This analysis is based on official pricing documentation and straightforward cost calculations.
TL;DR
- Pricing: Cloud Run is dramatically cheaper for short-running workloads (up to 17x cost difference)
- AWS Integration: App Runner provides native ecosystem integration worth considering
- Scaling: Cloud Run offers true scale-to-zero; App Runner keeps memory always-on
- Break-even point: ~20 hours/day runtime
The Price Differential Nobody Talks About
When evaluating serverless container platforms, most discussions focus on features. Let's focus on what actually matters: cost and architectural trade-offs.
Running 1 vCPU + 2GB memory in the Asia region:
| Daily Runtime | Cloud Run | App Runner | Difference |
|---|---|---|---|
| 2 hours | $1.04 | $17.82 | 17.1x |
| 4 hours | $7.31 | $22.68 | 3.1x |
| 8 hours | $24.62 | $32.40 | 1.3x |
| 12 hours | $39.93 | $42.12 | 1.05x |
| 24 hours | $85.07 | $71.28 | App Runner wins |
The cost reversal happens around 20 hours/day of continuous operation.
Architectural Differences That Drive Pricing
Cloud Run: True Serverless
Built on Knative with request-driven scaling:
Cost Model:
- vCPU: $0.000024/vCPU-second
- Memory: $0.0000025/GiB-second
- Billing granularity: per-second
- Free tier: 180,000 vCPU-sec, 360,000 GiB-sec monthly
Scale-to-zero: When idle, you pay nothing. This is the key differentiator.
App Runner: Hybrid Provisioning
Memory-always-on + CPU-on-demand model:
Cost Model:
- Provisioned (Memory): $0.009/GB-hour (always charged)
- Active (CPU): $0.081/vCPU-hour (only during processing)
Always-on memory: Base cost of $12.96/month for 2GB, regardless of usage.
The Math
Cloud Run: 2 Hours Daily Operation
Monthly runtime: 2h × 30d = 60h = 216,000 seconds
Resource consumption:
- vCPU: 1 vCPU × 216,000s = 216,000 vCPU-sec
- Memory: 2 GiB × 216,000s = 432,000 GiB-sec
After free tier:
- vCPU billable: 216,000 - 180,000 = 36,000 vCPU-sec
- Memory billable: 432,000 - 360,000 = 72,000 GiB-sec
Charges:
- vCPU: 36,000 × $0.000024 = $0.864
- Memory: 72,000 × $0.0000025 = $0.180
Total: $1.044
App Runner: 2 Hours Daily Operation
Fixed memory cost (always-on):
2GB × $0.009/GB-hour × 24h × 30d = $12.96
CPU cost (usage-based):
Monthly CPU runtime: 2h × 30d = 60h
1 vCPU × 60h × $0.081/vCPU-hour = $4.86
Total: $12.96 + $4.86 = $17.82
The $12.96 fixed cost is the critical factor. You're paying for memory reservation whether you use it or not.
When app runner makes sense
1. AWS ecosystem lock-in strategy
If you're running:
- RDS databases
- ElastiCache clusters
- S3 storage
- VPC-internal services
Example configuration:
services:
api:
image: your-app:latest
environment:
DATABASE_URL: postgresql://rds-endpoint
S3_BUCKET: your-bucket
instance_role: arn:aws:iam::account:role/AppRunnerRole
IAM-based authentication eliminates credential management overhead. VPC connector provides direct private subnet access.
2. VPC Integration requirements
App Runner → VPC Connector → Private Subnet → RDS
vs
Cloud Run → Internet → Cloud SQL Proxy → Cloud SQL
App Runner's VPC integration is simpler for private resource access.
3. Predictable performance requirements
No cold starts. Memory is always provisioned. Response time predictability matters for SLA-driven services.
4. 24-Hour operation
At 24/7 runtime, App Runner is actually cheaper ($71.28 vs $85.07).
5. Operational consolidation
Single cloud provider strategy reduces:
- Multi-cloud operational overhead
- Cross-cloud networking complexity
- Team training requirements
- Security policy fragmentation
6. Simplified auto-scaling
# App Runner
auto_scaling_configuration:
max_concurrency: 100
max_size: 10
min_size: 1
vs
# Cloud Run (more verbose)
spec:
template:
metadata:
annotations:
autoscaling.knative.dev/maxScale: "10"
autoscaling.knative.dev/minScale: "0"
run.googleapis.com/cpu-throttling: "false"
When Cloud Run is the Clear Winner
1. Cost-Constrained Projects
Early-stage startups, MVPs, personal projects. $1.04/month vs $17.82/month is a 17x difference that compounds across multiple services.
2. Irregular/Low-Frequency Traffic
- Batch jobs (few daily executions)
- Webhook endpoints
- Development/staging environments
- Demo applications
True scale-to-zero means zero cost during idle periods.
3. Google Cloud Native Integration
Native integration with:
- Firebase
- BigQuery
- Google Workspace APIs
- Cloud Storage
4. Geographic distribution
Cloud Run supports more regions for global deployment.
Cold start reality check
Cold start times vary significantly by runtime and application design.
Based on typical container startup patterns:
- Lightweight Node.js: 500ms-1s
- Heavy JVM applications: 3-5s
- Minimum instance configuration can mitigate this
App Runner's always-on memory eliminates cold starts entirely.
Migration path considerations
Cloud Run → GKE: Relatively straightforward due to Knative foundation.
App Runner → EKS: Requires more significant architectural changes.
If Kubernetes migration is in your roadmap, Cloud Run provides a smoother path.
Decision framework
Choose Cloud Run if:
- Runtime < 12 hours/day
- Cost is primary constraint
- Traffic is sporadic/unpredictable
- Google Cloud ecosystem alignment
Choose App Runner if:
- Runtime > 20 hours/day
- AWS ecosystem consolidation
- VPC integration critical
- Cold start sensitivity
- Predictable performance required
The uncomfortable truth
Cloud Run's pricing advantage is undeniable for short-running workloads. The 17x cost difference at low utilization is architectural, not operational.
However, infrastructure decisions require considering:
- Long-term operational complexity costs
- Team expertise and training overhead
- Integration friction across cloud boundaries
- Compliance and security policy alignment
For AWS-committed organizations, paying 3x more might be strategically rational when factoring in operational efficiency.
For new projects with flexible infrastructure choices, Cloud Run's economics are compelling.
What I Don't Know
These require real-world usage data:
- Long-term pricing stability (both vendors adjust pricing)
- Network egress costs at scale
- Support response quality differences
- Enterprise discount negotiation leverage
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