopback auto ens3 iface ens3 inet static address 192.168.1.154 netmask 255.255.252.0 gateway 192.168.1.1 dns-nameservers  192.168.1.30 $ vim /etc/resolvconf/resolv.conf.d/head nameserver 8.8.8.8 nameserver 8.8.4.4 save and reboot now check dns entries $ cat /etc/resolv.conf

Configure alert manager to send mail. This will send mail to 2 diffrent groups one is managemnet group for ciritical alerts only and second is default group for all alerts. $  oc project openshift-monitoring The secret file where alertmanager.yaml content ( encoded in base64 ) will remain is alertmanager-main convert the yaml content into base64 first $  cat alertmanager.yaml | base64 -w0 copy value now edit secret $ oc edit secret alertmanager-main find value starts with alertmanager.yaml: replace all base64 content from your own . save and exit now in order to take this secret in effect we must bounce the pod $  oc delete po -l alertmanager=main check if all pod came online $  oc get po -l alertmanager=main done! alertmanager.yaml content resolve_timeout : 5m route : group_wait : 30s group_interval : 5m repeat_interval : 12h ...

Install required packages for source code nginx build # apt-get install -y build-essential ca-certificates wget curl libpcre3 libpcre3-dev autoconf unzip automake libtool tar git libssl-dev zlib1g-dev uuid-dev lsb-release vim htop sysstat ufw fail2ban makepasswd libgd-dev libgeoip-dev -y create a directory # mkdir /usr/local/src/nginx/ # cd /usr/local/src/nginx/ download and extract nginx tar # wget -qO- http://nginx.org/download/nginx-1.14.2.tar.gz | tar zxf - clone nginx rtmp module # git clone https://github.com/arut/nginx-rtmp-module Download other modules - PCRE version 8.42 # wget https://ftp.pcre.org/pub/pcre/pcre-8.42.tar.gz && tar xzvf pcre-8.42.tar.gz - zlib version 1.2.11 # wget https://www.zlib.net/zlib-1.2.11.tar.gz && tar xzvf zlib-1.2.11.tar.gz - OpenSSL version 1.1.0h # wget https://www.openssl.org/source/openssl-1.1.0h.tar.gz && tar xzvf openssl-1.1.0h.tar.gz # cd nginx-1.14.2/ configure  nginx with modules and options # ./configure --add-...

~~~~~ Setup pcs cluster lab on kvm libvirt ~~~~~~~~~ ---------------------------------------------------- host - kvm.mylab.local guest- hanode1.mylab.local    | 192.168.122.83 guest- hanode2.mylab.local    | 192.168.122.84 ~~~~~~~~~~~~~On KVM Host~~~~~~~~~~~~~ yum install fence-virt fence-virtd fence-virtd-libvirt fence-virtd-multicast fence-virtd-serial  mkdir /etc/cluster  dd if=/dev/urandom of=/etc/cluster/fence_xvm.key bs=4k count=1  -- hit enter for all in above  firewall-cmd --permanent --add-service=fence_virt  firewall-cmd --permanent --add-port=1229/udp  firewall-cmd --permanent --add-port=1229/tcp  firewall-cmd --reload  systemctl start fence_virtd.service  systemctl enable fence_virtd.service  systemctl status fence_virtd.service   fence_virtd -c  ssh [email protected] mkdir /etc/cluster  ssh [email protected] mkdir /etc/cluster  scp /etc/cluster/fence_xvm.key [email protected]....

Bellow is the process for setting up GO Language in centos 7 or ubuntu 18.04 Download package $ wget https://dl.google.com/go/go1.14.linux-amd64.tar.gz extract binary $ tar -C /usr/local -xzf go1.14.linux-amd64.tar.gz setup path $ export PATH=$PATH:/usr/local/go/bin set permanent path in user profile $ vim ~/.bash_profile create environment directory $ mkdir ~/go create a test programm $ mkdir ~/go/src/hello -p $ cd go/src/hello/ $ vim hello.go -- package main import "fmt" func main() {     fmt.Printf("Hello, World\n") } -- $ go build  $ ./hello

Setup Prometheus with grafana for linux monitoring Update system to latest $ yum update -y Disable Selinux Open SELinux configuration and edit the file: vim /etc/sysconfig/selinux Change “SELINUX=enforcing” to “SELINUX=disabled”. Save and exit the file. Then reboot the system. reboot Download package from https://prometheus.io/download/ Run the following command to download package. Paste the copied URL after wget in the below command: wget https://github.com/prometheus/prometheus/releases/download/v2.16.0/prometheus-2.16.0.linux-amd64.tar.gz Step 4 – Configure Prometheus Add a Prometheus user. useradd --no-create-home --shell /bin/false prometheus Create needed directories. mkdir /etc/prometheus mkdir /var/lib/prometheus Change the owner of the above directories. chown prometheus:prometheus /etc/prometheus chown prometheus:prometheus /var/lib/prometheus Now go to Prometheus downloaded location and extract it. tar -xvzf prometheus-2.8.1.linux-...