Files
felhom-agent/internal/capability/probe.go
T

123 lines
5.2 KiB
Go

package capability
import (
"context"
"os"
)
// Status is one capability's live result — the wire shape the agent attaches to its hub report
// (HostReport.Capabilities). The hub mirrors this struct field-for-field and keys its alert on
// Critical+degraded. Reason is empty when ok.
//
// "inactive" (v0.86.0, DR-tier-by-default): a config-GATED capability whose plumbing is HEALTHY
// (binary present, sudo granted) but whose gating feature is disabled by configuration. Distinct
// from degraded on purpose — disabled ≠ broken; the hub renders it as a neutral chip, never red.
// Broken plumbing (binary missing / grant denied) stays DEGRADED even when the gate is off: an
// un-migrated box must never look deliberately disabled.
type Status struct {
Name string `json:"name"`
Feature string `json:"feature"`
Critical bool `json:"critical"`
Status string `json:"status"` // "ok" | "degraded" | "inactive"
Reason string `json:"reason,omitempty"`
}
const (
StatusOK = "ok"
StatusDegraded = "degraded"
StatusInactive = "inactive"
)
// ReasonInactive is the fixed reason string for the inactive state (the hub + operator docs
// reference it verbatim).
const ReasonInactive = "disabled by configuration"
// Runner is the minimal exec seam the probe needs (satisfied by proxmox.ExecRunner). The probe
// runs `sudo -n -l -- <binary> <args…>` LITERALLY — a sudo POLICY LIST that never executes the
// command — so the Runner MUST be a DIRECT runner (RunnerDirect), not the sudo-prepending one
// (else it would double-sudo). exit 0 ⇔ the command is permitted under the NOPASSWD allowlist.
type Runner interface {
Run(ctx context.Context, name string, args ...string) (stdout, stderr []byte, err error)
}
// Prober checks the manifest against the live host. Exists defaults to an os.Stat check on the
// absolute binary path (what `command -v` would resolve for an absolute path) when nil.
// GateActive answers "is the feature behind this gate id configured on?" for GATED capabilities
// (Capability.GatedBy). nil, or a gate it answers true for, keeps the historical behavior; false
// downgrades a HEALTHY probe to StatusInactive (broken plumbing stays degraded regardless).
type Prober struct {
Runner Runner
Exists func(path string) bool // nil → os.Stat
GateActive func(gate string) bool // nil → every gate treated active
}
// Probe lists every manifest capability against the sudo policy and checks its binary exists,
// mapping to ok/degraded (§8 of the spec). It NEVER executes a probed command and NEVER returns a
// fatal error (serve-degraded): a probe failure is reported, not raised. If sudo itself is
// unavailable for the agent (the drop-in is missing / the user has no sudo at all), it collapses
// to ONE aggregate degraded signal instead of N identical ones.
func (p Prober) Probe(ctx context.Context) []Status {
exists := p.Exists
if exists == nil {
exists = func(path string) bool { _, err := os.Stat(path); return err == nil }
}
caps := Manifest()
// Preflight: a bare `sudo -n -l` lists the user's allowed commands. For our NOPASSWD service
// user it exits 0; if it fails, the drop-in isn't installed (or sudo is gone) and EVERY vector
// would individually fail — collapse to one aggregate signal so the operator gets one alert.
if p.Runner != nil {
if _, _, err := p.Runner.Run(ctx, "sudo", "-n", "-l"); err != nil {
return []Status{{
Name: "sudo",
Feature: "the entire privileged surface (mount/format/pct/dnsmasq/lxc-info)",
Critical: true,
Status: StatusDegraded,
Reason: "sudoers drop-in not installed / sudo unavailable",
}}
}
}
out := make([]Status, 0, len(caps))
for _, c := range caps {
s := Status{Name: c.Name, Feature: c.Feature, Critical: c.Critical, Status: StatusOK}
switch {
case !exists(c.Binary):
s.Status, s.Reason = StatusDegraded, "binary not found"
case p.Runner != nil && !p.granted(ctx, c):
s.Status, s.Reason = StatusDegraded, "sudo policy denied"
}
// Config gate (v0.86.0): only a HEALTHY probe is downgraded to inactive — a degraded one
// stays degraded (missing binary/grant = un-migrated or mis-installed box, never "off").
if s.Status == StatusOK && c.GatedBy != "" && p.GateActive != nil && !p.GateActive(c.GatedBy) {
s.Status, s.Reason = StatusInactive, ReasonInactive
}
out = append(out, s)
}
return out
}
// granted reports whether `sudo -n -l -- <binary> <reprArgs…>` is permitted (exit 0). List-mode is
// side-effect-free — the command is matched against the policy, never run.
func (p Prober) granted(ctx context.Context, c Capability) bool {
args := append([]string{"-n", "-l", "--", c.Binary}, c.ReprArgs...)
_, _, err := p.Runner.Run(ctx, "sudo", args...)
return err == nil
}
// Summarize returns (okCount, total, degraded) for logging. degraded lists DEGRADED statuses
// only — inactive is a deliberate, healthy state and must not land in the error log (it is
// counted via len(statuses)-ok-len(degraded) by callers that want it).
func Summarize(statuses []Status) (ok, total int, degraded []Status) {
total = len(statuses)
for _, s := range statuses {
switch s.Status {
case StatusOK:
ok++
case StatusDegraded:
degraded = append(degraded, s)
}
}
return ok, total, degraded
}