Chapter 7. What deploying means — local and public

Key points

• Deploying = putting what is on your computer somewhere the world can reach
• A local environment (only you) and a public environment (everyone) are different things
• What goes onto the internet once cannot be fully taken back

Deploying is putting something into the world

Deploying means taking a program that ran on your own computer and placing it somewhere anyone in the world can reach.

The profile page from Chapter 5 opens in your own browser on a double-click, but nobody else can see it. Deploy it and a URL like https://... is issued; anyone who knows that URL can reach it, from anywhere.

It means roughly the same as "publishing" or "uploading", but engineers say "deploy" to carry the sense of placing files on a server and delivering them in a running state. The word appears constantly in the services you will use, so it is worth knowing.

Local environment versus public environment

The word "environment" comes up a lot in development. Two are enough.

Local environment — the program runs only on your own computer.

• nobody but you can see it
• you can break it as often as you like without troubling anyone
• it works without an internet connection

Try new things and make fixes here first. Failure affects only you; it is a place you can experiment in safely.

Public environment — after deployment, reachable by anyone in the world (also called production).

• anyone with the URL can reach it
• search engines may find it
• a change affects everyone looking at it

A public environment is not somewhere to put things casually. When you deploy, hold in mind that you are putting something into the world.

Knowing the weight of publishing

Deployment takes a few clicks once you know how. Which is precisely why people keep publishing things they later regret, lulled by how easy it is. The instinct learned in the previous part — asking yourself "would I be comfortable handing this to a third party?" — applies here too.

• What goes onto the internet cannot be made never to have happened. Even deleted, it may survive in screenshots, caches and search engines.
• People can reach it without knowing the URL. Published URLs follow guessable patterns and get picked up by search engines. "I only meant it for a few people" being seen by strangers is entirely ordinary.

A checklist before publishing

The publishing version of the safety checklist from the previous part. Run it before every deployment.

• Have I unintentionally included my real name, address, phone number or email address?
• Has information about a patient or a third party slipped into the text or the images?
• Is there a password or a secret mixed into the code?
• Have I asked myself: is this all right for anyone in the world to see?

Chapter 7 summary

• Deploying = putting what is on your computer somewhere the world can reach
• Local (only you) and public (everyone) are different things
• What goes out does not come back; make the pre-publication check a habit