feat(tern): add static target router#339
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Pull request overview
This PR introduces a new data-plane routing seam for Tern by adding a targetresolver contract plus a tern.TargetRouter client that resolves opaque targets into connection inputs and caches per-target local clients. This is intended to let deployments start with static target configuration and later swap to dynamic/inventory-backed resolution without reimplementing lookup/caching.
Changes:
- Added
pkg/targetresolverwith aResolverinterface and a YAML-configurableStaticResolverbackend. - Added
pkg/tern/target_router.go, atern.Clientimplementation that resolves targets and routes operations through cachedLocalClients. - Added unit tests for both the target router and the static resolver.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| pkg/tern/target_router.go | Adds TargetRouter that resolves targets and routes/caches local clients, including observer handling. |
| pkg/tern/target_router_test.go | Adds unit tests validating basic routing/caching and observer attachment behavior. |
| pkg/targetresolver/resolver.go | Defines the resolver request/result contract for opaque target resolution. |
| pkg/targetresolver/static.go | Implements a static, YAML-backed resolver with secret expansion for DSNs. |
| pkg/targetresolver/static_test.go | Adds unit tests for static resolution, validation, and metadata cloning behavior. |
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| mu sync.Mutex | ||
| clientsByTarget map[string]Client | ||
| activeObservers map[int64]ProgressObserver | ||
| pendingObservers map[string]ProgressObserver | ||
| } |
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| func (r *TargetRouter) clientForStoredApply(ctx context.Context, apply *storage.Apply) (Client, error) { | ||
| if apply == nil { | ||
| return nil, fmt.Errorf("stored apply is required for target routing") | ||
| } | ||
| target := apply.GetOptions().Target | ||
| if target == "" { | ||
| target = apply.Database | ||
| } | ||
| return r.clientOnlyForTarget(ctx, target, apply.DatabaseType, apply.Environment) | ||
| } |
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| func TestTargetRouterRoutesStoredApplyByTargetOption(t *testing.T) { | ||
| resolver := newStaticTargetResolver(t) | ||
| created := make(map[string]*targetRouterRecordingClient) | ||
| apply := &storage.Apply{ | ||
| ID: 42, | ||
| ApplyIdentifier: "apply-42", | ||
| Database: "orders", | ||
| DatabaseType: storage.DatabaseTypeMySQL, | ||
| Environment: "production", | ||
| } | ||
| apply.SetOptions(storage.ApplyOptions{Target: "dsid-orders-prod"}) | ||
| store := targetRouterApplyStore{ | ||
| byID: map[int64]*storage.Apply{42: apply}, | ||
| byIdentifier: map[string]*storage.Apply{"apply-42": apply}, | ||
| } | ||
| router := newTargetRouterForTest(t, resolver, store, created) | ||
| router.SetObserver(42, targetRouterNoopObserver{}) | ||
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Co-authored-by: Amp <amp@ampcode.com> Amp-Thread-ID: https://ampcode.com/threads/T-019eb357-321a-7760-b4fe-e3c606cba251
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…-free targets Move MySQL schema selection out of target resolution and into LocalClient execution. A target DSN that already names a database keeps the local-DSN behavior, where the namespace is an organizational label and Spirit connects to the DSN's database. A namespace-free target DSN is the inventory/data-plane shape: the concrete namespace is the connection schema and is injected per Spirit operation at plan, pull, apply, stop, cutover, and resume. This lets the target router cache one namespace-free LocalClient per target while each schema change connects to its own namespace, and keeps the inventory contract free of execution namespaces. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
controlSetup feeds Volume and other control operations; resolve the task's namespace credentials so namespace-free MySQL targets connect to the right schema instead of the namespace-free target DSN. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This was referenced Jun 14, 2026
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Why
A data-plane process needs a reusable way to serve many opaque execution targets without each embedder rebuilding inventory lookup and per-target client caching.
What
tern.TargetRouter, atern.Clientthat resolves a target viapkg/inventoryand caches LocalClients keyed by target/type/environment (a data plane has one deployment and many targets).Risk
Low — additive and not wired into the default server path yet. Existing clients keep using the current routing unless a caller explicitly constructs the router.
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