1# Container Apps Troubleshooting
2 
3### Common Issues Matrix
4 
5| Symptom | Likely Cause | Quick Fix |
6|---------|--------------|-----------|
7| Image pull failure | ACR credentials missing | `az containerapp registry set --identity system` |
8| ACR build fails | ACR Tasks disabled (free sub) | Build locally with Docker |
9| Cold start timeout | min-replicas=0 | `az containerapp update --min-replicas 1` |
10| Port mismatch | Wrong target port | Check Dockerfile EXPOSE matches ingress |
11| App keeps restarting | Health probe failing | Verify `/health` endpoint |
12 
13### Image Pull Failures
14 
15**Diagnose:**
16```bash
17# Check registry configuration
18az containerapp show --name APP -g RG --query "properties.configuration.registries"
19 
20# Check revision status
21az containerapp revision list --name APP -g RG --output table
22```
23 
24**Fix:**
25```bash
26az containerapp registry set \
27  --name APP -g RG \
28  --server ACR.azurecr.io \
29  --identity system
30```
31 
32### ACR Tasks Disabled (Free Subscriptions)
33 
34**Symptom:** `az acr build` fails with "ACR Tasks is not supported"
35 
36**Fix: Build locally instead:**
37```bash
38docker build -t ACR.azurecr.io/myapp:v1 .
39az acr login --name ACR
40docker push ACR.azurecr.io/myapp:v1
41```
42 
43### Cold Start Issues
44 
45**Symptom:** First request very slow or times out
46 
47**Fix:**
48```bash
49az containerapp update --name APP -g RG --min-replicas 1
50```
51 
52### Health Probe Failures
53 
54**Symptom:** Container keeps restarting
55 
56**Check:**
57```bash
58# View health probe config
59az containerapp show --name APP -g RG --query "properties.configuration.ingress"
60 
61# Check if /health endpoint responds
62curl https://APP.REGION.azurecontainerapps.io/health
63```
64 
65**Fix:** Ensure app has health endpoint returning 200:
66```javascript
67app.get('/health', (req, res) => res.sendStatus(200));
68```
69 
70### Port Mismatch
71 
72**Symptom:** App starts but returns 502/503
73 
74**Check:**
75```bash
76az containerapp show --name APP -g RG --query "properties.configuration.ingress.targetPort"
77```
78 
79**Verify:** App must listen on this exact port. Check:
80- Dockerfile `EXPOSE` statement
81- `process.env.PORT` or hardcoded port in app
82 
83### View Logs
84 
85```bash
86# Stream logs (wait for replicas if scale-to-zero)
87az containerapp logs show --name APP -g RG --follow
88 
89# Recent logs
90az containerapp logs show --name APP -g RG --tail 100
91 
92# System logs (startup issues)
93az containerapp logs show --name APP -g RG --type system
94```
95 
96### Get All Diagnostic Info
97 
98```bash
99# Combined diagnostic command
100echo "=== Container App Diagnostics ===" && \
101echo "Revisions:" && az containerapp revision list --name APP -g RG -o table && \
102echo "Registry Config:" && az containerapp show --name APP -g RG --query "properties.configuration.registries" && \
103echo "Ingress Config:" && az containerapp show --name APP -g RG --query "properties.configuration.ingress" && \
104echo "Recent Logs:" && az containerapp logs show --name APP -g RG --tail 20
105```
106