Month: July 2021

Mount single file in docker

We can use –mount type=bind parameter to mount single file

docker run  -d -p 9090:9090 --mount type=bind,source=/opt/prometheus/prometheus.yml,target=/etc/prometheus/prometheus.yml prom/prometheus:v2.22.0

Using docker-compose file

version: "3.7"    
services:
  prometheus:
    image: prom/prometheus:v2.22.0
    volumes:
      - type: bind
        source: /opt/prometheus/prometheus.yml
        target: /etc/prometheus/prometheus.yml
    ports:
      - 9090:9090

More : https://stackoverflow.com/questions/42248198/how-to-mount-a-single-file-in-a-volume

https://docs.docker.com/storage/bind-mounts/

raspberry pi 4 wifi setup using command line only – bash

  • find the wifi adaptor name
lshw

ls /sys/class/net

it was wlan0 in my case

  • edit /etc/netplan/50-cloud-init.yaml
network:
    ethernets:
        eth0:
            dhcp4: true
            optional: true
    version: 2
    wifis:
        wlan0:
            optional: true
            access-points:
                    "SSID-NAME":
                            password: "your_password"
            dhcp4: yes
  • Test the config
netplan try
netplan --debug try

This command will make the above changes for 120seconds if anything wrong it will be reverted back. OR you can hit Enter to make the changes.

  • apply config
netplan generate 
netplan apply
#enable wifi module

modprobe brcmfmac

#disable
modprobe -rv brcmfmac


nano /etc/modprobe.d/raspi-blacklist.conf

blacklist brcmfmac
blacklist brcmutil

More : https://raspberrypi.stackexchange.com/questions/108636/setting-wifi-up-via-the-command-line-ubuntu-server-18-04-4-lts-raspberry-pi-4

https://huobur.medium.com/how-to-setup-wifi-on-raspberry-pi-4-with-ubuntu-20-04-lts-64-bit-arm-server-ceb02303e49b

raspberry pi fan on/off automation based on cpu temp

Note : This does not work because IO pins does not enough power to run fan.

fan.py

import RPi.GPIO as GPIO
from time import sleep
import sys

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(8, GPIO.OUT, initial=GPIO.LOW) 

if sys.argv[1] == "on":
 GPIO.output(8, GPIO.HIGH)
 print("on")
else:
 GPIO.output(8, GPIO.LOW)
 print("off")

Dockerfile

FROM python:slim-buster
WORKDIR /fan
RUN apt update && \
    apt install python-rpi.gpio python3-rpi.gpio -y 
COPY fan.py .

Docker build

docker build -t fan .

Docker run command switch on

docker run -it --device /dev/gpiomem fan python2 fan.py on

Docker run command switch off

docker run -it --device /dev/gpiomem fan python2 fan.py off

fan.sh

#!/bin/bash

cpu=$(</sys/class/thermal/thermal_zone0/temp)

cpu_temp=$(echo "$cpu/1000" | /usr/bin/bc)
echo $cpu_temp

if(("cpu_temp" >= "65"))
then
echo "more 65 on fan"
docker run -it --device /dev/gpiomem fan python2 fan.py on
else
echo "less 65 off fan"
docker run -it --device /dev/gpiomem fan python2 fan.py off
fi

More: https://raspberrypihq.com/making-a-led-blink-using-the-raspberry-pi-and-python/

https://stackoverflow.com/questions/48441737/docker-error-no-access-to-dev-mem-try-running-as-root

Greylog setup with filebeat and Raw/Plaintext TCP

More : https://docs.graylog.org/en/4.0/pages/installation/docker.html

version: '2'
services:
  mongodb:
    image: mongo:4.2
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch-oss:7.10.2
    environment:
      - http.host=0.0.0.0
      - transport.host=localhost
      - network.host=0.0.0.0
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    mem_limit: 1g
  graylog:
    image: graylog/graylog:4.0
    environment:
      - GRAYLOG_PASSWORD_SECRET=somepasswordpepper
      - GRAYLOG_ROOT_PASSWORD_SHA2=8c6976e5b5410415bde908bd4dee15dfb167a9c873fc4bb8a81f6f2ab448a918
      - GRAYLOG_HTTP_EXTERNAL_URI=http://192.168.0.228:9000/
    entrypoint: /usr/bin/tini -- wait-for-it elasticsearch:9200 --  /docker-entrypoint.sh
    links:
      - mongodb:mongo
      - elasticsearch
    restart: always
    depends_on:
      - mongodb
      - elasticsearch
    ports:
      # Graylog web interface and REST API
      - 9000:9000
      # Syslog TCP
      - 1514:1514
      # Syslog UDP
      - 1514:1514/udp
      # GELF TCP
      - 12201:12201
      # GELF UDP
      - 12201:12201/udp
      - 5555:5555
      - 5551:5551

Note : 5555 port will be used for filebeat as logstash output

System / inputs >> select input > Beats > launch input > global tick > titile > port = 5555 > threads =2 > Save

  • Edit /etc/filebeat/filebeat.yml

Output:

Raw/Plaintext TCP

System / inputs >> select input > Raw/Plaintext TCP > launch input > global tick > titile > port = 5551 > threads =2 > Save

for sending Raw/Plaintext TCP

echo "this is log" > /dev/tcp/grelog_server/5551

haproxy context based routing

http://192.168.0.228:8080/app1 => http://192.168.0.228:8081
http://192.168.0.228:8080/app2 => http://192.168.0.228:8082

haproxy.cfg

global
    daemon
    maxconn 256

defaults
    timeout connect 10s
    timeout client 30s
    timeout server 30s
    mode http
    maxconn 3000

frontend http_in
    bind *:8080
    use_backend app1_backend if { path /app1 }
    use_backend app2_backend if { path /app2 }

backend app1_backend
    http-request set-path %[path,regsub(^/app1/?,/)]
    server server1 192.168.0.228:8081

backend app2_backend
    http-request set-path %[path,regsub(^/app2/?,/)]
    server server1 192.168.0.228:8082

more : https://grafana.com/tutorials/run-grafana-behind-a-proxy/#configure-haproxy

raspberry pi as kubernetes worker node

  • Install docker
apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg \
    lsb-release

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

echo \
  "deb [arch=arm64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

apt-get update

apt-get install docker-ce docker-ce-cli containerd.io

https://docs.docker.com/engine/install/ubuntu/

echo 'cgroup_memory=1' > /boot/cmdline.txt


echo '{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
' > /etc/docker/daemon.json



sudo sed -i '$ s/$/ cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1 swapaccount=1/' /boot/firmware/cmdline.txt


cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sudo sysctl --system
  • Install kubernetes component
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

apt update && sudo apt install -y kubelet kubeadm kubectl


echo '[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --cgroup-driver=systemd"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/default/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS' > /etc/systemd/system/kubelet.service.d/10-kubeadm.conf


systemctl daemon-reload

systemctl restart kubelet

https://opensource.com/article/20/6/kubernetes-raspberry-pi

https://stackoverflow.com/questions/45708175/kubelet-failed-with-kubelet-cgroup-driver-cgroupfs-is-different-from-docker-c