barcodeweb

barcodeweb

what is this?

This is my first attempt at deploying a Go webservice in Cloudflare Workers. The webservice renders barcodes (Code 39 or Code 128) and QR codes.

trying it locally

This repository is setup to do everything via Docker containers, as I do not want to expose my Mac filesystem to npm.

The Makefile should be enough machinery to get you up and running.

make dev

Then, assuming that works, try browsing to: http://localhost:8787/c128/1234567890

URL structure

barcode types

• the first URL path component specifies the render type:
  • 2of5 for non-interleaved 2-of-5 barcodes
  • 2of5i for interleaved 2-of-5 barcodes
  • aztec for compact (4 layer) Aztec codes
  • c39 for Code 39 barcodes
  • c128 for Code 128 barcodes
  • qr for QR codes
• the remainder of the URL path component after the slash specifies the render content

query parameters

• width specifies width in pixels
• height specifies height in pixels

Note that each format has its own default sizing --- generally, 165x50 for barcodes and 200x200 for QR/Aztec.

Sizes smaller than 50x50 will be rejected.

examples

eg.

• http://localhost:8787/qr/https://github.com/jsleeio/barcodeweb/ (this is broken, as you'll see if you try it; see caveats section at the end of this file)

• http://localhost:8787/qr/hello-world

• http://localhost:8787/qr/hello-world?width=400&height=400

• http://localhost:8787/aztec/https://github.com/jsleeio/barcodeweb/ (this is broken, as you'll see if you try it; see caveats section at the end of this file)

• http://localhost:8787/aztec/hello-world

• http://localhost:8787/c128/123456&height=100

• http://localhost:8787/c39/123456&width=200&height=100

deploying to Cloudflare Workers

Some one-off preparation

1. create a worker named barcodeweb
2. create a Cloudflare API key using the worker template
3. put some Cloudflare configuration data in files in your $HOME:
   • in $HOME/shell-secrets/tokens/cloudflare/email, put your Cloudflare email address
   • in $HOME/shell-secrets/tokens/cloudflare/api-key, put your Cloudflare API key that you created in step 2
   • in $HOME/shell-secrets/tokens/cloudflare/account, put your Cloudflare account ID that you want to deploy into

The run-wrangler helper can be used for other Cloudflare Workers things if you need to use those also.

actually deploy

make deploy

That should be that!

caveats

handling of URLs with URLs in them

The Go net/http package tidies up request URLS, including coalescing consecutive slashes, which makes generating QR and Aztec images containing URLs impossible without moving the QR/Aztec content to a query parameter.

Specifically, URLs like https://localhost:8787/qr/https://my.website/ will generate a 301 redirect to https://localhost:8787/qr/https:/my.website/ --- the // has been replaced with /.

I currently don't see a way around this, as it even appears to do it when the // is URL-encoded. More info here: https://github.com/golang/go/issues/21955