docs: list Postgres/Redis region availability per cloud

[defangdevs]

Summary

Fixes #423 — documents managed Postgres/Redis region availability per cloud, without hardcoding a region list that would go stale.

• AWS (docs/providers/aws.md): Amazon RDS and ElastiCache ship to every AWS Region launch — one-line note, no gap to document.
• GCP (docs/providers/gcp.md): Cloud SQL and Memorystore for Redis are available in essentially all GCP regions — one-line note with links to the region lists.
• Azure (docs/providers/azure.md): this is the actual gap. Azure Database for PostgreSQL and Azure Managed Redis roll out region-by-region, and Microsoft's own docs point to a live "Products available by region" page rather than a static list, since it changes as regions come online. Also called out: Defang auto-selects a specific VM SKU per tier, which can hit a regional capacity limit even in a region where the service itself is generally available.
• docs/concepts/managed-storage/managed-postgres.mdx and managed-redis.md: short pointer from the "Current Support" table to the new Azure section, instead of duplicating content across pages.

Why no static region table

Azure's own docs explicitly say availability is "continually expanding" and defer to a live, filterable page — a static markdown table here would be wrong within weeks. Linking to the authoritative source is more maintainable and avoids a documentation drift risk.

Test plan

• npm install + cloned sibling defang/samples repos + bash scripts/prebuild.sh + npx docusaurus build — build succeeds.
• Confirmed the new internal anchor link (/docs/providers/azure#managed-postgres-and-redis-region-availability) resolves — it does not appear in the build's "broken anchors" list (which only lists pre-existing unrelated ones).
• Diff reviewed; only the 5 intended files changed.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Added regional availability guidance for Managed Postgres and Managed Redis across AWS, Azure, and GCP.
  • Clarified that AWS and GCP regions are broadly supported, while Azure availability varies by region.
  • Added links to provider-specific availability resources for planning deployments.
  • Documented Azure capacity and VM SKU errors, including guidance to try another region when necessary.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between ac3d9c7 and be7046e.

📒 Files selected for processing (5)

• docs/concepts/managed-storage/managed-postgres.mdx
• docs/concepts/managed-storage/managed-redis.md
• docs/providers/aws.md
• docs/providers/azure.md
• docs/providers/gcp.md

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📝 Walkthrough

Walkthrough

The documentation now describes regional availability for managed Postgres and Managed Redis across AWS, Azure, and GCP, including Azure location selection guidance.

Changes

Regional availability guidance

Layer / File(s)	Summary
Provider regional availability docs/providers/aws.md, docs/providers/azure.md, docs/providers/gcp.md	Provider pages describe managed service availability by region. Azure guidance covers VM SKU capacity limits and alternate AZURE_LOCATION values.
Managed storage region guidance docs/concepts/managed-storage/managed-postgres.mdx, docs/concepts/managed-storage/managed-redis.md	Managed Postgres and Managed Redis pages summarize cloud-specific regional support and link to Azure availability guidance.

Priority: ⬇️ Low — Defer this documentation update because it adds regional availability guidance without changing product behavior.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Merge Risk: ⚪ Minimal · up to be704

The documentation-only regional availability guidance is ready to merge with no established blocking risk.

Suggested reviewers: lionello

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: documenting Postgres and Redis region availability by cloud provider.
Linked Issues check	✅ Passed	The documentation addresses issue #423 by describing managed Postgres and Redis availability for AWS, GCP, and Azure. It covers regional limitations and links to live provider availability guidance in…
Out of Scope Changes check	✅ Passed	All changes are documentation updates directly related to managed Postgres and Redis regional availability. No unrelated changes are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…

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