---
name: query-netdata-agents
description: Query Netdata Agents (parents and children) directly via their HTTP API on port 19999. Includes a bearer-token helper that mints, caches, and transparently refreshes a per-agent bearer from a long-lived Netdata Cloud token, and auto-detects bearer-protected agents. Use when the user asks how to call an agent's REST API or Function directly, query an agent's logs/metrics/alerts directly, mint a bearer token from a cloud token, or work around bearer protection.
---

# Query Netdata Agents directly

This skill teaches end-users (and AI assistants helping them) how to
talk to a Netdata Agent's HTTP API directly, including
bearer-protected agents that require an SSO-issued bearer token.

It is the sibling of [`query-netdata-cloud`](../query-netdata-cloud/SKILL.md).
The two skills cover different transports for the same underlying
agent API.

## Index of guides

| Domain | Guide |
|---|---|
| Generic Function invocation | [query-functions.md](./query-functions.md) |
| Logs (`systemd-journal`, `windows-events`, `macos-logs`, `otel-logs`) | [query-logs.md](./query-logs.md) |
| Topology (`topology:snmp`) | [query-topology.md](./query-topology.md) |
| Flows (`flows:netflow`) | [query-flows.md](./query-flows.md) |
| Alerts (v3 paths) | [query-alerts.md](./query-alerts.md) |
| DynCfg (`/api/v3/config`) | [query-dyncfg.md](./query-dyncfg.md) |
| Time-series metrics (`/api/v3/data`) | [query-metrics.md](./query-metrics.md) |
| Node identity, hardware, vnodes | [query-nodes.md](./query-nodes.md) |
| Streaming (parent / child / replication) -- agent-only | [query-streaming.md](./query-streaming.md) |
| **Operational how-tos (live catalog)** | [how-tos/INDEX.md](./how-tos/INDEX.md) |


| Transport | Auth | When to use |
|---|---|---|
| Cloud-proxied (sibling skill) | Cloud token | Default. Works for any team member with cloud access. No agent-side bearer needed. |
| Direct-agent (this skill) | Per-agent bearer (UUID, ~24h TTL) | Power users; lower-latency batch fetches; bypasses the Cloud round-trip; required when Cloud is unavailable. |

For **what** to query (function payloads, body schemas), see the
sibling skill -- the agent and the Cloud proxy expose the same
Function payload shape.

This skill ships shell scripts at
[`scripts/_lib.sh`](./scripts/_lib.sh) that automate the bearer mint
/ cache / refresh / call-function flow. End-users can either use the
scripts as a black box, or read the script source as a reference
implementation.

---

## Mandatory Requirements (READ FIRST)

1. **If you analyze, you author a how-to.** When asked a concrete
   question about an agent that isn't already covered by an
   existing how-to under [`how-tos/`](./how-tos/), you MUST author
   a new how-to and add it to
   [`how-tos/INDEX.md`](./how-tos/INDEX.md) BEFORE completing the
   task. The catalog is **live** -- the next assistant should not
   redo the same analysis. Keep this catalog operator-facing:
   recipes here should explain how to fetch or use Agent data.
   Developer contract validation for topology producers, schemas,
   fixtures, UI adapters, or aggregator handoffs belongs in the
   relevant project developer skill, not in this public skill.
2. **Use the token-safe wrappers.** `agents_query_cloud`,
   `agents_query_agent`, `agents_call_function` from
   [`scripts/_lib.sh`](./scripts/_lib.sh) handle auth internally
   and emit only the response body to stdout. Never write raw
   curl with a literal `Authorization: Bearer $TOKEN` or
   `X-Netdata-Auth: Bearer <uuid>`. Bearers / cloud tokens /
   claim_ids must NEVER reach assistant-captured stdout.
3. **Provide actionable instructions.** End every recommendation
   with a runnable wrapper invocation.
4. **Never request credentials.** Use env-key placeholders
   (`NETDATA_CLOUD_TOKEN`, `AGENT_EVENTS_HOSTNAME`,
   `AGENT_EVENTS_NODE_ID`, etc.) -- the user fills `.env` locally.
5. **Bearer values stay in `.env` and `.local/`.** The bearer
   cache file at `<repo>/.local/audits/query-netdata-agents/
   bearers/<machine_guid>.json` is mode 0600 and gitignored. The
   internal helper `_agents_resolve_bearer` returns it through a
   validated caller-local output variable, never to stdout.
6. **For bearer-protected agents, default to the Cloud-token
   flow** in this skill (it auto-mints + caches the bearer).

---

## Prerequisites

- All [SKILL.md prereqs from `query-netdata-cloud`](../query-netdata-cloud/SKILL.md#prerequisites):
  cloud token, space ID, room ID, node UUID.
- Network access to the agent on port 19999 (or whatever it binds).
  Test with: `curl -sS http://AGENT_HOST:19999/api/v3/info` -- a 200
  with JSON confirms reachability.
- The agent's `claim_id` if you intend to mint a bearer. It's at
  `/api/v3/info` -> `.agents[0].cloud.claim_id`, or with shell
  access at `<netdata-prefix>/var/lib/netdata/cloud.d/claimed_id`.
  For the install-prefix detection rule, see
  [`scripts/_lib.sh`](./scripts/_lib.sh).

`.env` keys consumed (none are added by this skill -- the four
existing `AGENT_EVENTS_*` keys cover the maintainer-facing
agent-events workflow):

| Key | Role |
|---|---|
| `NETDATA_CLOUD_TOKEN` | Cloud REST token used to mint per-agent bearers |
| `NETDATA_CLOUD_HOSTNAME` | Cloud REST host |
| `AGENT_EVENTS_HOSTNAME` | When working with the agent-events node specifically -- ssh + direct-HTTP host (IP or DNS name). NOT the journal namespace (hardcoded `agent-events`). |
| `AGENT_EVENTS_NODE_ID` | Target node UUID for direct calls |
| `AGENT_EVENTS_MACHINE_GUID` | Bearer cache key (one bearer per machine_guid) |

---

## Detect bearer protection

The signal is HTTP `412 Precondition Failed` from the agent for any
authenticated path (e.g. `/host/<uuid>/api/v3/function?...`). The
response body is `You need to be authorized to access this resource`.

```bash
# Probe -- 412 means bearer required, 200 means open access
HOST="agent.example.invalid:19999"
NODE="YOUR_NODE_UUID"

curl -s -o /dev/null -w '%{http_code}\n' -X POST \
  -H 'Content-Type: application/json' \
  "http://$HOST/host/$NODE/api/v3/function?function=systemd-journal" \
  -d '{"info":true}'
```

The unauthenticated `/api/v3/info` endpoint is always reachable
(returns 200 with the agent's identity). Use it to confirm the host
is up before checking auth.

---

## Mint a per-agent bearer

**Endpoint:** `GET /api/v2/bearer_get_token` on Netdata Cloud.

Required query parameters: `node_id`, `machine_guid`, `claim_id`.
Auth: Cloud token in `Authorization: Bearer ...`.

```bash
TOKEN="YOUR_API_TOKEN"
NODE_ID="YOUR_NODE_UUID"
MACHINE_GUID="YOUR_MACHINE_GUID"
CLAIM_ID="YOUR_CLAIM_ID"

curl -sS \
  -H "Authorization: Bearer $TOKEN" \
  "https://app.netdata.cloud/api/v2/bearer_get_token?node_id=$NODE_ID&machine_guid=$MACHINE_GUID&claim_id=$CLAIM_ID"
```

Response body:

| Field | Description |
|---|---|
| `token` | The 36-char UUID bearer; pass to the agent in `X-Netdata-Auth: Bearer <token>` |
| `expiration` | Numeric. Format may be Unix ms or seconds; treat values > 10^12 as ms |
| `bearer_protection` | `true` if the agent IS bearer-protected; the token still works either way |
| `mg` | Echoed `machine_guid` |
| `status` | Status code |

Permission gate (Cloud-side): `PermissionSpaceRead` on the target
space; node must be `reachable`. If the agent is `stale`, the call
returns 400.

---

## Use the bearer to call an agent

```bash
HOST="agent.example.invalid:19999"   # the agent's bind address
NODE="YOUR_NODE_UUID"                # the node UUID (== nd field)
BEARER="MINTED_BEARER_UUID"

curl -sS -X POST \
  -H "X-Netdata-Auth: Bearer $BEARER" \
  -H 'Content-Type: application/json' \
  "http://$HOST/host/$NODE/api/v3/function?function=systemd-journal" \
  -d '{"info":true,"timeout":30000}'
```

Notes:

- The header is **`X-Netdata-Auth: Bearer ...`**, NOT
  `Authorization: Bearer ...`. The agent rejects the latter for
  per-agent bearer auth.
- The agent's HTTP API path mirrors the Cloud-proxied path. For the
  Function payload shape (e.g. `systemd-journal` query body), see
  the matching guide in
  [`query-netdata-cloud`](../query-netdata-cloud/SKILL.md).

---

## Bearer cache and refresh

The shipped scripts cache bearers per `machine_guid` under
`<repo>/.local/audits/query-netdata-agents/bearers/<machine_guid>.json`
(gitignored, mode 0600). Each cache entry stores the raw mint
response.

Refresh policy: the cache is considered expired when
`expiration - now < 3600` (one-hour buffer before actual TTL).
Mirror of the Cloud frontend's policy
(`cloud-frontend/src/domains/nodes/useAgentBearer.js`).

A failed mint clears the cache entry so the next call re-mints from
scratch.

---

## Scripts

The reference implementation lives in
[`scripts/_lib.sh`](./scripts/_lib.sh). It exposes **token-safe
public wrappers** (the assistant never sees the cloud token,
agent bearer, or claim_id on stdout) and a **self-test** that
asserts no token bytes leak.

```bash
# In your script:
source "$(git rev-parse --show-toplevel)/.agents/skills/query-netdata-agents/scripts/_lib.sh"
agents_load_env

# Cloud-side call. NETDATA_CLOUD_TOKEN is read from .env
# internally; stdout is the response body only.
agents_query_cloud GET /api/v2/spaces

# Direct-agent call. The bearer is minted/cached/refreshed
# internally. stdout is the response body only; stderr shows the
# curl invocation with `<CLOUD_TOKEN>` and `<AGENT_BEARER>`
# masked.
agents_query_agent \
    --node "$AGENT_EVENTS_NODE_ID" \
    --host "$AGENT_EVENTS_HOSTNAME:19999" \
    --machine-guid "$AGENT_EVENTS_MACHINE_GUID" \
    POST '/api/v3/function?function=systemd-journal' '{"info":true}'

# Convenience: pick transport with --via cloud|agent.
agents_call_function \
    --via cloud \
    --node "$AGENT_EVENTS_NODE_ID" \
    --function systemd-journal
```

### Public API (assistant-facing)

| Function | Purpose |
|---|---|
| `agents_load_env` | Source `<repo>/.env`; validate required keys |
| `agents_repo_root` | Locate this repo's checkout root |
| `agents_audit_dir` | Create + return `<repo>/.local/audits/query-netdata-agents/` |
| `agents_netdata_prefix` | Autodetect Netdata install prefix (system / `/opt/netdata` / `/usr/local/netdata`) |
| `agents_query_cloud METHOD PATH [BODY]` | Call any Cloud REST endpoint. Auth is added internally. **Stdout = response body only.** |
| `agents_query_agent --node N --host H --machine-guid M METHOD PATH [BODY]` | Call any direct-agent path. Bearer resolved internally. **Stdout = response body only.** |
| `agents_call_function --via cloud\|agent --node N --function F [--body J]` | Convenience wrapper around the two above |
| `agents_run` / `agents_run_read` | Run curl with masked-token argv echo on stderr (used by the wrappers; rarely needed directly) |
| `agents_selftest_no_token_leak` | Self-test: drives the wrappers with a sentinel token and asserts the sentinel never reaches captured stdout |

### Internal helpers (do NOT call directly)

These start with `_` and operate on token bytes inside their own
scope. They return token data through validated caller-local output
variables (so the assistant never sees them on stdout). Don't
shell-out to them.

| Internal | Purpose |
|---|---|
| `_agents_resolve_bearer OUTVAR <node> <mg> <host>` | Cache-aware bearer resolution; writes the bearer into `$OUTVAR` |
| `_agents_get_claim_id OUTVAR <host>` | Resolve `claim_id` from `/api/v3/info`; writes to `$OUTVAR` |
| `_agents_mint_bearer_json <node> <mg> <claim>` | One-shot Cloud bearer mint; the caller MUST capture into a local |
| `_agents_log_masked` | Token / bearer redaction for stderr argv echoes |
| `_agents_exp_to_seconds` | Normalize Cloud `expiration` (sec or ms) to seconds |

---

## Direct-agent vs Cloud-proxied: how `agents_call_function` chooses

Default is `--via cloud` -- the safe choice for any team member.

`--via agent` requires:
1. The agent host is reachable from the workstation on port 19999.
2. A bearer (auto-minted internally via `_agents_resolve_bearer`).

Falls back to `--via cloud` if the direct call fails.

---

## Sensitive data

- Bearer values appear in script stderr only when masked.
- The cache file at `.local/audits/.../bearers/<machine_guid>.json`
  contains the raw bearer; mode 0600.
- Never paste bearer values, claim ids, machine GUIDs, or node UUIDs
  into committed files. See
  `<repo>/.agents/sensitive-data-discipline.md` for the
  full rule.
