One of the useful and powerful function is the roll back for me. Basically, all applications on our cluster are deployed automatically by CodePipeline in AWS but if some trouble happen, rolling back to the previous version is one of our options. At that time, all I have to do is the following command. 1$ kubectl …

When running Memcached on the Kubernetes cluster, the cache data will disappear whenever the pod restarts. I know that Redis has the built-in replication and it can be able to have data on persistence disks. However, I have some reasons to run the Memecached on our Kubernetes cluster. So, I was thinking about it and I …

Once build the CI/CD which runs automatically from build to deployment, developers are afraid that some problematic container image will be deployed and it will cause service unavailable. Especially web sites should be checked by some scraping tool like Selenium but it’s hard to do that for most start-up companies …

EC2 Service Discovery is very useful in the Prometheus configuration especially when the autoscale is used. However, some temporary or test servers which do not need to be monitored will be cause of unnecessary alerts. So, I added some settings to avoid it. For example, if I would like to eliminate instances which have …

Fluentd is necessary software for operating Kubernetes clusters. Variables in the Fluentd’s configs are useful because they reduce redundant writing and also it will come in handy to switch environments between development and production. For example, I configure the fluentd which is running on our Kubernetes cluster …

One day, I realized that the fluentd on our Kubernetes cluster was logging a lot of "invalid date" errors like this. 1#0 dump an error event: error_class=ArgumentError error="invalid date" …

When getting started to use AWS EKS for building Kubernetes clusters, we should consider the limitations of the number of IP addresses it depends on the instance size. Actually, I didn’t know about it because I just overlooked it on the official document. I know it was my mistake but it should be a blind spot for some …

When I was setting up HAProxy running on our Kubernetes cluster, I defined the log format as JSON and I got a lot of BADREQ logs with status code 400 as follows. 1{ 2 "conn": { 3 "act": 7, 4 "fe": 7, 5 "be": 0, 6 "srv": 0 7 }, 8 "queue": { 9 "backend": 0, 10 …

I've been operating the Kubernetes cluster in my company since I joined. Let me share my opinion about why I recommend Kubernetes to pre-growth start-up companies. Before I explain, I'm not crazy about Kubernetes. I understand to choose some other ways, depending on the company, the business environment, the team …

When I deploy some web application on the local Kubernetes cluster, I would like to test it like Without specifying a port number Via HTTPS Specify original FQDN not localhost For example, if I'm developing "www.example.com," I would like to test by the URL like https://www.example.work/. So, Let me share …