Smokeping is a self-contained network monitoring app , capable of monitoring using ICMP/Ping, HTTP, DNS -- as well as other signals generated from CLI monitoring tools (e.g. curl, dig, mtr etc). It provides a web-based monitoring UI to chart the probe measurements so no further monitoring apps (like Prometheus) are needed.

Running smokeping on a $5 Raspberry Pi Zero is a fun experiment in lightweight computing . Using Apache Mod FastCGI makes the app usable on the meager hardware.

By the end of the exercise you'll have the smokeping probes running to test network performance and the UX available on your …

Every app has that last inch (or mile) of code that's not covered by tests. Usually it's an interactive cycle of compile-run-inspect on the command line like

You Test

 curl -X POST https://reqbin.com/echo/post/json

👀 You Expect:

{"success":"true"}

Despite having 3-4 testing frameworks for unit tests, e2e, regression etc-- there's always a gap where you find yourself re-playing commands in the terminal to test.

A common case is 🔥firefighting where ad-hoc tests are needed to validate an emergency config change or deployment.

Not only is this a waste of time, it's error prone and reduces the …

Recently an old friend, with great experience as an IC, PM and EM, called me to ask for some advice. He had been running his business for a while and took up a new role as an engineering manager after some time. "What areas do you focus on as an EM?, particularly when joining a new team".

I divided the conversation into three pillars: strategy & inventory, technical (aka going deep) and career / personal

Any given day, week or month will include some of these. Some periods will emphasize one or the other more heavily.

Strategy

Strategy is about helping the …

Signal Vs Noise

One responsibility of engineers & especially leads is managing many channels of signals : emails, blog posts (internal and external), tags , push notifications, group chats, alerts from dashboards and more.

These signals tend to scale exponentially to the number of projects & people that you are responsible for.

Quickly you'll need to set up a system to make sure that you are receiving high-signal information and filtering out low-signal noise. How do you do that?

For each channel, it's important to set up and continuously refine filters that matter to you.

Each system typically has filtering that can be configured …

Directory layouts are like log cabins that start from a basic shed, gradually adding a room at a time. When you start out on UNIX, everything gets thrown in your home directory. Over time you start to develop a structure for your sources, binaries, projects, data files (like CSV, images, tar files), config, etc

My layout is called TDL -- because it allows me to juggle open source projects, partnerships and jobs in a consistent structure across machines and time.

:::bash
~/
│── .cfg          # bare git repo with my dotfiles
│── local         # e.g. make install --prefix=~/local
│     - lib, bin, man  
│── .trash        # files to …

Cloud instances bill by the hour (or the minute) – and right now you're burning money. Use snooze to auto-shutdown your instances in 45 minutes.

Add snooze to your ~/.bashrc

alias snooze='sudo shutdown -c ;  sudo shutdown -h +45 &'
snooze

When you want to extend your session, run snooze

Broadcast message from ec2-user@ip-172-31-43-250
    (/dev/pts/1) at 2:50 ...

The system is going down for halt in 45 minutes!

How does this work?

shutdown -c cancels the shutdown, and shutdown -h +45 schedules a shutdown in 45min.

How can we automate this?

Stay tuned !

I work from about 7 different machines, including 3 laptops, ipad, chromebook and a PC desktop. Usually this means keeping credentials, config, build dependencies and IDEs in sync across all 3--and the iPad & Chromebook just can't run my dev environment

I considered a few options to enable seamless work across devices

Solution

1. Launch Cloud9 Environment on …

📓 The Gist

You may think your 100mB Alpine images are small--but how about 100kB? Smaller images ship more quickly, and contain fewer attack vectors. Moreover, by optimizing images, you discover and isolate exactly what is needed for your app to run.

Let's Optimize.

There are two key characteristics of scratch-based docker images: 1. The Dockerfile has two build stages: * a builder--which contains all of the build dependencies including source, libraries and tools and.. * a final image, containing the binary and any run-time dependencies (config files, certificates and dynamically linked libraries) 2. The final image is FROM scratch -- the empty docker …

In Part 1, we completed our development environment, including setting up Hugo and our repo.

Here we'll publish our site to Firebase Hosting, and create the CI tools on Google Cloud Build to build and publish upon push.

Open Your Cloud Shell

In Part 1, we enhanced our cloud shell with hugo and set up our repo. In Part two, we'll use it to create the builder and configure hosting.

See the Quickstart for complete instructions

Create a Firebase Site & Configure Your Project

First, authenticate your cli

:::bash
# --no-localhost let's us authenticate our cloud shell by code
$ firebase login …

Here's a benchmark comparing pi-hole running on a Pi Zero (with USB ethernet) vs a Pi 3b+.

tl;dr There was negligible performance difference for blocked domains, but a measurable difference in mean for forwarded + cacheable domains. Although the Pi 3b+ has a 11ms better mean response time for forwarded queries, the P95 for pi zero is better in both blocked and forwarded queries.

I would recommend using the Pi Zero.

Hypothesis

Prior to the experiment, I assumed that the pi zero would be 30-50% slower in all cases, and that stddev would be larger (worse & more erratic latencies).

Hardware …

Here's the fastest way to get your PHP app running. No MAMP, WAMP, apache or any of that nonsense.

Moreover, it allows you to run multiple projects independently.

I'm assuming you have docker.

tl;dr

This runs the php docker image, mounts the current directory, and spins up a server on port 8086

$ docker run -v $(pwd):/www -it -p8086:8086  php:5.6-alpine sh -c "cd www; php -S 0.0.0.0:8086"

The Full Version

Create your index.php

$ cat > index.php
<html><body><h1><?php print("Hello World!") ?> </h1></body></html>
CTRL-D

Run the Server

$ docker …

Next time you create a post with code snippets--like here on dev.to or stackoverflow--consider sharing a working and buildable gist along with it. By doing so, others can clone, reproduce your results, and commit new variants much more easily.

With the process below, your gist becomes a sharable laboratory. Since the gist contains all of the code variants and test cases, any team member can create a variant and run the tests against all existing variants.

In the examples below, we were discussing performance differences between short Perl & Golang snippets, presumably doing the same thing. The original variant had …

There was a great discussion a year ago about how fast gnu's version of "yes" is. If you're unfamiliar, yes outputs y indefinitely.

yes |head -5
y
y
y
y
y

The key takeaway was that write is expensive and writing page-aligned buffers is much faster. The is true across languages, so let's see how to do it properly in go.

If you're shocked or impressed by the results, let's see you do it in your language -- post your results in the comments.

First, our benchmark C code from last-year's post.

/* yes.c - iteration 4 */
#define LEN 2
#define TOTAL …

GCP resources are organized into projects -- all resource IDs and IAM principles are grouped under a project ID. This means that by default roles assigned to a principle (e.g. a user or service account) are scoped only to project resources. This can be tricky if say your images are in one project's storage bucket and your app is running in another

If you want to provide a service principle in one project access to resources in another , the approach is not obvious, nor is it well documented.

Below we'll talk about the most direct way, which works for projects …

Static site frameworks like Hugo allow you to manage content with Markdown and publish content via scalable hosting platforms like Firebase hosting. Uptime, performance and operations cost per user can't be beat -- you can easily hit millions of pageviews for less than $10/ month

In this tutorial we'll make a production-ready personal website site, that supports multiple collaborators, built using Hugo. Moreover, we'll publish with the free-to-start Firebase Hosting CDN, and build automatically using Google Cloud Builder.

Prerequisites

1. A Google Cloud Platform Account & Project -- You can use the free tier
2. A Firebase project -- also free
3. Access to the Google Cloud …

Instrumentation is a critical part of any application. Along with system counters like cpu, heap, free disk, etc-- it's important to create application-level metrics to make sure health is measured closer to your customer's experience.

Example metrics could be user-registration, password-change, profile-change, etc. If you see a major spike or dip in these metrics, a wider problem could be indicated.

For this example a custom metric was needed, and no infrastructure was in place for harvesting it (e.g. collectd). Golang is handy for creating an easy-to-install daemon which performs the measurement and periodically harvests the data into stackdriver.

The …

Blink security cameras are an affordable home security camera system. Although they lack a formal public API, inventive devs have reverse-engineered their private API to allow for better integration.

Here we'll use AWS IOT Core, Lambda and node-blink-security to arm and disarm Blink security cameras using an AWS IOT Button.

Activating Your IOT Button

The IOT Button must be configured to your account, which includes joining it to your wifi access point, and installing the client certificates.

The easiest way to perform activation is by using the AWS IOT Button App for Android or IOS. Complete instructions are found on …

Like me, you're probably more comfortable on a CLI. Here's a quick way to use docker to set up a Bitcoin Wallet and trade Bitcoin for free on Testnet with Electrum. You can use the same tools to manage your real Bitcoin wallet too.

Setup

Make sure you have Docker for your OS ( Mac, Windows, Linux)

Run the electrum-cli docker image

Electrum is a python-based Docker wallet with a both a gui and good cli. I've put together electrum-cli, a lightweight Alpine-linux Docker image with Electrum signed and installed with jq.

docker run -it tonymet/electrum-cli

Create a wallet

First …

Usually setting up the build dependencies is a major part of each build job. Thankfully, Atlassian's Bitbucket Pipelines, the new CI platform that integrates into Bitbucket, supports custom docker images.

To configure the build pipeline, you create bitbucket-pipeline.yml . This one uses our custom image (built below) and triggers builds whenever a releases-* tag is pushed.

image: tonymet/tonym.us:latest
pipelines:
  tags:
    release-*:
      - step:
          script:
            - make sync_down_images
            - make s3_upload

That first line is the magic part -- you can run ANY public docker image from dockerhub (and private ones as well with further setup).

Building a Static …

A common migration pattern when moving to docker includes running some systems (e.g. dev, staging or a prod canary) on your docker image while the production app is still running your traditional tgz artifacts (e.g. your node app with node_modules)

Let's create a travis build that creates two artifacts: (1) your docker image and (2) a tgz from the docker container.

Let's assume you have a basic dockerfile with your app.js and a package.json. The key is that the app is built into /usr/src/app

FROM node:4

RUN mkdir -p /usr/src/app …

Google App Script is a little-known, yet powerful development platform for enhancing and automating google services. I use it for administration and building custom tools. Here are some things I've used it for

• a web app that scans emails for certain patterns and puts the results in email
• index email into a sql db to build charts & reports (e.g. 7d volume, top senders)
• automate account settings changes & cleanup
• bulk migration of email between accounts or from shared accounts to groups
• various google spreadsheet formulas
• various google docs macros like timestamps

Sadly, the platform is a bit tricky to set …

2016 may be the year of free SSL, and AWS ACM (AWS Certificate Manager) is a great offering for Cloudfront & ELB users (most web apps).

Not only is it free, but it's also the simplest certificate management platform

• request a new certificate in minutes
• no server config needed
• no certificate , chain or private key management
• automatic certificate rotation

Here's how to create a certificate and then install it onto your cloudfront distribution.

Requesting a New Certificate

aws acm request-certificate --domain-name \*.mydomain.com --subject-alternative-names  mydomain.com
{
    "CertificateArn": "arn:aws:acm:us-east-1:OOOOOOOOOOOO:certificate/c3d15000-230c-4000-8000-a600000"
}

Activating the Certificate on Cloudfront

This part …

Varnish is an amazing platform -- it can easily help you handle 100x traffic and is easy to add to your existing frontend or API layer with little to no change to your app.

Here we'll go over some neat tricks leveraging chef, the AWS Opsworks API and the opsworks configure lifecycle event to create a lighting fast load balancer & reverse proxy that automatically updates itself.

Setup

1. Create a new varnish layer that installs the varnish and jq packages

2. Activate custom cookbooks. It's easiest to just use s3 deployments so you don't need a separate git repo.

The varnish::backends recipe …

AWS announced recently that it's EC2 Container Registry (ECR) is now available. ECR simplifies hosting private images. Previously, you had to manually push your docker.io credentials to each EC2 instance -- likely a deliberate pain-point encouraging you to use ECR. With ECR, EC2 container hosts can easily fetch private images using IAM authentication.

Here are some of the gotchyas and stumbling blocks to help you get your repository up quickly and painlessly.

Prerequisites

1. aws-cli should be 1.9.15 or greater.

# check Version
$ aws --version
aws-cli/1.9.15
# update via homebrew (osx) if needed
$ brew update
$ brew …

We all know that no ports should be open to the internet for development purposes, but for convenience it's common to find a security group with port 22 (SSH) open to 0.0.0.0/0 . Even narrower ingress rules can create backdoors.

Here we'll show you how to create an auto-updating security group that adds your active WAN IP address when you connect. This way, only your active IP is authorized.

Create the "development" security group with no ingress

aws ec2 create-security-group --group-name=development --group-description="ssh access for my dev machine"

Create a limited role …

It's hard to strike the right balance with admin rights--either the rights are too strict and people can't get work done or they're too lenient and you have security issues.

As a compromise, AWS provides the AssumeRole feature which lets admins temporarily escalate their role to perform a task.

It's important when setting this up that you alert the team when it's used. Here we'll talk about how to set up the roles, give teams access to the roles and create an alert system when the roles are assumed.

Create The Temporary Admin Role

Use the IAM console to create …

Often your creative team will produce master videos in 4k or 1080p, but you need to downcode these videos into 720p/1080p for web broadcasting. Here we automate transcoding of masters into web-friendly formats like 720p h264 mp4 & webm.

AWS Elastic Transcoder is a cloud video transcoding service. At it's simplest it transcodes video files from one bitrate, framerate, codec, container, etc--into another. By default you trigger new jobs either manually in the aws console or via the rest API. And naturally all inputs & outputs are saved in S3.

Transcoder setup includes creating a pipeline and presets. Then for each …

By default Wordpress uses it's own pseudo-cron which triggers with every request. Obviously this is wasteful since (a) the queue needs to be inspected with every GET and (b) jobs like publishing articles will interfere with serving content.

Some suggest calling the wp-cron.php GET request with curl in a cron like this

* * * * * curl http://www.mysite.com/wp-cron.php

but that's sub-optimal since it needlessly ties up a worker during the cron execution.

If you're using chef or Opsworks, here's a tidy way to install the system cron to execute without interfering with your webserver.

First, disable the Wordpress …

Redirects can account for a significant share of direct traffic so taking a few minutes to optimize them is worthwhile.

Using Cloudfront & S3 for redirects will improve responsiveness, reduce server load and improve management (since they are managed via aws-cli or the console).

Let's say you have a typical .htaccess redirect like this.

RewriteEngine On
### re-direct to www
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Or worse, it could look like this in your index.php

$protocol = (@$_SERVER["HTTPS"] == "on") ? "https://" : "http://";

if (substr($_SERVER['HTTP_HOST'], 0, 4) !== 'www.') {
    header …

Continuing the relentless quest to keep my phone speedy, I stumbled upon a developer tool that is useful to anyone needing to troubleshoot a slow, short-living or overheating phone -- Battery Historian

Battery Historian shows you a much more detailed and informative battery stats chart, highlighting the individual apps and sync services which are keeping your phone awake/busy in the background. It also shows network, wifi status, gps and more.

Using this tool I identified that the Facebook Messenger app was waking up to send stats. Also, Google+ was syncing for ~40s in the bakground at times.

tl;dr

$ git …

I have a frustrating relationship with my phone's performance. I can cleanup my phone for a few days, but it tends to revert to being sluggish within no time. I've had dozens of devices and they all suffer from this.

There's a lot of voodoo about Android Performance and Battery life--task managers, factory resets, etc.

Here's a more developer-oriented process using adb .

Using ADB to identify process hogs

By connecting your device to the Android SDK, you can use ADB to identify process hogs. If you can, just remove the app. Otherwise, delete it's data (see pm clear below)

$ adb …

I was desperate to try Hangouts 4.0 for Android, but suspicious of side-loading. I wanted to verify the APK signature cert had Google's fingerprint of

38:91:8A:45:3D:07:19:93:54:F8:B1:9A:F0:5E:C6:56:2C:ED:57:88

Here's how to check the signatures on an APK, as usual, in shell functions (JDK needed)

apk-check () {
    jarsigner -verify -verbose -certs $1
}

apk-print-cert () {
    keytool -list -printcert -jarfile $1
}

# usage
# make sure it's verified
$ apk-check *apk|grep verified
  s = signature was verified
jar verified.
# show …

Here's a great example of using the aws-cli to speed up your life. Uses jq and aws-cli

  # bash / zsh function
  function opsworks-hosts-prod () {
    aws opsworks describe-instances --stack-id=fffff-fffff-ffff-fff-fffffff | jq '.Instances[].PublicDns' | grep -v null | sed s/\"//g
  }
  # usage
  $ opsworks-hosts-prod
  XXXXX.compute-1.amazonaws.com
  XXXXX.compute-1.amazonaws.com
  XXXXX.compute-1.amazonaws.com
  XXXXX.compute-1.amazonaws.com

I was chatting with a buddy who was moving his web sites from dedicated hosting to AWS. Let's just say the FTUE isn't great. That triggered a quick brain-dump of what you should do when you first get started with AWS.

• understand pets v cattle. In aws all resources should be "cattle", not pets. Periodically terminate instances to test this.
• activate cloudtrail (in all regions). Use Loggly to index cloudtrail (free or ~$20/mo)
• create restricted IAM users. Never use your root acct. Activate MFA.
• Use IAM ec2-instance roles instead of stored credentials whenever possible.
• Get familiar with IAM management …