[wylswz]

Summary

• With activation enabled, a long-running serverless invocation could be scaled to zero by the connector while it was still running. After the activation preflight succeeds, the daemon now calls POST /v1/activation/activate again on a fixed interval until the invocation finishes, which renews the plugin's activity lease.

• New env var DIFY_PLUGIN_SERVERLESS_CONNECTOR_ACTIVATION_KEEPALIVE_INTERVAL (seconds, default 60). It only applies when DIFY_PLUGIN_SERVERLESS_CONNECTOR_ACTIVATION_ENABLED=true. The connector idle time should be at least 2× this interval.

• Each keepalive call times out after one interval, so calls never overlap. Keepalive stops before the invocation ends, so no calls are made after the END message.

• A failed keepalive is logged with log.Warn and does not fail the invocation.

• Config validation now rejects a non-positive interval when activation is enabled. Docs (sri.md, sri_cn.md) and .env.example are updated.

• A panic inside the keepalive goroutine is caught and logged, so it cannot crash the daemon. This goroutine does not go through routine.Submit.

Test plan

• go build ./...
• go vet ./internal/core/serverless_runtime/... ./internal/types/app/...
• go test ./internal/core/serverless_runtime/... ./internal/types/app/... (new tests cover: repeated renewals during a long invocation, no calls after the invocation ends, a keepalive failure leaving the invocation intact, no calls when activation is disabled, a panic in the keepalive goroutine being recovered without crashing or hanging, and config validation)
• Manual check on a cluster with activation enabled: confirm a long-running invocation is not scaled down

Generated with Devin

[Copilot]

🟡 Changes recommended

Defaulting replaces an explicitly configured zero keepalive interval with 60 before validation, bypassing the non-positive interval check during startup, while the test misses this parsing/defaulting sequence.

1 open issue

• Explicit zero keepalive interval bypasses validation · New

What changed in this PR

This PR adds periodic activation requests to keep long-running serverless plugin invocations from being scaled to zero.

Changes:

• Adds a keepalive loop with cancellation, warning logs on failure, and panic recovery.
• Introduces a configurable keepalive interval, defaulting to 60 seconds, with validation.
• Adds lifecycle and configuration tests and updates English and Chinese documentation.

File	Description
internal/​types/​app/​default.go	Sets the default keepalive interval.
internal/​types/​app/​config.go	Adds the interval setting and validation.
internal/​types/​app/​config_test.go	Tests rejection of non-positive intervals.
internal/​core/​serverless_runtime/​type.go	Passes the configured interval into the runtime.
internal/​core/​serverless_runtime/​io.go	Starts and stops periodic activation during invocations.
internal/​core/​serverless_runtime/​io_test.go	Tests renewals, shutdown, failures, disabled activation, and panic recovery.
docs/​runtime/​sri.md	Documents keepalive configuration and behavior in English.
docs/​runtime/​sri_cn.md	Documents keepalive configuration and behavior in Chinese.
.env.example	Adds the keepalive environment variable and idle-time guidance.

_{Review effort: Balanced}

[zhangx1n]

LGTM