Hey everyone! I'm diving into setting up an LLM observability tool for our team's first production RAG application. We're on AWS, and I want to follow the principle of least privilege for the IAM roles/policies.
My main concern: I see some tools' quick-start guides asking for overly permissive permissions like `logs:*` or `s3:*`. 😬 In my experience, that's how you end up with audit findings or, worse, a compromised bucket.
For those who've been through this, **what are the *absolute minimum* permissions needed for a typical observability agent that needs to:**
* Send trace data (spans, metrics) to a collector/backend.
* Possibly read CloudWatch Logs for our existing API gateway logs.
* *Not* require access to our model endpoints themselves (the app will handle instrumentation).
Here's my starting point for a policy, heavily restricted. Is this missing anything critical?
```json
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "AllowCloudWatchLogsForLambda",
"Effect": "Allow",
"Action": [
"logs:DescribeLogStreams",
"logs:GetLogEvents"
],
"Resource": "arn:aws:logs:*:*:log-group:/aws/lambda/my-rag-lambda:*"
},
{
"Sid": "AllowXRayPutTrace",
"Effect": "Allow",
"Action": [
"xray:PutTraceSegments",
"xray:PutTelemetryRecords"
],
"Resource": "*"
}
]
}
```
Specific questions:
1. Is `xray:PutTraceSegments` sufficient, or do we also need `xray:GetSamplingRules` for the agent to work properly?
2. If the tool uses an S3 bucket for buffering, would you scope permissions to that single bucket with `s3:PutObject` only, or is more needed?
3. Any major difference in permissions if we use a vendor's SaaS collector vs. self-hosted?
I'm a big believer in locking this down from day one. Would love to hear about real-world minimal policies you're using.
security by default
Your starting point is solid, but you're likely missing the core permissions for sending telemetry. The `logs:DescribeLogStreams` and `logs:GetLogEvents` actions are only for reading existing logs, not for writing trace data. Most agents need to create their own log groups/streams or emit metrics.
You'll need at least `logs:CreateLogGroup`, `logs:CreateLogStream`, and `logs:PutLogEvents` on a specific resource ARN for the agent's own telemetry. Also, check if the tool uses AWS X-Ray; if so, you'll need `xray:PutTraceSegments` and `xray:PutTelemetryRecords`. Your policy should explicitly deny any resource pattern like `*` and scope it to the exact log group ARN you'll be using.
Can you share which specific observability tool you're integrating? The exact permission set can vary slightly depending on whether it's using the OpenTelemetry collector, a proprietary agent, or a vendor's SaaS endpoint.
CostCutter
Spot-on instincts, and your policy snippet is a great start. But you're focusing on reading logs, not writing them. The agent isn't just a reader; it's a publisher.
It'll need to create its own log stream for its diagnostics. Add `logs:CreateLogStream` and `logs:PutLogEvents` for a specific resource ARN, like `arn:aws:logs:region:account:log-group:/your-observability-group:*`. Also, don't forget about X-Ray if you're doing distributed tracing - `xray:PutTraceSegments` is a common one.
Your caution about the wildcards is exactly right. That's how you get a call from security at 2 AM 😅 Which tool are you looking at? The exact list can shift a bit.
Missing the real question. Why does every vendor's agent need to create its own log group? That's just them baking in vendor lock-in. A decent tool should let you point it at an existing log group you control, using a role you've already scoped.
Half these permissions are for the vendor's convenience, not a technical requirement.
Your stack is too complicated.
Your starter policy only covers reading, but you're missing the write actions for the agent's own diagnostics. Add `logs:CreateLogGroup` and `logs:PutLogEvents` at a minimum. Also, scope them to a specific log group ARN for the agent, not a wildcard.
One thing I always check: what's the actual ROI on letting the agent create its own log group? Can you pre-create it and just grant `logs:PutLogEvents`? That's one less permission and keeps you in control.
Ask me about hidden egress costs.