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Showing posts from November, 2015

Initial experiences with the Prometheus monitoring system

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I've been looking for a while for a monitoring system written in Go, self-contained and easy to deploy. I think I finally found what I was looking for in Prometheus, a monitoring system open-sourced by SoundCloud and started there by ex-Googlers who took their inspiration from Google's Borgmon system.

Prometheus is a pull system, where the monitoring server pulls data from its clients by hitting a special HTTP handler exposed by each client ("/metrics" by default) and retrieving a list of metrics from that handler. The output of /metrics is plain text, which makes it fairly easily parseable by humans as well, and also helps in troubleshooting.

Here's a subset of the OS-level metrics that are exposed by a client running the node_exporter Prometheus binary (and available when you hit http://client_ip_or_name:9100/metrics):

# HELP node_cpu Seconds the cpus spent in each mode. # TYPE node_cpu counter node_cpu{cpu="cpu0",mode="guest"} 0 node_cpu{cpu…

Why I like golang: a programming autobiography

Tried my hand at writing a story on Medium.

Notes on testing in golang

I've been doing a lot of testing of APIs written in the Go programming language in the last few months. It's been FUN! Writing code in Golang is also very fun. Can't have good code quality without tests though, so I am going to focus on the testing part in this post.


Unit testing
Go is a "batteries included" type of language, just like Python, so naturally it comes with its own testing package, which provides support for automated execution of unit tests. Here's an excerpt from its documentation:
Package testing provides support for automated testing of Go packages. It is intended to be used in concert with the “go test” command, which automates execution of any function of the form func TestXxx(*testing.T) where Xxx can be any alphanumeric string (but the first letter must not be in [a-z]) and serves to identify the test routine. The functionality offered by the testing package is fairly bare-bones though, so I've actually been using another package call…