Tag Archives: Networks

Kubernetes: ClusterIP vs NodePort vs LoadBalancer, Services, and Ingress – an overview with examples

24 June 2020
 

 For network communications, Kubernetes presents four Service types – ClusterIP (the default one), NodePort, LoadBalancer, and ExternalName, plus the Ingress resources. In this post, we will take a short overview of all of them, and will check how they are working. The documentation is available here – Publishing Services (ServiceTypes). I’m using AWS Elastic Kubernetes… Read More »

Kubernetes: 503 no endpoints available for service – causes and solutions

15 June 2020
 

 We have a Redis service running behind a Service with the ClusterIP type. This Redis must accessible by pods from the same namespace (a Gorush service). The problem is that those pod can’t connect to the Redis service using its gorush-server-redis-svc:6379 name and reporting “Can’t connect redis server: connection refused“: Although the service is present… Read More »

Redis: “psync scheduled to be closed ASAP for overcoming of output buffer limits” and the client-output-buffer-limit

26 February 2020
 

 We have a Redis-cluster with Master-slave replication and Sentinel, see the Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel, Redis: fork – Cannot allocate memory, Linux, virtual memory and vm.overcommit_memory, and Redis: main configuration parameters and performance tuning overview posts. The system worked great until we started using it much more actively. Redis… Read More »

HTTP: redirects, POST and GET requests, and the “lost” data

23 November 2019
 

 We have a web application which has to accept POST-requests from clients. In front of this application, there is some proxy service, no matter which – initially, we faced the issues on an AWS’s Application Load Balancer, then I reproduced them with NGINX, and it will “work” for any other proxying system. Besides proxying –… Read More »

dnsmasq: AWS – “Temporary failure in name resolution”, logs, debug and dnsmasq cache size

28 October 2019
 

 We are using AWS VPC DNS and sometimes facing with errors like “php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution“. The only advice from AWS tech. support was to configure a local dnsmasq service to act as a local DNS cache, but I did this already year ago and this issue happens once in 1-2-3… Read More »

OpenVPN: the No route to host and ERR_ADDRESS_UNREACHABLE errors – the cause and a solution

14 October 2019
 

 We have an OpenVPN Access Server running, see its setup in the OpenVPN: OpenVPN Access Server set up and AWS VPC peering configuration post. The VPN server is hosted in a first AWS VPC, while a Bitwarden service – in another one VPC. Between those VPCs we have a VPC peering configured, and the OpenVPN… Read More »

Redis: main configuration parameters and performance tuning overview

10 September 2019
 

 Currently configuring Redis server as our backend caching service and during that wrote this post with some things to pay attention at in Redis config file. Shortly enough but with links to other posts or documentation. Let’s begin with the redis-benchmark utility. Will be installed alongside with Redis service, so can be used right after… Read More »

Docker: Compose shared networks

20 August 2019
 

 We have a Docker Compose stack with Jenkins, SonarQube, and PostgresSQL, check the SonarQube: running tests from Jenkins Pipeline in Docker post. The problem is that they are described in the same Docker Compose file and are restarted by the same systemd file (check the Linux: systemd сервис для Docker Compose post, Rus) Thus, if… Read More »

Kubernetes: part 3 – AWS EKS overview and manual EKS cluster set up

15 August 2019
 

 Let’s proceed with our Kubernetes journey. Previous parts: Kubernetes: part 1 – architecture and main components overview Kubernetes: part 2 – a cluster set up on AWS with AWS cloud-provider and AWS LoadBalancer In this part we will start working with AWS Elastic Kuberneters Service (EKS) – its short overview, then will create Kubernetes Control… Read More »

Redis: Sentinel – bind 0.0.0.0, the localhost issue and the announce-ip option

10 April 2019
 

 Originally, in a Sentinel’s configs, I have used the bind 0.0.0.0 to make them accessible from external hosts. Because of this when I started rolling out this setup on a real environment faced with an issue when Sentinels could not determine a Master host and other Sentinel hosts. In this post – such an issue… Read More »