AWS on Logan's Nest

Why Sentry events silently vanished from our Fargate Node app

Wed, 20 May 2026 00:00:00 +0000

TL;DR

Sentry’s Node SDK uses Node’s native https.Agent, which in Node 18+ does Happy Eyeballs dual-stack connections by default. When DNS returns AAAA records but the host (e.g. an ECS Fargate ENI) has no IPv6 routing, the IPv6 connect attempts don’t fail fast — they hang until the agent’s default 2-second timeout, producing AggregateError [ETIMEDOUT] and silently dropping the event. curl from the same host works fine because curl falls back to IPv4 in milliseconds. The fix is one line: tell the Sentry transport to force IPv4 via a custom httpModule.

Bypassing AWS Lambda's 4 KB env var limit

Thu, 07 May 2026 00:00:00 +0000

TL;DR

Lambda caps the total Environment.Variables map at 4 KB. There’s no AWS feature that auto-hydrates env vars from SSM at runtime. The cleanest way around it is a tiny Go binary wired up as AWS_LAMBDA_EXEC_WRAPPER that fetches SSM params at cold start and syscall.Execs the runtime, so the handler sees process.env.X exactly as if it had been set inline. Zero application changes; one Lambda layer.

CloudFront Anycast IP

Thu, 09 Oct 2025 00:00:00 +0000

I recently worked with a new AWS product called CloudFront Anycast IP, which costs $3,000/month. After testing it, I found the offering to be quite misleading, so I’m sharing my findings here.

CloudFront Functions with Dynamic Origin Pointing to Another CloudFront

Wed, 05 Feb 2025 00:00:00 +0000

At re:Invent 2024, CloudFront Functions introduced new features, including the ability to dynamically change the origin host.

Previously, this wasn’t possible as the Host header was read-only for CloudFront viewer requests.

Lookup CMK for a test in CDK

Tue, 06 Sep 2022 00:00:00 +0000

Add a CMK in CDK was easy, then when I looked into a way to reference the resource using findResources, faced constant failure as for some reason CDK can’t really pickup the key based on the alias.

fargate container healthcheck

Mon, 18 Jan 2021 00:00:00 +0000

Long story in short, unlike what https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_HealthCheck.html suggests, fargate doesn’t have curl.

For some reason it does have wget, so "command": [ "CMD-SHELL", "wget -q -O - ${healthcheck_endpoint} || exit 1" ] works as expected.

AWS TGW VPN using Unify UDM

Sat, 13 Jun 2020 00:00:00 +0000

Transit Gateway (TGW) is a managed cloud router service provided by AWS and it supports direct VPN attachment.

The setup is little bit tricky as UDM doesn’t support BGP.

1. Create a Customer Gateway
Select Dynamic routing and enter your router public IP

Amazon SES with Postfix in Ubuntu

Fri, 15 May 2020 00:00:00 +0000

Was looking at https://docs.aws.amazon.com/ses/latest/DeveloperGuide/postfix.html but it’s not really working as it’s missing some key commands.

Install packages apt install -y postfix libsasl2-modules\ select ’no configuration'

Config files

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cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf

in /etc/postfix/main.cf

Salesforce CLI with Docker in AWS

Fri, 28 Jun 2019 00:00:00 +0000

Auth was the tricky part as the normal auth requires a browser session rather than taking it from the CLI prompt.

Step 1. Create Dockerfile

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FROM node:9.9.0-alpine 
RUN npm install sfdx-cli --global 
RUN sfdx --version 
RUN sfdx plugins --core

Step 2. Generate auth URL from your laptop and push into SSM

AWS KMS - two liners

Thu, 18 May 2017 00:00:00 +0000

For binary encrypted output:

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aws kms encrypt --region ap-southeast-2 --key-id alias/blah --plaintext fileb://blah --output text --query CiphertextBlob | base64 --decode > blah.enc
aws kms decrypt --ciphertext-blob fileb://blah.enc --output text --query Plaintext | base64 --decode

For base64 encrypted output:

Curl net performance test

Thu, 15 Dec 2016 00:00:00 +0000

Print out CloudFront X-Amz-Cf-Id when response time is slower than set threshold.

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#!/bin/bash
 
output=($(curl -I -s -w "Time: %{time_total}\n" http://cf_url.here grep -e X-Amz-Cf-Id -e Time | awk {'print $2'}))
 
id=${output[0]}
time=${output[1]}
compare=0.01
 
if (( $(echo "$time > $compare" |bc -l) )); then
 echo $time - $id >> test_results.txt
fi

Small variation (unrelated to CF)

MongoDB to DynamoDB

Wed, 08 Jun 2016 00:00:00 +0000

Attempted to convert rather large mongo dump to dynamo.

Seems like AWS data pipeline is most elegant way to do this if one can workaround with dynamo non-standard json format issue.