fix: add health check for backend connection in middleware #185
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📝 Walkthrough📝 WalkthroughWalkthroughThe changes implemented in this pull request modify the Changes
Sequence Diagram(s)sequenceDiagram
participant Client
participant Middleware
participant Backend
Client->>Middleware: Request
Middleware->>Backend: Fetch /api/v1/health
alt Health Check Success
Middleware-->>Client: Proceed with request
else Health Check Failure
Middleware-->>Client: Redirect to /connect
end
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Actionable comments posted: 3
📜 Review details
Configuration used: CodeRabbit UI
Review profile: ASSERTIVE
📒 Files selected for processing (1)
src/hooks.server.ts(1 hunks)
🧰 Additional context used
🪛 Biome (1.9.4)
src/hooks.server.ts
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
🪛 eslint
src/hooks.server.ts
[error] 37-37: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
[error] 40-40: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
🪛 GitHub Check: Lint
src/hooks.server.ts
[failure] 37-37:
'error' is defined but never used
[failure] 40-40:
'error' is defined but never used
| let hasConnection; | ||
|
|
||
| try { | ||
| await fetch(event.locals.backendUrl + '/api/v1/health') |
There was a problem hiding this comment.
🧹 Nitpick (assertive)
Address linting issues
- Use template literals instead of string concatenation
- Prefix unused error parameters with underscore
Apply these changes:
- await fetch(event.locals.backendUrl + '/api/v1/health')
+ await fetch(`${event.locals.backendUrl}/api/v1/health`)
- .catch((error) => {
+ .catch((_error) => {
- } catch (error) {
+ } catch (_error) {Also applies to: 37-37, 40-40
🧰 Tools
🪛 Biome (1.9.4)
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
src/hooks.server.ts
Outdated
|
|
||
| let hasConnection; | ||
|
|
||
| try { | ||
| await fetch(event.locals.backendUrl + '/api/v1/health') | ||
| .then(() => { | ||
| hasConnection = true; | ||
| }) | ||
| .catch((error) => { | ||
| hasConnection = false; | ||
| }); | ||
| } catch (error) { | ||
| hasConnection = false; | ||
| } | ||
|
|
||
| if (!hasConnection) { | ||
| throw redirect(307, '/connect'); | ||
| } |
There was a problem hiding this comment.
🧹 Nitpick (assertive)
Consider caching health check results
The current implementation performs a health check on every GET request, which could impact performance and put unnecessary load on the backend. Consider implementing a caching mechanism to store the health status for a short duration.
Consider these improvements:
- Add a simple in-memory cache with expiration:
let healthCache: { status: boolean; timestamp: number } | null = null;
const CACHE_DURATION = 30000; // 30 seconds
async function checkHealth(backendUrl: string): Promise<boolean> {
if (healthCache && Date.now() - healthCache.timestamp < CACHE_DURATION) {
return healthCache.status;
}
// Your health check implementation here
healthCache = { status: hasConnection, timestamp: Date.now() };
return hasConnection;
}- Consider implementing a circuit breaker pattern for more robust error handling and backend protection.
🧰 Tools
🪛 Biome (1.9.4)
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
🪛 eslint
[error] 37-37: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
[error] 40-40: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
🪛 GitHub Check: Lint
[failure] 37-37:
'error' is defined but never used
[failure] 40-40:
'error' is defined but never used
src/hooks.server.ts
Outdated
| try { | ||
| await fetch(event.locals.backendUrl + '/api/v1/health') | ||
| .then(() => { | ||
| hasConnection = true; | ||
| }) | ||
| .catch((error) => { | ||
| hasConnection = false; | ||
| }); | ||
| } catch (error) { | ||
| hasConnection = false; | ||
| } |
There was a problem hiding this comment.
🛠️ Refactor suggestion
Improve health check implementation for better reliability and maintainability
The current implementation has several areas for improvement:
- No timeout specified for the fetch request
- Response status is not validated
- Unnecessary nesting of promise chain within try-catch
- Silent error handling without logging
Consider this more robust implementation:
- try {
- await fetch(event.locals.backendUrl + '/api/v1/health')
- .then(() => {
- hasConnection = true;
- })
- .catch((error) => {
- hasConnection = false;
- });
- } catch (error) {
- hasConnection = false;
- }
+ try {
+ const controller = new AbortController();
+ const timeoutId = setTimeout(() => controller.abort(), 5000);
+
+ const response = await fetch(`${event.locals.backendUrl}/api/v1/health`, {
+ signal: controller.signal
+ });
+ clearTimeout(timeoutId);
+
+ hasConnection = response.ok;
+
+ if (!response.ok) {
+ console.error(`Health check failed with status: ${response.status}`);
+ }
+ } catch (error) {
+ console.error('Backend health check failed:', error);
+ hasConnection = false;
+ }📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| try { | |
| await fetch(event.locals.backendUrl + '/api/v1/health') | |
| .then(() => { | |
| hasConnection = true; | |
| }) | |
| .catch((error) => { | |
| hasConnection = false; | |
| }); | |
| } catch (error) { | |
| hasConnection = false; | |
| } | |
| try { | |
| const controller = new AbortController(); | |
| const timeoutId = setTimeout(() => controller.abort(), 5000); | |
| const response = await fetch(`${event.locals.backendUrl}/api/v1/health`, { | |
| signal: controller.signal | |
| }); | |
| clearTimeout(timeoutId); | |
| hasConnection = response.ok; | |
| if (!response.ok) { | |
| console.error(`Health check failed with status: ${response.status}`); | |
| } | |
| } catch (error) { | |
| console.error('Backend health check failed:', error); | |
| hasConnection = false; | |
| } |
🧰 Tools
🪛 Biome (1.9.4)
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
🪛 eslint
[error] 37-37: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
[error] 40-40: 'error' is defined but never used.
(@typescript-eslint/no-unused-vars)
🪛 GitHub Check: Lint
[failure] 37-37:
'error' is defined but never used
[failure] 40-40:
'error' is defined but never used
davidemarcoli
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There was a problem hiding this comment.
Actionable comments posted: 1
📜 Review details
Configuration used: CodeRabbit UI
Review profile: ASSERTIVE
📒 Files selected for processing (1)
src/hooks.server.ts(1 hunks)
🧰 Additional context used
🪛 Biome (1.9.4)
src/hooks.server.ts
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
🔇 Additional comments (2)
src/hooks.server.ts (2)
30-42: Improve health check implementation
The current implementation could be more robust. The previous review comments already provided comprehensive suggestions for improvements, including:
- Adding timeout handling
- Validating response status
- Simplifying promise handling
- Adding proper error logging
🧰 Tools
🪛 Biome (1.9.4)
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
33-33: Use template literals instead of string concatenation
🧰 Tools
🪛 Biome (1.9.4)
[error] 33-33: Template literals are preferred over string concatenation.
Unsafe fix: Use a template literal.
(lint/style/useTemplate)
| if (!hasConnection) { | ||
| throw redirect(307, '/connect'); | ||
| } |
There was a problem hiding this comment.
🧹 Nitpick (assertive)
Consider implementing redirect debouncing
While the redirect logic is correct, frequent health check failures could lead to rapid redirects, potentially causing a poor user experience. Consider implementing a grace period before redirecting.
// Add at the top of the file
let lastRedirectTime = 0;
const REDIRECT_COOLDOWN = 5000; // 5 seconds
// Replace the redirect logic
if (!hasConnection) {
const now = Date.now();
if (now - lastRedirectTime > REDIRECT_COOLDOWN) {
lastRedirectTime = now;
throw redirect(307, '/connect');
}
// If within cooldown period, continue with degraded service
console.warn('Backend connection failed but within redirect cooldown period');
}
Summary by CodeRabbit
New Features
/connectroute if the backend service is unreachable.Bug Fixes