Skip write warmup in read-only mode

[eazyhozy]

Summary

Fix read-only mode warmup: skip write operations at both HTTP and engine levels instead of blocking them with the filter.

Problem

When running with actionbase.read-only=true and warmup enabled, two write paths caused issues:

1. HTTP warmup (ServiceLabelEdgeControllerWarmUp): Sends POST/PUT/DELETE to /graph/v2/service/sys/label/info/edge on localhost — blocked by ReadOnlyRequestFilter
2. Engine warmup (Graph.warmUp): Performs fake edge writes to warm HBase connections — unnecessary write load on production HBase from read-only servers

Changes

• ServiceLabelEdgeControllerWarmUp: Use GET-only warmup methods when readOnly=true
• GraphConfig: Add readOnly: Boolean field
• GraphConfiguration: Pass serverProperties.readOnly to GraphConfig
• Graph.kt: Extend existing label.entity.readOnly check with || readOnly to skip engine-level write warmup
• StartUpTest: Add E2E test for read-only=true + warmup.enabled=true combination

How to Test

./gradlew :server:test --tests "com.kakao.actionbase.server.StartUp*"
./gradlew :server:test --tests "com.kakao.actionbase.server.filter.ReadOnlyRequestFilterTest"

[eazyhozy]

@em3s Could you review this?

This fixes a startup failure when actionbase.read-only=true. The warmup process (ServiceLabelEdgeControllerWarmUp) sends POST/PUT/DELETE to /graph/v2/service/sys/label/info/edge internally, but ReadOnlyRequestFilter was blocking them — causing readiness probe to fail.

The fix adds an exact-path exception for this single warmup endpoint.

Pod logs from a read-only deployment:

INFO  c.k.a.s.filter.ReadOnlyRequestFilter : ReadOnlyRequestFilter is active. Write operations on [/graph/v2, /graph/v3] will be rejected.
WARN  c.k.a.s.filter.ReadOnlyRequestFilter : Blocked write request in read-only mode: PUT /graph/v2/service/sys/label/info/edge
ErrorCallbackNotImplemented: WebClientResponseException$Forbidden: 403 Forbidden from PUT http://localhost:8080/graph/v2/service/sys/label/info/edge

[em3s]

Good workaround, but can we solve it differently? For example, enabling ReadOnlyRequestFilter only after the warmup?

[eazyhozy]

@em3s Thanks for the suggestion — agreed, activating the filter after warmup is a cleaner approach. I'll update the PR.

[eazyhozy]

Updated — the filter now starts inactive and is activated after warmup completes, instead of allowlisting a specific path.

Changes:

• ReadOnlyRequestFilter: starts inactive (AtomicBoolean), activate() enables blocking
• ServiceLabelEdgeControllerWarmUp: calls activate() after readiness UP
• WebFilterConfig: fallback ApplicationReadyEvent listener activates the filter when warmup is disabled
• Tests: added inactive/activated unit tests + E2E test for read-only + warmup combination

[eazyhozy]

Activation flow & safety:

Scenario	Filter state	K8s traffic	Risk
Warmup success → readiness UP → activate()	Active (blocking)	Routed to pod	None
Warmup failure → readiness DOWN	Inactive (pass-through)	Not routed (probe fails)	None — no external requests reach the filter

activate() is a single AtomicBoolean.compareAndSet — it cannot fail or throw. If readiness UP fails, activate() is never reached, but K8s won't route traffic to the pod anyway.

[eazyhozy]

@em3s Gentle reminder — updated per your feedback (filter activates after warmup instead of path allowlist).

[em3s]

How about just adding some condition to avoid writing? @eazyhozy .

actionbase/engine/src/main/kotlin/com/kakao/actionbase/v2/engine/Graph.kt

Line 689 in d0299f8

if (label.entity.readOnly) {

[eazyhozy]

@em3s Thanks for the suggestion — it led me to reconsider the approach.

Since read-only servers don't need write warmup, disabling warmup via kc.graph.warm-up.enabled=false avoids the conflict entirely with no code changes. Would this approach work? If so, I'll close this PR.

[eazyhozy]

@em3s Updated the PR based on your feedback.

Problem: When running with read-only: true, the HTTP-level write warmup (ServiceLabelEdgeControllerWarmUp) is blocked by ReadOnlyRequestFilter, causing startup errors.

Minimal fix in this PR:

• ServiceLabelEdgeControllerWarmUp: In read-only mode, warmup uses only GET requests (skips POST/PUT/DELETE)
• ReadOnlyRequestFilter: Removed activate() — the filter is active from startup since write warmup is no longer sent in read-only mode
• WebFilterConfig: Removed readOnlyFilterActivator bean

Regarding Graph.kt (engine layer):
Even in server read-only mode, the engine-level warmup (Graph.warmUp) will still perform fake edge writes to warm up HBase connections. This doesn't cause startup issues (it doesn't go through the HTTP filter), but to skip it we'd need to pass the readOnly property down to GraphConfig, which expands the scope of this PR. Should we handle this here or in a separate PR?

[em3s]

@eazyhozy

Pushed a commit based on my earlier suggestion — extending the if (label.entity.readOnly) condition in Graph.kt. Please review and update the PR description accordingly.

[eazyhozy]

@em3s Thanks for pushing the Graph.kt change — this covers the engine-level warmup I was unsure about scoping in. LGTM, updated the PR description to reflect the final approach.