feat(nodejs): gRPC TLS/DNS failover, 12 runtime meters, Java agent.core alignment

[songzhendong]

Summary

This PR extends the Node.js agent remote layer to align with the Java agent.core gRPC architecture, and expands runtime metrics from 6 to 12 instance_nodejs_* meters.

1. gRPC v2 — GRPCChannelManager multi-backend failover, TLS/mTLS, per-hostname SNI, DNS expand (A/AAAA), optional periodic DNS re-resolve, IPv6 formatHostPort, CommandService ingestion.
2. Runtime metrics — six additional meters (array_buffers, uptime, peak_malloced_memory, detached_contexts, old_space_used, new_space_used); canonical env SW_AGENT_RUNTIME_METRICS_* with legacy aliases retained.

Not in this PR: OAP MAL rules / dashboards (separate PR required), release version bump, Profile/Log/Event clients, full Command executor registration.

Motivation

• Cross-language parity: Java agent already uses GRPCChannelManager, TLS, DNS expansion, and periodic re-resolve; Node previously lacked equivalent failover and TLS/SNI behavior (notably Kubernetes Headless Service → Pod IP with cert hostname mismatch).
• Maintainability: v1 refactor introduced agent.core layout; v2 completes remote connectivity features on that foundation.

OAP companion (required for 12-meter dashboards)

Meter reporting is in this PR. OAP consumption (MAL analyzer + dashboard docs + e2e-v2 TLS/DNS/auth cases) is a separate PR to apache/skywalking:

Item	Location
12 MAL rules	meter-analyzer-config/nodejs-runtime.yaml
Dashboard doc	docs/en/setup/backend/dashboards-nodejs-runtime.md
Node.js e2e (ssl / mtls / ssl-dns / auth)	test/e2e-v2/cases/nodejs/*
Agent pin	test/e2e-v2/script/env → SW_AGENT_NODEJS_COMMIT=7c7eba5

Companion OAP PR: songzhendong/skywalking #6.

Intentional differences from Java (please review)

Area	Java	This PR	Tag
Auth failure (UNAUTHENTICATED / PERMISSION_DENIED)	Treated as network error → reconnect	Log warn, no reconnect	Stricter ops behavior
mTLS paths set but PEM missing	Warn, continue one-way TLS	throw at channel build	Stricter
Meter burst on reconnect	No per-tick snapshot cap	SW_AGENT_RUNTIME_METRICS_MAX_SNAPSHOTS_PER_REPORT default 1	Tunable guard
Exported config to apps	Config.Agent.AUTHENTICATION readable	publicAgentConfig omits authorization	Node-only hardening

Operational constraints (DNS lookup blocking, runtime sampling on main thread, etc.): docs/nodejs-grpc-constraints.md.

Key env vars (new / renamed)

Variable	Purpose
SW_AGENT_IS_RESOLVE_DNS_PERIODICALLY	Periodic DNS re-resolve (Java collector.is_resolve_dns_periodically)
SW_AGENT_GRPC_CHANNEL_CHECK_INTERVAL	Channel health check interval (seconds)
SW_AGENT_FORCE_RECONNECTION_PERIOD	Force reconnect period multiplier
SW_AGENT_FORCE_TLS / SW_AGENT_SSL_*	TLS/mTLS material paths
SW_AGENT_COLLECTOR_GRPC_UPSTREAM_TIMEOUT	gRPC call deadline (seconds)
SW_AGENT_RUNTIME_METRICS_*	Runtime meter pipeline (replaces SW_AGENT_NODEJS_RUNTIME_METRICS_* as canonical)

Legacy SW_AGENT_NODEJS_RUNTIME_METRICS_*, SW_AGENT_NVM_* aliases still accepted with deprecation warnings.

Test plan

Agent CI (Actions run @ 7c7eba5):

• Build (Node 20 / 22 / 24)
• License
• Lint + TestLib
• TestUnitRemote (config / core / remote / runtime) × 20/22/24
• TestRemoteE2E (static-failover, dns-re-resolve) × 20/22/24
• TestPlugins matrix (express meterSize 12, axios, http, ioredis, mongodb, mysql, …)

OAP e2e-v2 (songzhendong/skywalking #6, pin 7c7eba5):

• Agent NodeJS Backend / Frontend / Frontend ES / Frontend ES Sharding
• Agent NodeJS SSL / SSL DNS / mTLS / Auth

Files of note

Path	Role
src/agent/core/remote/*	Channel manager, TLS, DNS resolver, clients
src/agent/core/commands/*	OAP command queue + dispatch framework
src/agent/core/meter/*	12 runtime meters
tests/remote-e2e/*	Docker-compose failover E2E (CI)
tests/remote/*	Unit tests for remote layer
docs/nodejs-grpc-constraints.md	Node/grpc-js operational notes