fix: use HYPERCODE_REDIS_URL env var in MultiTierCache default (#196) by welshDog · Pull Request #196 · welshDog/HyperCode-V2.4

welshDog · 2026-05-01T14:45:05Z

🐛 Problem

MultiTierCache.__init__ had a hardcoded default:

redis_url: str = "redis://redis:6379/1"  # no auth!

On Railway, Redis requires a password (from HYPERCODE_REDIS_URL). The hardcoded URL had no password → server returned NOAUTH Authentication required → app fell back to local-cache-only mode.

Meanwhile main.py (metrics Redis client) was already using settings.HYPERCODE_REDIS_URL correctly — so you had two Redis clients using two different configs.

✅ Fix

Changed redis_url default to None and resolve via env var — same pattern as the working client:

def __init__(
    self,
    local_size: int = 1000,
    local_ttl: int = 300,
    redis_url: str | None = None,  # ← resolve from env
):
    self.redis_url = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1")

📋 Impact

Eliminates Redis connection failed: Authentication required warning on Railway
MultiTierCache will now connect to Redis with full auth
redis://redis:6379/1 still works as a last-resort local fallback
Zero breaking changes — existing callers unaffected

🧪 Expected log change after deploy

Before: ⚠️ Redis connection failed: Authentication required.. Using local cache only.
After: ✅ Redis cache connected

Summary by CodeRabbit

Chores
- Cache configuration now supports optional environment variable for Redis connection URL, providing sensible automatic defaults when explicit configuration is not supplied.
- Improves operational flexibility by simplifying configuration management across different deployment environments.
- Reduces setup complexity for standard deployments whilst maintaining configurability for specialised environments.
- Documentation updated to reflect the new configuration approach and available options.

The __init__ default redis_url was hardcoded to redis://redis:6379/1 with no auth, causing NOAUTH Authentication required on Railway where Redis requires a password. Fix: default to None and resolve via os.getenv("HYPERCODE_REDIS_URL") with the old URL as last-resort fallback — same pattern as main.py. Also fixes get_cache() call site to pass the env var explicitly.

coderabbitai · 2026-05-01T14:45:20Z

📝 Walkthrough

Walkthrough

The MultiTierCache class now accepts an optional redis_url parameter that defaults to None. When not provided, the connection URL is resolved from the HYPERCODE_REDIS_URL environment variable, falling back to redis://redis:6379/1. The singleton initialization documentation has been updated accordingly.

Changes

Cohort / File(s)	Summary
Redis Configuration `backend/app/cache/multi_tier.py`	Modified `MultiTierCache.__init__()` to accept optional `redis_url` parameter (`str \| None`) instead of a default string value. Connection URL now derived from `HYPERCODE_REDIS_URL` environment variable with fallback to `redis://redis:6379/1` when omitted.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

A rabbit hops through config land,
Where env vars lend a helping hand,
No hardcoded paths to slow us down,
Just flexibility all around! 🐰✨

🚥 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 pull request title accurately describes the main change: using the HYPERCODE_REDIS_URL environment variable as the default for MultiTierCache's redis_url parameter.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

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🧪 Generate unit tests (beta)

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Commit unit tests in branch fix/multi-tier-cache-redis-auth

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🔧 OpenGrep (1.20.0)

backend/app/cache/multi_tier.py

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coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@backend/app/cache/multi_tier.py`:
- Line 47: self.redis_url is set using os.getenv which returns an empty string
if HYPERCODE_REDIS_URL is present but empty, causing silent fallback to local
cache; change the assignment in the constructor to treat empty/whitespace values
as unset by checking truthiness/stripped content. Concretely, compute candidate
= redis_url if redis_url and redis_url.strip() else
os.getenv("HYPERCODE_REDIS_URL") and then set self.redis_url = candidate.strip()
if candidate and candidate.strip() else "redis://redis:6379/1" so that both an
empty env var and an empty argument correctly fall back to the default.

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Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: bc326467-7326-4219-9371-282781a6e424

📥 Commits

Reviewing files that changed from the base of the PR and between 7e16476 and b02c2f1.

📒 Files selected for processing (1)

backend/app/cache/multi_tier.py

coderabbitai · 2026-05-01T14:49:25Z

        """
        self.local_cache = TTLCache(maxsize=local_size, ttl=local_ttl)
-        self.redis_url = redis_url
+        self.redis_url = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1")


⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash # Verify current expression behaviour when env var is empty. python - <<'PY' import os os.environ["HYPERCODE_REDIS_URL"] = "" redis_url = None resolved = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1") print("resolved =", repr(resolved)) # Expected with current code: '' (shows fallback is skipped) PY

Repository: welshDog/HyperCode-V2.4

Length of output: 81

🏁 Script executed:

git ls-files backend/app/cache/multi_tier.py

Repository: welshDog/HyperCode-V2.4

Length of output: 99

🏁 Script executed:

cat -n backend/app/cache/multi_tier.py | head -60 | tail -25

Repository: welshDog/HyperCode-V2.4

Length of output: 1116

🏁 Script executed:

rg "HYPERCODE_REDIS_URL|redis_url" -A 2 -B 2

Repository: welshDog/HyperCode-V2.4

Length of output: 50381

Empty HYPERCODE_REDIS_URL bypasses fallback to default Redis URL.

When the environment variable is present but empty or whitespace-only, os.getenv() returns the empty value before the default is ever evaluated. This causes self.redis_url to be set to an empty string instead of falling back to redis://redis:6379/1, silently disabling Redis connectivity and reverting to local-cache-only mode.

Suggested fix

- self.redis_url = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1") + configured_url = (redis_url or os.getenv("HYPERCODE_REDIS_URL") or "").strip() + self.redis_url = configured_url or "redis://redis:6379/1"

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

self.redis_url = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1")

configured_url = (redis_url or os.getenv("HYPERCODE_REDIS_URL") or "").strip()

self.redis_url = configured_url or "redis://redis:6379/1"

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed. In `@backend/app/cache/multi_tier.py` at line 47, self.redis_url is set using os.getenv which returns an empty string if HYPERCODE_REDIS_URL is present but empty, causing silent fallback to local cache; change the assignment in the constructor to treat empty/whitespace values as unset by checking truthiness/stripped content. Concretely, compute candidate = redis_url if redis_url and redis_url.strip() else os.getenv("HYPERCODE_REDIS_URL") and then set self.redis_url = candidate.strip() if candidate and candidate.strip() else "redis://redis:6379/1" so that both an empty env var and an empty argument correctly fall back to the default.

coderabbitai Bot reviewed May 1, 2026

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fix: use HYPERCODE_REDIS_URL env var in MultiTierCache default (#196)#196

fix: use HYPERCODE_REDIS_URL env var in MultiTierCache default (#196)#196
welshDog wants to merge 1 commit into
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fix/multi-tier-cache-redis-auth

welshDog commented May 1, 2026 •

edited by coderabbitai Bot

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	self.redis_url = redis_url or os.getenv("HYPERCODE_REDIS_URL", "redis://redis:6379/1")
	configured_url = (redis_url or os.getenv("HYPERCODE_REDIS_URL") or "").strip()
	self.redis_url = configured_url or "redis://redis:6379/1"

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welshDog commented May 1, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

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🐛 Problem

✅ Fix

📋 Impact

🧪 Expected log change after deploy

Summary by CodeRabbit

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welshDog commented May 1, 2026 •

edited by coderabbitai Bot

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