Container Apps Troubleshooting

Common Issues Matrix

Image Pull Failures

Diagnose:

# Check registry configuration
az containerapp show --name APP -g RG --query "properties.configuration.registries"

# Check revision status
az containerapp revision list --name APP -g RG --output table

Fix:

az containerapp registry set \
  --name APP -g RG \
  --server ACR.azurecr.io \
  --identity system

ACR Tasks Disabled (Free Subscriptions)

Symptom: az acr build fails with "ACR Tasks is not supported"

Fix: Build locally instead:

docker build -t ACR.azurecr.io/myapp:v1 .
az acr login --name ACR
docker push ACR.azurecr.io/myapp:v1

Cold Start Issues

Symptom: First request very slow or times out

Fix:

az containerapp update --name APP -g RG --min-replicas 1

Health Probe Failures

Symptom: Container keeps restarting

Check:

# View health probe config
az containerapp show --name APP -g RG --query "properties.configuration.ingress"

# Check if /health endpoint responds
curl https://APP.REGION.azurecontainerapps.io/health

Fix: Ensure app has health endpoint returning 200:

app.get('/health', (req, res) => res.sendStatus(200));

Port Mismatch

Symptom: App starts but returns 502/503

Check:

az containerapp show --name APP -g RG --query "properties.configuration.ingress.targetPort"

Verify: App must listen on this exact port. Check:

• Dockerfile EXPOSE statement
• process.env.PORT or hardcoded port in app

View Logs

# Stream logs (wait for replicas if scale-to-zero)
az containerapp logs show --name APP -g RG --follow

# Recent logs
az containerapp logs show --name APP -g RG --tail 100

# System logs (startup issues)
az containerapp logs show --name APP -g RG --type system

Get All Diagnostic Info

# Combined diagnostic command
echo "=== Container App Diagnostics ===" && \
echo "Revisions:" && az containerapp revision list --name APP -g RG -o table && \
echo "Registry Config:" && az containerapp show --name APP -g RG --query "properties.configuration.registries" && \
echo "Ingress Config:" && az containerapp show --name APP -g RG --query "properties.configuration.ingress" && \
echo "Recent Logs:" && az containerapp logs show --name APP -g RG --tail 20