grieve54706

Pod watcher

K8s has metrics server to provide cpu and memory usage of pods. Default 60 seconds, can be changed using --metric-resolution flag. Official are not recommending setting values below 15s, as this is the resolution of metrics calculated by Kubelet.(ref1, ref2)

So I create this tool to watch cpu and memory and log peak usage of pods.

How to install

// instal node 17
bash <(curl -sL https://gist.githubusercontent.com/grieve54706/acd9c1a411adab38c4f61f2b1497769f/raw/d42e76f3f8a3aaadf3055094df8c7dab3c688e2f/upgrade-node.sh)

kevinwucodes

Notes

Koa middleware cascade in a more traditional way as you may be used to with similar tools - this was previously difficult to make user friendly with node's use of callbacks. However with async functions we can achieve "true" middleware. Contrasting Connect's implementation which simply passes control through series of functions until one returns, Koa invoke "downstream", then control flows back "upstream".

The following example responds with "Hello World", however first the request flows through the x-response-time and logging middleware to mark when the request started, then continue to yield control through the response middleware. When a middleware invokes next() the function suspends and passes control to the next middleware defined. After there are no more middleware to execute downstream, the stack will unwind and each middleware is resumed to perform its upstream behaviour.

const Koa = require('koa');
const app = new Koa();

rxaviers

People

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scy

Opening and closing an SSH tunnel in a shell script the smart way

I recently had the following problem:

• From an unattended shell script (called by Jenkins), run a command-line tool that accesses the MySQL database on another host.
• That tool doesn't know that the database is on another host, plus the MySQL port on that host is firewalled and not accessible from other machines.

We didn't want to open the MySQL port to the network, but it's possible to SSH from the Jenkins machine to the MySQL machine. So, basically you would do something like

ssh -L 3306:localhost:3306 remotehost