render-scaling

# Render Scaling This skill covers how to scale **Web Services**, **Private Services**, and **Background Workers** on Render: manual instance counts, **Professional+** autoscaling, plan (instance type) choices, and platform limits. Deeper tables and tuning guidance live under `references/`. ## When to Use - Setting or changing **instance count** (Dashboard, CLI, API, or Blueprint) - Configuring **autoscaling** (min/max, CPU and memory targets) - Choosing **vertical** (plan) vs **horizontal** (more instances) scaling - Understanding **constraints** (disks, static sites, cron/workflows, 100-instance cap) - **Cost** implications of multi-instance and per-second billing - **Blueprint** fields: `numInstances`, `scaling`, `plan` ## Manual Scaling - Set **instance count** from **1 to 100** via the **Dashboard**, **CLI**, or **API**. - **All instances share the same instance type** (plan); you cannot mix plans on one service. - Changes apply **immediately**: Render **provisions** new instances and **deprovisions** excess capacity as needed. ## Autoscaling - Available on **Professional and higher** workspaces only. - Configure **minimum** and **maximum** instances and targets for **CPU** and/or **memory** utilization (**1–90%** each). - **At least one metric must be enabled** (CPU or memory). If **both** CPU and memory autoscaling toggles are **off**, autoscaling is **disabled**. - If **both** manual instance settings and autoscaling are configured, **autoscaling wins**—manual count does not override the scaling policy in effect. ## Autoscaling Formula Render computes a candidate instance count from utilization vs target: `new_instances = ceil(current_instances * (current_utilization / target_utilization))` - When **both** CPU and memory targets are set, the platform uses the **larger** of the two `new_instances` values (the more conservative scale-out). ## Scaling Constraints | Constraint | Behavior | |------------|----------| | **Per service** | **Maximum 100** instances | | **Persistent disk** | **Cannot** scale to multiple instances—**single instance only** | | **Static sites** | **Not** scalable (served by CDN) | | **Cron jobs & Workflows** | Scaling model **does not apply** (different execution model) | ## Scale-Down Behavior - **Scale-up** is **immediate** when utilization supports it. - **Scale-down** waits **a few minutes** after conditions allow reduction (**spike protection**). This reduces **flapping** from brief load spikes. ## Instance Types - In Blueprints, the instance type is the **`plan`** field (e.g. `standard`, `pro`). - Options span **free** / **starter** through **standard**, **pro**, **pro_plus**, **pro_max**, **pro_ultra**—each with defined **CPU** and **RAM** (see `references/instance-types.md`). ### Vertical vs Horizontal | Need | Approach | When | |------|----------|------| | More throughput | **Horizontal** (add instances) | Stateless services, request-based workloads | | More RAM/CPU per process | **Vertical** (upgrade **plan**) | Memory-intensive or single-threaded apps | | Both | **Combine** | Right-size plan, then scale out for traffic | ## Cost Patterns - **Per-second billing**; **no separate fee** for scaling actions. - You pay roughly for **compute time × number of running instances** (see [Render pricing](https://render.com/pricing) for current rates). - **Right-size** by monitoring **CPU and memory** utilization (see **render-monitor**). ## Blueprint Configuration **Manual instance count:** ```yaml numInstances: 3 ``` **Autoscaling:** ```yaml scaling: minInstances: 1 maxInstances: 10 targetCPUPercent: 70 targetMemoryPercent: 80 ``` **Instance type (plan):** ```yaml plan: standard ``` Do not rely on `numInstances` to cap autoscaling when a `scaling` block is present—**autoscaling takes precedence**. Preview behavior for scaling is detailed in `references/autoscaling-guide.md`. ## References | Topic | File | |--------|------| | Plan names, CPU/RAM, flexible vs non-flexible, free tier | `references/instance-types.md` | | Enabling autoscaling, targets, min/max, mistakes, previews | `references/autoscaling-guide.md` | ## Related Skills - **render-web-services** — Web Service settings, disks, deploy lifecycle - **render-background-workers** — Worker-specific configuration and scaling context - **render-blueprints** — Full Blueprint schema and field reference - **render-monitor** — Metrics, logs, and utilization for right-sizing