change Version to struct, prevent misconfiguration of VersioningOverride

[carlydf]

READ BEFORE MERGING: All PRs require approval by both Server AND SDK teams before merging! This is why the number of required approvals is "2" and not "1"--two reviewers from the same team is NOT sufficient. If your PR is not approved by someone in BOTH teams, it may be summarily reverted.

What changed?

• Make override a one of and add different pinned override types.
• Change version from string to struct
• Make nil Version represent "send tasks away from versioned workers and to unversioned workers"

Why?

• To prevent misconfiguration and to expand the override definition to accommodate the new PinnedUntilContinueAsNew behaviors.
• Using a string to represent structured data, whose subfields frequently need to be considered separately, is brittle and not good for anyone using it. Struct is better.
• "unversioned version" is contradictory, and nil is a nice way to represent that the versioning story of a task queue is no longer in the control of the Deployment whose RoutingConfig you are reading.

Variables are being deprecated, but the content of the code is not changing.
The idea of "Unset Ramp" having a separate meaning from "0% Ramp" is removed. 0% ramp now is the only way to have "no ramp" / 100% of traffic going to Current Version. Nil ramping_deployment_version + non-zero ramping_version_percentage is the way to ramp traffic to unversioned workers.

The SDK interface for this could look like:

deployment := client.GetHandle(deploymentName)

// set current to a version
deployment.SetCurrentVersion(buildId) -> current set to deploymentName/buildId
deployment.UnsetCurrentVersion() -> current set to nil

// set current to unversioned
deployment.UnsetCurrentVersion() -> current set to nil


deployment.SetRampingVersion(buildId, 50) -> ramp set to (deploymentName/buildId, 50)
deployment.UnsetRampingVersion() -> ramp set to (nil, 0%)
deployment.RampToUnversioned(50) -> set to (nil, 50%)

Server PR

[Sushisource]

Nice! Much safer. Having all these deprecated fields is slightly sad, but, that's life. Let's make sure we track actually removing them after things are GA

None of my comments are blocking.

[Sushisource]

This one is gonna be supported (as part of the first change using this API), right?

[carlydf]

My plan was to only support the default UNSPECIFIED behavior in this first change, which means

// If original behavior is Pinned or PinnedUntilContinueAsNew, keep that behavior.
// If original behavior is AutoUpgrade, override behavior to Pinned.

because I felt that that maps best to what we currently have (in the world without 2 different types of pinned).

but arguably, // Override workflow behavior to be Pinned. (in the new world) is more equivalent to "pinned override" in the old world..

I'm fine with either, but "old-world pinned override" should default to exactly one of these three types

[cretz]

LGTM from a pure structural POV, but will want to wait for @Sushisource approval. It is unfortunate to have so many versioning deprecations overall on the API, I wonder if there are preventative things we can do in the future on other projects.

[Sushisource]

Great, happy with this and 10x more obvious than the previous iteration

[carlydf]

@ShahabT There is no more versioning info in the ActivityTaskStartedEvent, since we deprecated the version stamp and didn't replace it with anything.

We can ask the worker that is calling ActivityTaskCompleted to send a deployment options, and then turn that into a version, or we could do nothing. AFAIK, we store in the workflow execution info . versioning info the version that completed the last workflow task, but we do not store the version that completed the last activity task. So I forget how we handle versioning of activities, or if we even need to know what worker completed the activity task. But either way the comment "Use the info inside the corresponding ActivityTaskStartedEvent" needs to be corrected.

[carlydf]

There is a last_deployment_version in PendingActivityInfo

    // The Worker Deployment Version this activity was dispatched to most recently.
    // If nil, the activity has not yet been dispatched or was last dispatched to an unversioned worker.
    temporal.api.deployment.v1.WorkerDeploymentVersion last_deployment_version = 24;

I'm not yet sure when it's populated or what it's used for

[carlydf]

same comment as above, ActivityTaskStartedEvent has no version stamp now

[carlydf]

same comment as above, ActivityTaskStartedEvent has no version stamp now