Сhangelog: slots and tags update

tip

Take a look at the slots and tags guide page for practical instructions on using the system.

Motivation

When we initially built the original deployment flow versions felt appropriate. A simple number you could increment on each deployment if necessary. This worked well in simple scenarios, but over time this gradually became more difficult to manage for those of you with any kind of deployment complexity.

At the same time it became clear that our solution to endpoint management, allowing you to mark a squid as production and create a permalink, was equally powerful in basic scenarios but limited as requirements grew.

It became clear that was lacking here was the ability for larger teams to collaborate effectively. Our goal with these changes is to provide the power and flexibility that more complex deployment flows need.

Concepts

Concepts	Before	After
Version	Existed	Removed (replaced with slots)
Slot	Did not exist	Introduced (unique identifier for configs)
Production alias	Existed	Deprecated (use tags)
Tag	Did not exist	Introduced (user-defined labels for deployments)
Reference	Existed	Exists, but the format has changed

New concepts are explained in detail in the guide.

Format changes

Value	Before	After
Version	Must be a number	Deprecated
Slot	Did not exist	A string of up to six lower case alphanumeric characters, dashes allowed
Tag	Did not exist	A string of lowercase alphanumeric characters, dashes allowed
Reference	<name>@v<version>	[<org>/]<name>(@<slot>|:<tag>)
Canonical URL	https://<org>.squids.live/<name>/v/v<version>/graphql	https://<org>.squids.live/<name>@<slot>/api/graphql
Production URL	https://<org>.squids.live/<name>/graphql	Deprecated. See also backwards compatibility.
Tag URL	Did not exist	https://<org>.squids.live/<name>:<tag>/api/graphql

Manifest changes

Field	Before	After
name	Present	Present
version	Present	Deprecated (mapped to slot)
slot	Absent	New field (unique identifier)
tag	Absent	New field (user-defined label)

CLI changes

Changes to CLI behavior are rather extensive:

• New flags --name/-n, --tag/-t, --slot/-s, --reference/-r have been added to nearly all commands.
  • For sqd deploy they now can override their corresponding manifest fields. Heterogenous overrides also work: -t in CLI overrides slot: in manifest, and -s overrides tag:.
  • For other commands (sqd logs, sqd restart etc) they allow for flexible specification of deployment.
• New commands sqd tags add and sqd tags remove have been added.
• The sqd prod command has been removed.

Here's what the new commands look like for some common tasks:

Action	Before	After
Deploying prod version	sqd deploy . && sqd prod my-squid@v1	sqd deploy . --add-tag prod
Promoting to prod	sqd prod my-squid@v1	sqd tags add prod -n my-squid -s v1
Marking a deployment as a "dev" version	Was not possible	sqd tags add dev -n my-squid -s v1
Updating the "dev" version	Was not possible	sqd deploy . -t dev
Fetching logs	sqd logs my-squid@v1	sqd logs -n my-squid -s v1

Cheatsheet

Add tag testtag to the deployment of my-squid running in slot v1

sqd tags add testtag -n my-squid -s v1

(Re)deploy the squid and immediately assign the tag testtag to the deployment

sqd deploy . --add-tag testtag

• The squid will be redeployed if one of the tag:, slot: or version: fields are defined in the manifest and the Cloud already has a deployment that matches the reference.
• If the fields are undefined or there's no matching squid in the Cloud, a new deployment will be created in a new slot.
• Tag testtag will be assigned to the slot of the (possibly new) deployment.

Update the deployment tagged dev

sqd deploy . --tag dev

• If there's a deployment tagged dev, it will be updated.
• Otherwise, the command will exit with an error.

Read logs of the deployment of my-squid tagged prod

sqd logs -n my-squid -t prod

Backwards compatibility

Here are the measures we've taken to make the migration smoother:

• Existing deployments lose their versions; instead, they are assigned to the corresponding v<version> slots. New deployments that specify version: in the manifest will be assigned to the v<version> slot, too. Hence, for the time being the lines

  version: 42
  and

  slot: v42
  in the manifest file are equivalent.
• Tag prod has a special meaning for the duration of the transition period: deployments that have it are made available via old-style production URLs.
• Tag prod is assigned to all existing deployments with production aliases.
• You can, for the time being, add an old-style production URL to any deployment - just assign the prod tag to it.

FAQs

Do I need to redeploy anything?

No. But we suggest you take a look at the Backwards compatibility section.

We really like versions, they work well for us, do we need to change our workflow?

No, you don't need to change your workflow at all! Your version will be migrated into the new slot field, and slots are a just an arbitrary string between 2 and 6 characters in length. Our goal was to expand functionality rather than remove it.

Why should I use tags? Convince me.

Tags serve two key roles. Firstly as a labelling mechanism, this allows teams to explicitly describe what each squid does and what stage it's at in development. Secondly as a way to preserve urls across slots. Tags act as an alias by creating a unqiue endpoint for each tag. This allows you to migrate a consistent endpoint across slots with ease.

Will any of my endpoints change when this is released?

No. Every endpoint will remain unchanged.

Where should I send my feedback on the new system?

We're keen to hear from you. Come talk to us in the SquidDevs Telegram channel.