504 - Gateway Timeout

1// Client-side: Handle 504 with longer timeouts and retries
2async function fetchWithTimeout(url, options = {}, timeout = 60000) {
3const controller = new AbortController();
4  const timeoutId = setTimeout(() => controller.abort(), timeout);
5  
6  try {
7    const response = await fetch(url, {
8      ...options,
9      signal: controller.signal,
10    });
11    
12    clearTimeout(timeoutId);
13    
14    if (response.status === 504) {
15      // Gateway timeout - might be transient, retry once
16      console.warn('Gateway timeout, retrying...');
17      return fetchWithTimeout(url, options, timeout);
18    }
19    
20    return response;
21  } catch (error) {
22    clearTimeout(timeoutId);
23    
24    if (error.name === 'AbortError') {
25      throw new Error('Request timeout');
26    }
27    throw error;
28  }
29}
30
31// For long-running operations, use polling instead
32async function startLongOperation() {
33  // Start async operation
34  const startResponse = await fetch('/api/operations/start', {
35    method: 'POST',
36    headers: { 'Content-Type': 'application/json' },
37    body: JSON.stringify({ type: 'export' }),
38  });
39  
40  const { operationId } = await startResponse.json();
41  
42  // Poll for completion instead of waiting
43  while (true) {
44    const statusResponse = await fetch(`/api/operations/${operationId}`);
45    const { status, result } = await statusResponse.json();
46    
47    if (status === 'completed') {
48      return result;
49    } else if (status === 'failed') {
50      throw new Error('Operation failed');
51    }
52    
53    // Wait before next poll
54    await new Promise(resolve => setTimeout(resolve, 2000));
55  }
56}

1// Server-side: Optimize operations to prevent timeouts
2const express = require('express');
3const app = express();
4
5// Add timeout middleware
6const timeout = (ms) => (req, res, next) => {
7  req.setTimeout(ms, () => {
8    res.status(504).json({
9      error: 'Gateway Timeout',
10      message: 'Request took too long to process',
11    });
12  });
13  next();
14};
15
16// Optimize slow database queries
17app.get('/api/users', timeout(30000), async (req, res) => {
18  try {
19    // Use indexed queries, limit results, add pagination
20    const users = await db.users
21      .find()
22      .select('name email') // Only select needed fields
23      .limit(100) // Limit results
24      .skip((req.query.page || 0) * 100)
25      .lean(); // Faster queries
26    
27    res.json(users);
28  } catch (error) {
29    console.error('Database error:', error);
30    res.status(500).json({ error: 'Internal Server Error' });
31  }
32});
33
34// For long-running operations, use async processing
35app.post('/api/export', async (req, res) => {
36  // Start async job instead of processing synchronously
37  const jobId = await queue.add('export', {
38    userId: req.user.id,
39    filters: req.body.filters,
40  });
41  
42  res.status(202).json({
43    message: 'Export started',
44    jobId: jobId,
45    statusUrl: `/api/jobs/${jobId}`,
46  });
47});
48
49// Check job status
50app.get('/api/jobs/:id', async (req, res) => {
51  const job = await queue.getJob(req.params.id);
52  const status = await job.getState();
53  
54  res.json({
55    id: job.id,
56    status: status,
57    progress: job.progress,
58    result: status === 'completed' ? job.returnvalue : null,
59  });
60});

1# Nginx: Configure longer timeouts for slow operations
2upstream backend {
3    server backend1:3000;
4    server backend2:3000;
5    keepalive 32;
6}
7
8server {
9    listen 80;
10    server_name api.example.com;
11    
12    location /api/ {
13        proxy_pass http://backend;
14        proxy_set_header Host $host;
15        proxy_set_header X-Real-IP $remote_addr;
16        
17        # Increase timeouts for slow operations
18        proxy_connect_timeout 10s;
19        proxy_send_timeout 60s;      # Increased from default 60s
20        proxy_read_timeout 60s;      # Increased from default 60s
21        
22        # Buffer settings for large responses
23        proxy_buffering on;
24        proxy_buffer_size 4k;
25        proxy_buffers 8 4k;
26        proxy_busy_buffers_size 8k;
27        
28        # Don't fail on timeouts immediately
29        proxy_next_upstream timeout;
30        proxy_next_upstream_tries 2;
31    }
32    
33    # Special location for long-running operations
34    location /api/export {
35        proxy_pass http://backend;
36        proxy_read_timeout 300s;    # 5 minutes for exports
37        proxy_send_timeout 300s;
38    }
39}