yet another developer’s blog
Prometheus has certainly become the most used solution to monitor applications running in a distributed system such as Kubernetes.
It quite simple to expose metrics in a Spring Boot application that can be scraped using Prometheus.
Continue reading “Monitor Spring Boot Metrics using Prometheus and Grafana”One of the notable Spring Boot 2 features is the introduction of Micrometer (SLF4J for application metrics).
Spring Boot ships with a whole series of built-in metrics collecting JVM metrics (memory usage, garbage collection, threads, and classes), CPU usage, Tomcat metrics as well as others.
Continue reading “Send Spring Boot Metrics into InfluxDB and Grafana”
The combination of InfluxDB, Telegraf and Grafana lets you collect and visualise almost any data. Here is who is doing what:
The result of this tutorial will be a nice dashboard of the system usage on a Raspberry PI.
Continue reading “InfluxDB, Telegraf and Grafana on a Raspberry PI”
Fixing a disk space problem on a Linux server without a graphical interface is tedious without the right command line tools handy.
A quick df -h lists all disks and their current usage.
To find large folders with files to clean up, you can use ncdu. Install it (sudo apt-get install ncdu ) and start it pointing to a certain folder.
ncdu /var/lib/jenkins/
At avisec we decided to use Kotlin when we started to rewrite our backend service. This has proven to be a very good decision. Here are my top 10 reasons why I do love Kotlin:
Let’s hope the current adoption rate of Kotlin continues and it will become a widely used alternative for Java on the JVM.
Assuming you are working somewhere with a small team and you need a local Windows share to collaborate on documents and oder data. A first choice would obviously be to use Dropbox or a similar cloud service. However if you do not want to send your data to another company or if your internet connection is unstable, you might want to use a server in your local network. My suggestion here is the following: Grab yourself a Rapberry PI, configure a Windows compatible Samba share and start using it.
It is as easy as this:
sudo tcpdump -s 0 -i eth0 -w network-traffic.pcap
The resulting file can be analyzed using Wireshark.
We’ve been facing recurring TLS issues with Mosquitto, our MQTT broker. The clients tried to send a message and lost the connection in a random and non-reproducible manner. In the Mosquitto error log we always found the following problem:
May 8 13:40:12 ip-172-31-37-49 mosquitto[29510]: OpenSSL Error: error:140F3042:SSL routines:SSL_UNDEFINED_CONST_FUNCTION:called a function you should not call
This issue is reported on GitHub and there seems to be no solution to it yet. However wiebeytec recommended to use an NGINX stream proxy to terminate the TLS connection and forward the decrypted traffic locally to Mosquitto. This is what we did and it solved our issue too!
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
stream {
server {
listen 8883 ssl;
proxy_pass mosquitto_backend;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers AES128-SHA:AES256-SHA:RC4-SHA:DES-CBC3-SHA:RC4-MD5;
ssl_certificate /opt/mqtt/broker.crt;
ssl_certificate_key /opt/mqtt/broker.key;
ssl_client_certificate /opt/mqtt/ca.crt;
ssl_verify_client on;
ssl_session_cache shared:SSL:10m;
ssl_session_timeout 10m;
}
upstream mosquitto_backend {
server 127.0.0.1:1883;
}
}
Here we go, Yellow Lite is ready. Don’t you want to give it a test drive?
https://foto-webcam.shop/en/yellow-lite/
To launch a Jenkins server in a Docker container using Docker Compose, the following docker-compose.yml defines a Jenkins server with a persistent job configuration.
jenkins:
image: "jenkins:alpine"
ports:
- 8080:8080
volumes:
- /var/jenkins_home
And start then start it:
docker-compose up
You should now have a Jenkins running on localhost:8080.
If you need a bash to change any configuration, start it like this:
docker exec -i -t jenkins_jenkins_1 /bin/bash