Datadog Agent Debugging Checklist

📌 Datadog Agent Debugging Checklist

If your Datadog Agent is running without errors but your host is missing from the Datadog UI, follow this guide to diagnose and resolve the issue efficiently.

---

1️⃣ Verify Datadog Agent Status

Run the following command to check if the agent is active:

sudo systemctl status datadog-agent

✅ Expected Output:

● datadog-agent.service - Datadog Agent
   Loaded: loaded (/lib/systemd/system/datadog-agent.service; enabled; vendor preset: enabled)
   Active: active (running) since ...

🚨 If inactive or failed, restart the agent:

sudo systemctl restart datadog-agent

---

2️⃣ Check Agent Logs for Errors

To review logs for potential issues:

sudo journalctl -u datadog-agent --no-pager --lines=50

✅ Look for messages related to:

• API key authentication failures
• Connection refused errors
• Failure to reach Datadog servers

---

3️⃣ Verify API Key & Connectivity

Ensure the API key is correctly set:

sudo grep -oP '(?<=api_key: ).*' /etc/datadog-agent/datadog.yaml

Then, test connectivity manually:

sudo curl -v "https://api.datadoghq.com/api/v1/validate?api_key=$(sudo grep -oP '(?<=api_key: ).*' /etc/datadog-agent/datadog.yaml)"

✅ Expected Response (200 OK):

{"valid":true}

🚨 If response is 403 Forbidden or 401 Unauthorized, the API key is incorrect. Verify and update it in /etc/datadog-agent/datadog.yaml.

---

4️⃣ Check Hostname in Datadog

sudo datadog-agent hostname

✅ Ensure this matches the expected hostname in Datadog UI.

🚨 If incorrect, manually set it in /etc/datadog-agent/datadog.yaml:

hostname: my-hostname

Restart the agent:

sudo systemctl restart datadog-agent

---

5️⃣ Test Network Connectivity Manually

Instead of datadog-agent check connectivity, manually test connectivity:

curl -v https://app.datadoghq.com
curl -v https://api.datadoghq.com

✅ Expected Output: No Connection refused or Timeout errors.

🚨 If blocked, allow outbound traffic:

sudo ufw allow out to api.datadoghq.com

---

6️⃣ Verify Datadog Agent is Sending Data

sudo datadog-agent status | grep -A10 "Forwarder"

✅ Look for:

Transactions flushed: successfully: X, errors: 0

🚨 If errors: X appears, the agent is not sending data. Restart it:

sudo systemctl restart datadog-agent

---

7️⃣ Manually Send a Test Metric

If the agent is running but not visible, manually send a test metric:

sudo datadog-agent telemetry send test.metric 1

✅ Check in Datadog UI → Metrics Explorer and search for test.metric.

---

📌 Summary of Debugging Steps

Check	Command	Expected Result
Agent is running	sudo systemctl status datadog-agent	Active: running
Check logs for errors	sudo journalctl -u datadog-agent --no-pager --lines=50	No connection/auth errors
Verify API key	sudo grep -oP '(?<=api_key: ).*' /etc/datadog-agent/datadog.yaml	Matches correct API key
Test Datadog connectivity	curl -v https://api.datadoghq.com	No network errors
Check hostname	sudo datadog-agent hostname	Matches expected hostname
Check network reachability	ping api.datadoghq.com	Successful ping
Ensure metrics are sent	`sudo datadog-agent status	grep -A10 "Forwarder"`	No errors in transactions
Manually send a test metric	sudo datadog-agent telemetry send test.metric 1	Appears in Datadog UI

---

🚀 Follow these steps to ensure your non-containerized host appears in the Datadog UI! Need more help? Drop a comment or reach out! 🚀