kubevela/examples/legacy-upgrade-demo

Legacy CUE Upgrade Demo

A self-contained example that exercises all three CUE compatibility upgrade rules introduced in KubeVela v1.11. Each definition deliberately uses a pattern that breaks on CUE v0.14+ and is fixed transparently at render time by the upgrade engine.

The three issues

File	Rule	Broken pattern	Fixed pattern
component-db-provisioner.cue	list-arithmetic	list1 + list2, list * n	list.Concat([...]), list.Repeat(...)
trait-sidecar-logger.cue	error-field-label	error: "..." (unquoted)	"error": "..."
workflow-check-global-replica.cue	bool-default-negation	_flag: bool | *false + if-guard	direct boolean expression

Issue 1 — list arithmetic (component-db-provisioner.cue)

Pre-v1.11 definitions commonly use + to append env vars or init scripts:

allEnv: parameter.env + [{name: "MANAGED_BY", value: "kubevela"}]
expandedScripts: parameter.initScripts * parameter.scriptReplicas

CUE v0.14 made these a hard error. The engine rewrites them to:

allEnv: list.Concat([parameter.env, [{name: "MANAGED_BY", value: "kubevela"}]])
expandedScripts: list.Repeat(parameter.initScripts, parameter.scriptReplicas)

Issue 2 — error field label (trait-sidecar-logger.cue)

CUE v0.14 introduced error as a built-in function, breaking any field named error:

// parse error in CUE v0.14+
error: "unsupported log format; expected json or logfmt"

The engine quotes the field label:

"error": "unsupported log format; expected json or logfmt"

Issue 3 — bool default negation (workflow-check-global-replica.cue)

CUE v0.14 reads the default value of a bool | *false field before unification, so if !_isSecondary fires even when _isSecondary was set to true by a conditional block. This causes secondary clusters to incorrectly fail the engineVersion requirement:

// Broken: default evaluated before unification in CUE v0.14+
_isSecondary: bool | *false
if parameter.globalCluster != _|_ {
    if parameter.globalCluster.mode == "secondary" {
        _isSecondary: true
    }
}
if !_isSecondary {
    if parameter.engineVersion == _|_ {
        _engineVersionRequired: 0 & "engineVersion is required for primary clusters"
    }
}

The engine inlines the conditions directly into the flag value:

_isSecondary: (parameter.globalCluster != _|_ && parameter.globalCluster.mode == "secondary")
if !_isSecondary {
    if parameter.engineVersion == _|_ {
        _engineVersionRequired: 0 & "engineVersion is required for primary clusters"
    }
}

The Application

application.yaml deploys a secondary database replica that exercises all three definitions simultaneously:

• Component db-provisioner — Deployment with env var concatenation and init script repetition
• Trait sidecar-logger — injects a Fluent Bit sidecar and emits a status ConfigMap with an error field
• Workflow step check-global-replica — validates replica role; engineVersion is intentionally omitted to prove the bool-default-negation fix works (a secondary must not require it)

Usage

# 1. Apply the three definitions
vela def apply examples/legacy-upgrade-demo/component-db-provisioner.cue
vela def apply examples/legacy-upgrade-demo/trait-sidecar-logger.cue
vela def apply examples/legacy-upgrade-demo/workflow-check-global-replica.cue

# 2. Deploy the application
kubectl apply -f examples/legacy-upgrade-demo/application.yaml

# 3. Watch it reconcile — all three definitions are upgraded transparently
kubectl get application db-global-secondary -w

# 4. Confirm the workflow step result ConfigMap was created
kubectl get configmap replica-check-result -o yaml
# Expected: data.isSecondary=true, no engineVersion key

# 5. To see the raw failures, restart the controller with the flag disabled:
#      --enable-cue-version-compatibility=false
#    All three definitions will produce CUE compilation errors.

Upgrading definitions permanently

To fix the definitions at source rather than relying on the runtime compatibility layer:

vela def upgrade examples/legacy-upgrade-demo/component-db-provisioner.cue
vela def upgrade examples/legacy-upgrade-demo/trait-sidecar-logger.cue
vela def upgrade examples/legacy-upgrade-demo/workflow-check-global-replica.cue