cheatsheets

A personal collection of incantations for various technologies.

AWS CLI

ECR login

PROFILE=stg
REGISTRY_ID=123123123123
aws ecr get-login-password --region us-west-2 --profile $PROFILE | docker login --username AWS --password-stdin $REGISTRY_ID.dkr.ecr.us-west-2.amazonaws.com

Get ECR image versions for myorg/myimage sorted by creation date

Outputs a JSON string array. Useful for creating a Jenkins UI to pick a release version.

REPO_NAME=myorg/myimage
aws ecr describe-images --repository-name $REPO_NAME \
  --profile=stg --region=us-west-2 \
  --query 'reverse(sort_by(imageDetails,& imagePushedAt))' | \
  jq 'map(.imageTags) | add'

[
  "0.15.5",
  "0.15.4-canary-813d69f",
  "0.15.3",
  "0.15.2-canary-4c3dbfe",
  "0.15.2",
  "0.15.1",
  "0.15.0"
]

Docker

Delete all images for repo myorg/myimage before version x.y.z

Useful for managing disk space in CI environments.

VERSION=1.0.0
REPO_NAME=something.amazonaws.com/myorg/myimage
TAG_NAME=$REPO_NAME:$VERSION
OLD_IMAGES=$(docker images -a -q --filter=before="$TAG_NAME" --filter=reference="$REPO_NAME")
docker rmi $OLD_IMAGES

Build a Dockerfile without a build context

Useful if you don't need a build context. Copying the entire current directory wastes time.

docker build -t myimage:latest - < Dockerfile

Mac OS

Always Show Scrollbars

Enabling this setting is helpful for spotting duplicate, nested scrollbars in HTML documents when overflow: scroll; is set (overflow: auto is preferred).

• Click the Apple menu at the top-left of the screen, then select System Preferences.
• Next, select the General preferences pane; it’s the very first one, up at the top.
• Under the “Show scroll bars” heading, you’ll find three options: “Automatically based on input device,” “When scrolling,” and “Always.”
• Go ahead and select that last “Always” option. You’re done!

Source: https://heresthethingblog.com/2015/03/10/mac-tip-macs-scroll-bars

NodeJS

Increase Memory Limit (16gb)

Add to ~/.bash_profile:

export NODE_OPTIONS=--max_old_space_size=16384

Mount and unmount RAM drive

For better File I/O (npm install, etc).

Usage:

npm run mount # Move folder to RAM disk
# ...Do work...
npm run unmount # Move folder back to HDD

package.json:

{
  "scripts": {
    "mount": "./scripts/mount.sh",
    "unmount": "./scrips/unmount.sh",
  }
}

scripts/mount.sh:

#!/usr/bin/env bash

# Log Each command
set -x

DISK_NAME=ExampleRAMDisk
REPO_ROOT="$(dirname $( cd "$(dirname "$0")" ; pwd -P ))"
REPO_FOLDER_NAME="$(dirname $REPO_ROOT)"

# Test for existence of RAM disk (0 = exists)
diskutil info /Volumes/$DISK_NAME >> /dev/null
RAMDISK_EXISTS=$?

if [[ $RAMDISK_EXISTS != "0" ]]; then
  echo "No RAMDisk. Provisioning..."
  # 8 GB Ram Disk mounted at /Volumes/$DISK_NAME
  diskutil erasevolume HFS+ '$DISK_NAME' `hdiutil attach -nobrowse -nomount ram://16777216`
  # recursively remove all node_modules folders and typescript cache files
  find . -name 'node_modules' -type d -prune -exec rm -rf '{}' +
  cd ..
  mv $REPO_ROOT /Volumes/$DISK_NAME
  ln -s /Volumes/$DISK_NAME/$REPO_FOLDER_NAME $REPO_ROOT
  cd $REPO_ROOT
  rm .original_path
  echo "$REPO_ROOT" > .original_path
  exec bash -l # Resets PWD
else
  echo "RAMDisk exists. Skipping provisioning."
  exit 0
fi

scripts/unmount.sh:

#!/usr/bin/env bash

# Log Each command
set -x

REPO_ROOT="$(cat .original_path)"
DISK_NAME=ExampleRAMDisk
REPO_FOLDER_NAME="$(dirname $REPO_ROOT)"

if [[ -z "$REPO_ROOT" ]]; then
  echo "Not sure where to restore repo back to."
  exit 1
fi

rm $REPO_ROOT

# recursively remove all node_modules folders
find . -name 'node_modules' -type d -prune -exec rm -rf '{}' +

mv /Volumes/$DISK_NAME/$REPO_FOLDER_NAME $REPO_ROOT
rm -rf /Volumes/$DISK_NAME/**

cd ~
cd $REPO_ROOT
diskutil unmountDisk force /Volumes/$DISK_NAME/ &
exec bash -l # Resets PWD

OS Commands

Disk Space Commands

Which file system a folder belongs to

df .

Size of all non-hidden files in a directory

sudo du -sh * | sort -n

Size of all directories

sudo du -sh .[!.]* * | sort -n

Size of all file systems

sudo df -h

Self-signed SSL Cert one-liner

Useful for spinning up an https server.

openssl req -newkey rsa:2048 -new -nodes -x509 -days 3650 -keyout key.pem -out cert.pem -batch -subj '/CN=0.0.0.0/C=US'

To start server:

npm i -g http-server
http-server -S -C cert.pem --cors

Delete directories by glob pattern

Useful for clearing unused folders on gh-pages branches.

find . -type d -name "*-canary-*" -exec rm -rf {} \;

Use jq to edit import maps

Useful for updating import map files from a CI/CD pipeline. This will work for over-writing an existing map, or adding a new one.

echo '{"imports":{}}' > importmap.json
ARTIFACT_NAME=@myorg/microfrontend
SEMVER=0.1.2
jq --arg artName "$ARTIFACT_NAME" --arg semVer "$SEMVER" '.imports[$artName] = "//cdn.company.com/" + $artName + "/" + $semVer + "/main.js"' importmap.json

Output:

{
  "imports": {
    "@myorg/microfrontend": "//cdn.company.com/@myorg/microfrontend/0.1.2/main.js"
  }
}

SSH

Persist key password

Prevents being promoted for key password. Saves time.

ssh-add -K ~/.ssh/id_rsa

SVG

Transparent mask

Useful for subtracting one vector from another.

<svg version="1.1" xmlns="http://www.w3.org/2000/svg" width="100" height="100">
  <defs>
    <mask id="mask" x="0" y="0">
      <rect fill="white" width="100%" height="100%" fill-opacity="1" />
      <circle cx="50" cy="50" r="20" />
    </mask>
  </defs>
  <rect style="mask: url(#mask)" x="0" y="0" width="100%" height="100%" fill="#00f" />
</svg>

Resize canvas to element

Useful for removing extraneous negative space bordering SVG content

• Open SVG in Inkscape
• Select all items in layer ⌘ A
• Resize canvas ⌘ ⇧ R

Add viewBox attribute (if missing)

Specifying viewBox is helpful when manually setting height and/or width on an <svg> element.

• Open SVG in Inkscape
• Save As > Optimized SVG
• On "SVG Output" tab, check Enable viewboxing

Animated, infinitely repeating gradient

• https://codepen.io/hujambo-dunia/pen/jaxLZw

<svg xmlns="http://www.w3.org/2000/svg" width="200" height="50" version="1.1" viewBox="0 0 200 50">
  <defs>
    <linearGradient id="gradient" x1="0%" y1="0%" x2="100%" y2="0">
      <stop offset="0%" style="stop-color: red;" />
      <stop offset="14.28%" style="stop-color: orange;" />
      <stop offset="28.57%" style="stop-color: yellow;" />
      <stop offset="42.85%" style="stop-color: green;" />
      <stop offset="57.14%" style="stop-color: blue;" />
      <stop offset="71.42%" style="stop-color: indigo;" />
      <stop offset="85.71%" style="stop-color: violet;" />
      <stop offset="100%" style="stop-color: red;" />
    </linearGradient>
    <pattern id="pattern" x="0" y="0" width="300%" height="100%">
      <rect x="0" y="0" width="150%" height="100%" fill="url(#gradient)">
        <animate attributeName="x" from="0" to="150%" dur="2.5s" repeatCount="indefinite" />
      </rect>
      <rect x="-150%" y="0" width="150%" height="100%" fill="url(#gradient)">
        <animate attributeName="x" from="-150%" to="0" dur="2.5s" repeatCount="indefinite" />
      </rect>
    </pattern>
  </defs>
  <g fill="url(#pattern)">
    <rect x="0" y="0" width="200" height="50" />
  </g>
</svg>

VirtualBox

Access Server on Host from Guest

Use IP Address 10.0.2.2:{portNumber}.

Increase Graphics memory beyond GUI max of 128 MB (to 256 MB)

vboxmanage modifyvm "nameOfVM" --vram 256

Set scale factor to 2x (for Retina displays)

VBoxManage setextradata "nameOfVM" GUI/ScaleFactor 2

Add additional CPUs (6)

VBoxManage modifyvm "nameOfVM" --cpus 6

Add additional RAM (8 GB)

vboxmanage modifyvm "nameOfVM" --memory 8192

Install Guest Additions

vboxmanage unattended install "nameOfVM" --install-additions --iso=/Applications/VirtualBox.app/Contents/MacOS/VBoxGuestAdditions.iso

Enable 2d acceleration

VBoxManage modifyvm "nameOfVM" --accelerate2dvideo on

Enable 3d acceleration

VBoxManage modifyvm "nameOfVM" --accelerate3d on