proxy: v2.215.0

[olix0r]

This change culminates recent work to restructure the balancer to use a PoolQueue so that balancer changes may occur independently of request processing. This replaces independent discovery buffering so that the balancer task is responsible for polling discovery streams without independent buffering. Requests are buffered and processed as soon as the pool has available backends. Fail-fast circuit breaking is enforced on the balancer's queue so that requests can't get stuck in a queue indefinitely.

In general, the new balancer is instrumented directly with metrics, and the relevant metric name prefix and labelset is provided by the stack. In addition to detailed queue metrics including request (in-queue) latency histograms, but also failfast states, discovery updates counts, and balancer endpoint pool sizes.

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• outbound: Move queues into the concrete stack (outbound: Move queues into the backend stacks linkerd2-proxy#2539)
• metrics: Remove unused features (metrics: Remove unused features linkerd2-proxy#2542)
• Add the PoolQueue middleware (Add the PoolQueue middleware linkerd2-proxy#2540)
• ci: Fixup codecov config (ci: Fixup codecov config linkerd2-proxy#2545)
• ci: Cancel prior runs (ci: Cancel prior runs linkerd2-proxy#2546)
• ci: Skip ARM builds during non-release CI (ci: Skip ARM builds during non-release CI linkerd2-proxy#2547)
• deps: Update tokio, tonic, and prost (deps: Update tokio, tonic, and prost linkerd2-proxy#2544)
• build(deps): bump tj-actions/changed-files from 40.2.0 to 40.2.1 (build(deps): bump tj-actions/changed-files from 40.2.0 to 40.2.1 linkerd2-proxy#2549)
• metrics: Use prometheus-client for proxy_build_info (metrics: Use prometheus-client for proxy_build_info linkerd2-proxy#2551)
• balance: Add a p2c Pool implementation (balance: Add a p2c Pool implementation linkerd2-proxy#2541)
• metrics: Export process metrics using prometheus-client (metrics: Export process metrics using prometheus-client linkerd2-proxy#2552)
• linkerd_identity: split linkerd_identity::Id into DNS and URI variants (linkerd_identity: split linkerd_identity::Id into DNS and URI variants linkerd2-proxy#2538)
• outbound: Move HTTP balancer into its own module (outbound: Move HTTP balancer into its own module linkerd2-proxy#2554)
• app: Setup prom registry for use in balancers (app: Setup prom registry for use in balancers linkerd2-proxy#2555)
• vscode: Move workspace settings to devcontainer (vscode: Move workspace settings to devcontainer linkerd2-proxy#2557)
• build(deps): bump tj-actions/changed-files from 40.2.1 to 40.2.2 (build(deps): bump tj-actions/changed-files from 40.2.1 to 40.2.2 linkerd2-proxy#2556)
• balance: Instrument metrics in pool balancer (balance: Instrument metrics in pool balancer linkerd2-proxy#2558)
• Enable PoolQueue balancer (Enable PoolQueue balancer linkerd2-proxy#2559)