NiFi Registry behind nginx proxy with (client) SSL/TLS and basic auth

Running NiFi Registry behind nginx proxy with SSL/TLS and basic_auth (inside nginx) is a bit tricky. In this article, we will go step-by-step to create this hybrid setup:

  1. NiFi Registry listening plain HTTP on port 18080 and without authentication
  2. nginx reverse proxy listening on port 18443 with server-side SSL/TLS certificate and with optional client SSL/TLS authentication
  3. nginx reverse proxy fallback to basic auth for clients which do not present themselves with valid client SSL/TLS certificate
  4. Apache NiFi configured to use pre-baked keystore and truststore to authenticate itself using client SSL/TLS against nginx
  5. NiFi Registry Web UI browser accessible using basic auth

In this setup, NiFi does not authenticate against NiFi Registry (we will still use anonymous access), but the communication is encrypted between NiFi and nginx. By using two-way SSL between NiFi and nginx we can be sure, only NiFi with supplied private key and certificate will be able to talk our NiFi Registry. By using basic auth when no client-side SSL certificate is supplied, we can be sure, only web browsers (users) who know correct user/password are allowed to access NiFi Registry web UI.

We will prepare certificates and truststores in a way, that makes nginx sure about authenticity of NiFi client and vice-versa (using own CA, but you can buy commercial certificates if you want).

Posted by Michal Klempa on 5 April 2019
basic_auth, nginx, nifi-registry, proxy, ssl, tls

Publishing Docker image to Docker Hub using Automated builds

Although there are some resources on how to create, label and publish images to, I have found myself in need to put all those pieces together. This article is the complete example of how to create, build and test, label and publish docker image using Automated Builds with source code hosted at

In this article we will:

  • create small docker image, build it and test locally
  • create and link repository with GitHub repository
  • setup automated builds of the image
  • alter the automated builds setup to include build-time labels
  • verify the build

Posted by Michal Klempa on 8 March 2019
automation, docker, docker hub,, labels, multi-stage, sass

Using Apache NiFi to ingest SNMP tables into Avro

SNMP is a very old protocol, dating back to 1988 and was elaborated later in 90s. When it comes to hardware monitoring, however, nearly every device supports at least SNMPv2. This makes it the “good enough” choice for basic monitoring of devices.

In this article, we create a Apache NiFi data flow, which will collect SNMP tables and convert them into Avro format.

Although there is SNMP processor in NiFi available, we will proceed with different approach, since the processor does not support querying SNMP tables. Steps in this article include:

  • Preparing sandbox environment – simulator for SNMP server, setting up command line tools to grab SNMP tables (ifTable is used as an exapmle)
  • Designing the NiFi DataFlow – step-by-step data flow design instructions to query SNMP server for a table, parse the CSV-like output into Apache Avro format (one record per CSV line).

Posted by Michal Klempa on 17 October 2016
avro, iot, nifi, snmp