rainabba

A 1-liner bash function to provide basic non-zero exit retry with exponential backoff:

Minified

function retry_backoff {local m=${ATTEMPTS:-5};local t=${TIMEOUT:-1};local a=0;local e=1;while (($a < $m));do "$@";e=$?;if (($e == 0)); then break;fi;echo "Failure! Retrying in $t.." 1>&2;sleep $t;((a++));t=$((t*2));done;if (($e != 0));then echo "Max attempts reached!" 1>&2;fi;return $e; }

Use

retry_backoff $YOUR_COMMAND # default of 5 retries, starting with 1 second timeout

rainabba

First, credit to the answer at https://stackoverflow.com/a/55944296/901899

Second, if you aren't comfortable with an IIFE (immediately executed function), you will want to check out https://www.tektutorialshub.com/javascript/immediately-invoked-function-expressions-iife/.

Now, because switch() {} is a "statement" in JavaScript and not a function, it can't be IIFE executed with the following

let failure = ( switch(x) { default: return true; } )(x);

You will get: "Uncaught SyntaxError: Unexpected token 'switch'"

rainabba

/*
    To demonstrate the importance of understanding async execution order in the context of Express route handlers

    Try in your browser at https://runkit.com/rainabba/understanding-execution-order-in-express-handlers
**/


const express = require('express'),
    app = express(),
    PORT = 3000,

rainabba

console.time('full execution');
console.time('code block');
function showExecutionOrder(parm) {
    console.time('outside promise');
    new Promise((resolve, reject) => {
        console.time('inside promise');
        resolve(parm);
        console.timeEnd('inside promise');
    }).then((data) => {
        // Lookup mdn and invoke the account sync as required

rainabba

AWSTemplateFormatVersion: 2010-09-09
Transform: 'AWS::Serverless-2016-10-31'

# ... much omitted because it's unrelated

Globals:
  Api:
    OpenApiVersion: 3.0.1
    Auth:
      DefaultAuthorizer: NONE # AWS_IAM changed because we can't override on lambdas at this time. See https://github.com/aws/serverless-application-model/issues/984

rainabba

Parameters:
  StageName:
    Type: String
    Description: Major version changes should get new values (v1, v2, etc..)
    Default: v1
  
Conditions:
  CreateZone:
    !Equals [!Ref ZoneId, 'none']
  CreateCert:

rainabba

My use case was an array of objects coming from a document-store so they're extremely variable and we only want a sub-set of the returned fields. There are plenty of ways to go about this and I hope snippet will serve that purpose, but for me this was more about realizing the power of () to do a bit more with the Lambda passed to map(). I regularly pull up ANY chrome page, hit Ctrl+Shift+J and develop small snippets right in the console, which is what led to 1 of 2 discoveries today.

How I would have gone about this in the past

let result = { Items: [{ a: 1, b: 2, x: 3 }] },
 newList = result.map( o => { return { a: o.a, b: o.b }; );

My new solution

rainabba

## Below is a script/log (anonymized) of an instance where I'm getting "are the same file" errors from `cp`
##  Clearly they are not "the same file", but have identical contents and the 2nd is from a `git clone` command

#!/bin/bash
# me@myhost:/mnt/c/prj/someorg/some-project$ ls -lah;
ls -lah;
# total 0
# drwxr-xr-x 1 someuser root     512 Sep 15 10:26 .
# drwxr-xr-x 1 someuser root     512 Jun  3 06:48 ..
# drwxr-xr-x 1 someuser root     512 Apr 16 10:46 .vscode

rainabba

// SPOILER: Only 1 of these tests passes at this point and it bypasses
//    all the fluff and complication so it's the one I will end up using

const { expect } = require('code'),
	Lab = require('lab'),
	lab = exports.lab = Lab.script(),
	fs = require("fs"),
	path = require("path"),
	mkdirp = require('mkdirp'),
	rimraf = require('rimraf'),

rainabba

#!/bin/bash
#
#This script assumes very little other than a fresh Ubuntu install (using the Windows store) on Win10 1709 or newer with WSL installed already
#In Powershell, run the following to install WSL and Ubuntu
#
#Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux
#Invoke-WebRequest -Uri https://aka.ms/wsl-ubuntu-1604 -OutFile ~/Ubuntu.zip -UseBasicParsing
#Expand-Archive ~/Ubuntu.zip ~/Ubuntu
#~/Ubuntu/ubuntu.exe
#