gh-netresearch-claude-code-marketplace-netresearch-skills-bundle/skills/typo3-ddev/references/0001-valkey-default-with-redis-alternative.md

ADR 0001: Default to Valkey with Redis Alternative

Status: Accepted

Date: 2025-10-22

Decision Makers: TYPO3 DDEV Skill Maintainers

Tags: #caching #infrastructure #licensing #future-proofing

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Context

The Redis Licensing Change (March 2024)

Redis changed its license from BSD-3-Clause (open source) to a dual RSALv2/SSPLv1 license, which is NOT OSI-approved open source. This change:

• Restricts commercial use of Redis as a managed service
• Creates legal compliance concerns for cloud providers and hosting companies
• Prevents offering Redis-as-a-service without Redis Ltd licensing agreements

The Valkey Fork (March 2024)

In response, the Linux Foundation launched Valkey, a fork of Redis 7.2.4, with backing from:

• Amazon Web Services (AWS)
• Google Cloud
• Oracle Cloud
• Ericsson
• Snap Inc.
• 40+ additional companies

Valkey maintains BSD-3-Clause licensing (true open source) and wire-protocol compatibility with Redis.

Cloud Provider Adoption

AWS ElastiCache (October 2024):

• Added Valkey 7.2 support
• Added Valkey 8.0 support (November 2024)
• Pricing: 20% lower for node-based, 33% lower for serverless vs Redis
• Performance: Claims 230% higher throughput, 70% better latency (Valkey 8.0 vs 7.2)

Industry Trajectory:

• AWS MemoryDB supports Valkey
• Google Cloud and Oracle are Valkey project sponsors
• Economic pressure (20-33% cost savings) will drive hosting provider migration

TYPO3 Caching Requirements

TYPO3's Redis cache backend uses basic operations:

• GET, SET, DEL, EXPIRE - Key-value operations
• FLUSHDB - Cache clearing
• KEYS pattern matching - Cache inspection

These operations are identical in Redis and Valkey (wire-protocol compatible). TYPO3 does not use advanced Redis features (Streams, JSON, Search, etc.).

DDEV Development Environment Context

The TYPO3 DDEV Skill provides a reference implementation for local development environments. Developers using this skill:

• Test TYPO3 extensions locally before production deployment
• Do not control production infrastructure (clients/hosting providers do)
• Need development environments that match future production reality
• Benefit from faster Docker image pulls (smaller images = faster ddev start)

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Decision

Default to Valkey 8-alpine for new TYPO3 DDEV projects, with Redis 7-alpine as a documented alternative.

Implementation Details

Default Configuration

# .ddev/docker-compose.services.yaml (new projects)
services:
  valkey:
    container_name: ddev-${DDEV_SITENAME}-valkey
    image: valkey/valkey:8-alpine
    restart: unless-stopped
    ports:
      - "6379"
    volumes:
      - valkey-data:/data
    environment:
      - VALKEY_MAXMEMORY=256mb
      - VALKEY_MAXMEMORY_POLICY=allkeys-lru
    command: valkey-server --appendonly yes --maxmemory 256mb --maxmemory-policy allkeys-lru

volumes:
  valkey-data:
    name: "${DDEV_SITENAME}-valkey-data"

Alternative: Redis 7-alpine

# Alternative for legacy production parity
services:
  redis:
    container_name: ddev-${DDEV_SITENAME}-redis
    image: redis:7-alpine
    # ... same configuration structure

Auto-Detection Logic

For existing projects with .ddev/docker-compose.services.yaml:

• Preserve existing choice: If Redis is detected, keep Redis
• Preserve existing choice: If Valkey is detected, keep Valkey
• Inform user: Log which cache service was detected and preserved

For new projects:

• Default to Valkey 8-alpine
• Document Redis alternative: Show how to switch in generated README
• Provide rationale: Explain why Valkey is the forward-looking choice

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Consequences

Positive

✅ Future-Proof Development Environments

• Matches the production trajectory (AWS/Google/Oracle adoption)
• Prepares developers for 2025-2027 hosting landscape
• Reduces future migration friction when hosting providers switch

✅ Cost Awareness

• Educates developers about cost-effective infrastructure choices
• Aligns with hosting provider economic incentives (20-33% savings)
• Demonstrates modern cloud architecture patterns

✅ True Open Source

• BSD-3-Clause license with no commercial restrictions
• No legal compliance concerns for hosting providers
• Community-driven governance (Linux Foundation)

✅ Smaller Docker Images

• Valkey 8-alpine: 69.7 MB
• Redis 8-alpine: 100 MB (30% larger)
• Redis 7-alpine: 60.6 MB
• Faster ddev start cycles during development

✅ Drop-In Compatibility

• Wire-protocol identical to Redis
• TYPO3's PHP redis extension works without modification
• Zero code changes required for TYPO3 extensions
• Easy rollback to Redis if needed (one-line change)

Negative

⚠️ Newer Codebase

• Valkey fork is only 1 year old (since March 2024)
• Less Stack Overflow content compared to Redis
• Potential for undiscovered edge-case bugs

Mitigation:

• Based on Redis 7.2.4 (stable, battle-tested codebase)
• AWS/Google/Oracle using in production validates stability
• DDEV makes switching back to Redis trivial (one-line change)
• Redis documentation applies due to protocol compatibility

⚠️ Learning Curve

• Developers familiar with "Redis" terminology need to learn "Valkey"
• Some confusion about naming/branding

Mitigation:

• Comprehensive ADR and documentation explains context
• Clear instructions for both Valkey and Redis alternatives
• Educational opportunity to teach open source licensing issues

⚠️ Current Production Mismatch

• Some existing TYPO3 hosting environments still use Redis 7.x
• Development-production parity temporarily impacted

Mitigation:

• Redis 7-alpine documented as alternative for production parity
• Auto-detection preserves existing Redis choice in projects
• Easy to switch (one-line change in docker-compose)
• Trade-off: Match today's production vs prepare for tomorrow's

Risks and Mitigations

Risk	Severity	Likelihood	Mitigation
Valkey compatibility issues with TYPO3	Low	Very Low	Wire-protocol identical, PHP redis extension works transparently
Valkey bugs in production use	Medium	Low	AWS/Google production usage validates stability; easy rollback
Developer confusion/resistance	Low	Medium	Clear documentation, explain rationale, provide Redis alternative
Community backlash for being "too progressive"	Low	Low	Document decision thoroughly, auto-preserve existing choices

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Alternatives Considered

Alternative 1: Redis 7-alpine Default (Conservative)

Reasoning:

• Most existing TYPO3 hosting uses Redis 7.x
• Maximum development-production parity today
• Battle-tested, 15 years of production use
• Familiar to developers

Rejected Because:

• Optimizes for yesterday's production, not tomorrow's
• Ignores industry trajectory (AWS/Google/Oracle Valkey adoption)
• Creates educational debt (developers learn old patterns)
• Proprietary licensing creates compliance concerns
• Misses opportunity to lead the transition

Alternative 2: Redis 8-alpine Default

Reasoning:

• Latest Redis version
• Performance improvements over Redis 7

Rejected Because:

• Proprietary licensing (same as Redis 7.4+)
• Larger image size (100 MB vs 69.7 MB Valkey)
• More expensive on cloud providers vs Valkey
• Not the strategic direction of major cloud platforms

Alternative 3: No Caching Service by Default

Reasoning:

• Simpler default setup
• Developers add only if needed

Rejected Because:

• Redis/Valkey caching is common in TYPO3 production
• Reference implementation should include production-realistic services
• DDEV skill aims to provide complete development environment
• Adding later is more friction than having it by default

Alternative 4: Offer Both Redis and Valkey as Equal Choices

Reasoning:

• Maximum flexibility
• No opinionated defaults

Rejected Because:

• Adds complexity to setup process
• Forces developers to make decision without context
• Reference implementations should have opinionated best practices
• Still need to pick ONE as default for generation
• Documentation burden increases (maintain two equal paths)

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References

Technical Documentation

• Valkey Official Site
• Valkey GitHub Repository
• AWS ElastiCache for Valkey Announcement
• TYPO3 Redis Cache Backend Documentation

Benchmarks and Analysis

• AWS ElastiCache Valkey 8.0: 230% throughput improvement, 70% latency improvement vs Valkey 7.2
• AWS Cost Comparison: Valkey 20% cheaper (node-based), 33% cheaper (serverless) vs Redis
• Docker Image Sizes:
  • valkey/valkey:8-alpine - 69.7 MB
  • redis:8-alpine - 100 MB
  • redis:7-alpine - 60.6 MB

Licensing

• Redis License Change: Redis Announcement (March 2024)
• Valkey License: BSD-3-Clause (OSI-approved open source)
• Linux Foundation Valkey Announcement: TechCrunch Article

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Decision Rationale Summary

This decision is strategic and forward-looking rather than purely technical:

1. Technical Equivalence: For TYPO3 use cases, Redis and Valkey are functionally identical
2. Strategic Positioning: Major cloud providers (AWS, Google, Oracle) are adopting Valkey
3. Economic Reality: 20-33% cost savings will drive hosting provider migration
4. Licensing Safety: True open source (BSD-3) vs proprietary licensing concerns
5. Educational Leadership: Skill should teach future patterns, not legacy patterns
6. Risk Mitigation: Easy rollback, auto-preservation of existing choices, clear documentation

The default to Valkey is a bet on the industry trajectory being correct, backed by Linux Foundation + AWS + Google + Oracle. The risk is minimal (easy rollback), and the educational benefit is high (teaching developers about open source licensing, cost-effective infrastructure, and future-proof choices).

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Valkey 9.0 Consideration (October 2025)

Release Information:

• Valkey 9.0 GA: Released October 21, 2025
• Status: Stable production release
• Docker Image: valkey/valkey:9-alpine available

Performance Improvements

Throughput:

• 40% higher throughput compared to Valkey 8.1
• Supports over 1 billion requests per second in cluster configurations
• Memory prefetching for pipelined commands
• Zero-copy responses for large requests
• SIMD optimizations (up to 200% faster BITCOUNT, hyperloglog)
• Multipath TCP support (up to 25% lower latency)

Major New Features

Hash Field Expiration:

• TTL on individual fields within a hash
• Automatic expired data removal
• Improved memory efficiency

Atomic Slot Migration:

• Snapshot-based migration for horizontal scaling
• Zero-downtime scaling
• Source and target nodes remain active during transfer

Multiple Databases in Cluster Mode:

• Multiple logical namespaces on single cluster
• Better keyspace organization
• Reduced memory waste

Production Adoption Status

Cloud Provider Support (as of October 2025):

• ❌ AWS ElastiCache: Not yet supported (latest: Valkey 8.1 - July 2025)
• ❌ Google Cloud: No announcement
• ❌ Oracle Cloud: No announcement

Docker Hub:

• ✅ Official images available: valkey/valkey:9.0-alpine
• ✅ Wire-protocol compatible with Valkey 8.x and Redis 7.x

Decision: Stay with Valkey 8 for Now

Rationale:

This differs from the original Valkey vs Redis decision:

• Valkey vs Redis (Original): Industry was MIGRATING → Lead with Valkey 8
• Valkey 8 vs 9 (Now): Industry STABLE on 8 → Follow production

Why wait for Valkey 9:

1. Production Parity: AWS ElastiCache only supports up to Valkey 8.1
2. Very New: Released October 21, 2025 (1 day old at time of writing)
3. Hosting Adoption: No TYPO3 hosting providers using Valkey 9 yet
4. Upgrade Urgency: GitHub release notes state "LOW" urgency
5. Battle-Testing: Valkey 8.x more production-proven

Benefits of Staying on Valkey 8:

• ✅ Cloud provider support (AWS ElastiCache available)
• ✅ Production-aligned (matches hosting environments)
• ✅ Battle-tested (in production since November 2024)
• ✅ Conservative approach (let others find bugs first)

When to Upgrade to Valkey 9:

Monitor for these signals:

1. AWS ElastiCache announces Valkey 9 support
2. 3+ months of production stability reports
3. Major TYPO3 hosting providers adopt Valkey 9
4. Performance improvements become critical for use case

Upgrade Path

Seamless Migration (when ready):

Valkey 8 → 9 upgrade is simple (wire-compatible):

# Change from:
image: valkey/valkey:8-alpine

# To:
image: valkey/valkey:9-alpine

No configuration changes required. No data migration needed. Restart container.

Trade-offs:

• Wait: Production parity, battle-tested, conservative (recommended)
• Upgrade Now: 40% faster, cutting-edge, slightly risky

Recommendation: Wait for AWS ElastiCache support before defaulting to Valkey 9 in skill templates.

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Review and Updates

Next Review Date: 2026-04-01 (6 months from October 2025)

Trigger for Re-evaluation:

• Major TYPO3 hosting providers publicly announce Redis-only support policies
• Valkey compatibility issues discovered affecting TYPO3
• Valkey project loses major sponsor backing
• Cloud provider pricing changes making Redis competitive again

Success Metrics:

• Developer feedback on Valkey default (GitHub issues, discussions)
• Number of projects switching from Valkey to Redis (indicates friction)
• Hosting provider announcements about Valkey adoption
• TYPO3 community discussion about cache backends

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Approved By: TYPO3 DDEV Skill Project

Implementation: v2.0.0 (target release)