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fix(watcher): repair pod peer IP identity misses during churn - #1002
Under rapid pod churn (deployments rolling out, scaling events, job completions), Inspektor Gadget's K8sInventoryCache can occasionally miss newly assigned peer pod IPs or experience lookahead misses while informers catch up. When this occurs, network events are emitted with empty destination pod labels and namespaces, preventing peer selector rules from matching and causing false-positive network alerts or incomplete network neighborhoods.
This PR introduces peerRepair into NetworkTracer:
When an IP is not found in the inventory or misses pod labels, it queries local pod inventories and maintains a short TTL cache (30s hit TTL, 10s miss TTL).
Automatically repairs the datasource event's destination pod metadata and labels before dispatching to downstream handlers and CEL evaluators.
Properly handles IP reuse when pods terminate and IPs are recycled.
Extracted as part of the upstreaming roadmap from entlein's work.
Testing
Unit test TestPeerRepair_ReusedAddressResolvesToTheCurrentPod verifies address recycling and label restoration.
Summary by CodeRabbit
New Features
Network events can now include Kubernetes pod details for destination endpoints when that information is missing, including pod name, namespace, kind, and labels.
Existing endpoint details are preserved when they are already available, and ambiguous matches are left unresolved.
NetworkTracer now applies peer repair to subscribed network events. Peer repair looks up destination pod identity in Kubernetes inventory, caches lookup results, and fills eligible endpoint metadata before the event reaches the callback.
Changes
Network Peer Repair
Layer / File(s)
Summary
Pod lookup and cache pkg/containerwatcher/v2/tracers/peer_repair.go, pkg/containerwatcher/v2/tracers/peer_repair_test.go
Peer lookup excludes host-network pods, uses expected identity to resolve ambiguous matches, and caches positive and negative results with expiration and capacity limits. Tests cover ownership changes, cache behavior, indexed lookup, and label refresh.
Endpoint repair and event integration pkg/containerwatcher/v2/tracers/peer_repair.go, pkg/containerwatcher/v2/tracers/network.go, pkg/containerwatcher/v2/tracers/peer_repair_test.go
Peer repair fills pod metadata for eligible destination endpoints. NetworkTracer initializes peer repair and passes event data through it before invoking the callback. Tests cover repaired endpoints and endpoints that remain unchanged.
sequenceDiagram
participant Datasource
participant NetworkTracer
participant peerRepair
participant KubernetesInventory
participant NetworkCallback
Datasource->>NetworkTracer: subscribed event data
NetworkTracer->>peerRepair: repair destination endpoint
peerRepair->>KubernetesInventory: retrieve pods for endpoint lookup
KubernetesInventory-->>peerRepair: pod inventory
peerRepair-->>NetworkTracer: repair result and updated data
NetworkTracer->>NetworkCallback: network event
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The title clearly and concisely describes the main change: repairing pod peer IP identity misses during pod churn.
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The normal resolver-miss path is skipped here. The configured Inspektor Gadget KubeIPResolver writes EndpointKindRaw when GetPodByIp misses, and it runs before this operator (priority 10 versus 50000), so these events arrive with ep.Kind == "raw", not an empty kind. Consequently, the fallback never repairs the full inventory misses described by this PR. Treat EndpointKindRaw as unresolved while continuing to preserve service and other resolved kinds.
GetPods() includes both current and recently deleted cached-map values, and those values are produced by unordered map iteration. During IP reuse, the terminating pod and its replacement can therefore both match this address, so returning the first one nondeterministically caches and emits the stale identity—the churn case this repair is meant to fix. Detect ambiguous matches and decline repair, or disambiguate them with the expected namespace/name (or another authoritative current-owner signal); the reuse test should retain both pods instead of replacing the old slice element.
Every positive cache hit calls GetPods() and scans the entire cluster pod inventory while holding the global repair mutex. The inventory implementation allocates a full values slice, so this makes each network event O(number of pods) and serializes concurrent callbacks—the hit cache no longer protects this hot path in large clusters. Prefer indexed GetPodByName/GetPodByIp validation and reserve the full scan for an index miss or ambiguity.
This ownership check returns the cached label string even when the current pod's labels have changed. Pods can be relabeled without changing name, namespace, or IP, so repaired events can carry stale selector labels for up to 30 seconds and produce incorrect rule matches. Refresh the cached labels from the validated pod before returning.
Negative entries are keyed only by IP, even when the miss was caused by an expectedName mismatch rather than by absence of an IP owner. A stale partially enriched event can therefore cache a miss for a recycled address, and subsequent raw or correctly named events will skip the current pod for 10 seconds. Scope identity-constrained misses by the expected identity, or do not reuse them for lookups with different expectations.
This issue also appears in the following locations of the same file:
K8sInventoryCache.Start is reference-counted in the pinned dependency: every call increments its use count, and only a matching Stop decrements it and shuts down the informers/cache. This new owner starts the cache, but NetworkTracer.Stop only cancels the gadget, so shutdown leaves this reference and its resources alive. Pair this start with exactly one stop when the tracer is stopped.
Indexed raw lookup bypasses recycled IP ambiguity handling
The indexed raw lookup returns a single pod even while GetPods contains both pods claiming a recycled IP, so this bypasses the ambiguity handling in podByIP and enriches an unresolved event with whichever indexed identity won. Raw lookups must consult the complete pod set before deciding the address is unambiguous.
This fallback no longer verifies that the named pod owns ip. If the endpoint carries stale pod metadata after address reuse, it can find the old pod at a different (or empty) PodIP, cache that identity under the recycled address, and rewrite the event with stale labels. Keep the IP ownership check on this path as well.
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Actionable comments posted: 2
🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @pkg/containerwatcher/v2/tracers/peer_repair.go:
- Around line 153-156: Update repair so pruneExpired is not called under r.mu
for every network event; prune only at cache capacity or on a maintenance timer,
while preserving per-entry TTL checks at lookup. Where feasible, move the
cache-miss pod scan out of the global lock.
- Around line 220-230: Remove the name-only fallback in lookupWithExpected after
the IP-and-identity lookup fails. Only set the identity from a pod that matches
the lookup IP and expected identity; otherwise preserve the not-found result to
avoid caching a stale pod identity.
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… (5396498806)
- Validate positive cache hits against current pod inventory even on raw upstream misses
- Ensure rapid IP churn is detected immediately without waiting for hit TTL expiration
- Update tests to verify immediate IP churn detection without time advancement
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…back (5396556944)
- Allow endpoints with EndpointKindRaw (emitted on KubeIPResolver misses) through to fallback repair
- Preserve non-pod kinds like EndpointKindService and fully enriched pods
- Add unit tests for EndpointKindRaw and empty kind fallback repair
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…5396614062)
- Disambiguate duplicate IP matches using expected pod identity when both old and new pods exist in inventory
- Decline repair on ambiguous matches without an authoritative pod name to prevent nondeterministic stale attribution
- Add unit tests verifying duplicate candidate disambiguation and raw ambiguity decline
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…abeled pods (5396673309)
- Validate cached hits via O(1) indexed GetPodByName instead of full pod list scans
- Refresh cached labels from validated pod to avoid stale selector labels after pod relabeling
- Add unit tests for label refreshing on relabeling and indexed inventory validation
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…tive cache (5396728761)
- Do not cache negative IP entries when lookup is constrained by expected pod identity
- Invalidate and bypass negative cache entries when an expected identity is provided
- Add unit test verifying identity-constrained misses do not poison subsequent raw lookups
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…nd preserve raw ambiguity handling (5396789312)
- Call peerRepair.stop() from NetworkTracer.Stop() to decrement reference-counted K8sInventoryCache
- Consult full pod inventory for raw lookups to preserve recycled IP ambiguity detection
- Enforce IP ownership check and remove unsafe fallback by name on recycled addresses
- Add unit tests for stop lifecycle, ambiguous IP raw repair decline, and stale expected identity handling
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…dexed hit validation (5396862939)
- Record stopped state under mutex and refuse late inventory initialization after stop
- Validate positive cache hits in O(1) via GetPodByName and GetPodByIp without scanning all pods
- Add unit tests for stop late-init prevention and raw cache hit invalidation on IP recycling
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
- Use standard hashicorp/golang-lru/v2/expirable for positive (30s) and negative (10s) peer caches
- Eliminate manual pruneExpired, evictOldest, and custom TTL management
- Simplify invalidate and cache hit/miss paths while retaining churn ambiguity handling
- Update unit tests to verify LRU-backed caches
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
…k (4169899151)
- Scope r.mu exclusively to stopped/inventory lifecycle transitions
- Eliminate recursive mutex acquisition in lookupWithExpected and r.pods()
- Rely on thread-safe expirable.LRU for concurrent cache access without global lock
Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
If inventory creation fails (notably the no-kubeconfig case), inventory remains nil and this retries initInv for every unresolved network event. The pinned inventory singleton memoizes its initialization error with sync.Once, so these retries cannot recover; they only emit the warning on the event hot path indefinitely. Memoize the failed attempt (or rate-limit/back off it) so Kubernetes enrichment degrades once instead of flooding logs.
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Description
Under rapid pod churn (deployments rolling out, scaling events, job completions), Inspektor Gadget's
K8sInventoryCachecan occasionally miss newly assigned peer pod IPs or experience lookahead misses while informers catch up. When this occurs, network events are emitted with empty destination pod labels and namespaces, preventing peer selector rules from matching and causing false-positive network alerts or incomplete network neighborhoods.This PR introduces
peerRepairintoNetworkTracer:Extracted as part of the upstreaming roadmap from entlein's work.
Testing
TestPeerRepair_ReusedAddressResolvesToTheCurrentPodverifies address recycling and label restoration.Summary by CodeRabbit