ImagePullBackOff on c4-imagepull (hephaisto-chaos)

investigation

model

gpt-oss:120b

steps

6

tool calls

5

tokens

68.9k in / 2.1k out

cost

$0.0024

confidence

0.95

ended

Concluded

trace

1. 1 llm model turn internal 15.8s · 9.5k tok · $0.0003

   model output — its reasoning, and the tools it asked for

   -> calls get_events

2. 2 tool get_events kubernetes 0ms · 1.0 KiB

   arguments

   {"namespace":"hephaisto-chaos","objectName":"c4-imagepull-7fd88fdb68-5n8sf"}

   result digest — what the model actually saw

   [step 01a05ef8-6db3-7fa8-bd82-42c81919f232] get_events
   log digest: 8 lines, 1045 bytes
   
   -- last 8 lines --
   type     reason     count  objects                            first  last  message
   -------  ---------  -----  ---------------------------------  -----  ----  ------------------------------------------------------------------------------------------------
   Normal   BackOff    11     Pod/c4-imagepull-7fd88fdb68-5n8sf  0s     0s    Back-off pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     11     Pod/c4-imagepull-7fd88fdb68-5n8sf  0s     0s    Error: ImagePullBackOff
   Normal   Pulling    4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Failed to pull image "busybox:this-tag-does-not-exist": Error response from daemon: failed to r…
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Error: ErrImagePull
   Normal   Scheduled  1      Pod/c4-imagepull-7fd88fdb68-5n8sf  2m     2m    Successfully assigned hephaisto-chaos/c4-imagepull-7fd88fdb68-5n8sf to lima-rancher-desktop
   

3. 3 llm model turn internal 2.5s · 9.9k tok · $0.0003

   model output — its reasoning, and the tools it asked for

   -> calls describe_pod

4. 4 tool describe_pod kubernetes 0ms · 4.9 KiB ~ truncated

   arguments

   {"name":"c4-imagepull-7fd88fdb68-5n8sf","namespace":"hephaisto-chaos"}

   result digest — what the model actually saw

   [step 01a05ef8-7777-7cdd-b472-4e869f8bf691] describe_pod
   log digest: 155 lines, 4972 bytes
   
   -- repeated patterns --
   x6 [#89 .. #132]     observedGeneration: 1
   x5 [#33 .. #143]         cpu: 100m
   x5 [#88 .. #108]   - lastTransitionTime: "2026-08-29T13:50:12Z"
   x3 [#37 .. #144]         memory: 16Mi
   x3 [#90 .. #110]     status: "True"
   x2 [#1 .. #80] apiVersion: v1
   x2 [#20 .. #21]     uid: fd16648a-a288-440d-a8af-1ae4b8878d45
   x2 [#30 .. #116]     name: app
   x2 [#31 .. #138]     resources:
   x2 [#32 .. #139]       limits:
   
   -- last 40 lines --
       name: app
       ready: false
       restartCount: 0
       started: false
       state:
         waiting:
           message: 'Back-off pulling image "busybox:this-tag-does-not-exist": ErrImagePull: Error response from daemon: failed to resolve reference "docker.io/library/busybox:this-tag-does-not-exist": docker.io/library/busybox:this-tag-does-not-exist: not found'
           reason: ImagePullBackOff
       volumeMounts:
       - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
         name: kube-api-access-kcgmd
         readOnly: true
         recursiveReadOnly: Disabled
     hostIP: 0.0.0.0
     hostIPs:
     - ip: 0.0.0.0
     observedGeneration: 1
     phase: Pending
     podIP: 0.0.0.0
     podIPs:
     - ip: 0.0.0.0
     qosClass: Burstable
     resources:
       limits:
         cpu: 100m
         memory: 64Mi
       requests:
         cpu: 10m
         memory: 16Mi
     startTime: "2026-08-29T13:50:12Z"
   
   events for this pod:
   type     reason     count  objects                            first  last  message
   -------  ---------  -----  ---------------------------------  -----  ----  ------------------------------------------------------------------------------------------------
   Normal   BackOff    11     Pod/c4-imagepull-7fd88fdb68-5n8sf  3s     3s    Back-off pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     11     Pod/c4-imagepull-7fd88fdb68-5n8sf  3s     3s    Error: ImagePullBackOff
   Normal   Pulling    4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Failed to pull image "busybox:this-tag-does-not-exist": Error response from daemon: failed to r…
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Error: ErrImagePull
   Normal   Scheduled  1      Pod/c4-imagepull-7fd88fdb68-5n8sf  2m     2m    Successfully assigned hephaisto-chaos/c4-imagepull-7fd88fdb68-5n8sf to lima-rancher-desktop
   
   [truncated: 105 of 155 lines omitted]
   

   raw result — the untruncated tool output (4.8 KiB)

   apiVersion: v1
   kind: Pod
   metadata:
     creationTimestamp: "2026-08-29T13:50:12Z"
     generateName: c4-imagepull-7fd88fdb68-
     generation: 1
     labels:
       app.kubernetes.io/name: c4-imagepull
       hephaisto.chaos/fault: imagepull
       hephaisto.chaos/scenario: c4
       pod-template-hash: 7fd88fdb68
     name: c4-imagepull-7fd88fdb68-5n8sf
     namespace: hephaisto-chaos
     ownerReferences:
     - apiVersion: apps/v1
       kind: ReplicaSet
       blockOwnerDeletion: true
       controller: true
       name: c4-imagepull-7fd88fdb68
       uid: fd16648a-a288-440d-a8af-1ae4b8878d45
     uid: 44d056f1-4162-4616-9e45-e8271816dbba
   spec:
     containers:
     - command:
       - /bin/sh
       - -c
       - sleep 86400
       image: busybox:this-tag-does-not-exist
       imagePullPolicy: IfNotPresent
       name: app
       resources:
         limits:
           cpu: 100m
           memory: 64Mi
         requests:
           cpu: 10m
           memory: 16Mi
       terminationMessagePath: /dev/termination-log
       terminationMessagePolicy: File
       volumeMounts:
       - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
         name: kube-api-access-kcgmd
         readOnly: true
     dnsPolicy: ClusterFirst
     enableServiceLinks: true
     nodeName: lima-rancher-desktop
     preemptionPolicy: PreemptLowerPriority
     priority: 0
     restartPolicy: Always
     schedulerName: default-scheduler
     securityContext: {}
     serviceAccount: default
     serviceAccountName: default
     terminationGracePeriodSeconds: 1
     tolerations:
     - effect: NoExecute
       key: node.kubernetes.io/not-ready
       operator: Exists
       tolerationSeconds: 300
     - effect: NoExecute
       key: node.kubernetes.io/unreachable
       operator: Exists
       tolerationSeconds: 300
     volumes:
     - name: kube-api-access-kcgmd
       projected:
         defaultMode: 420
         sources:
         - serviceAccountToken:
             expirationSeconds: 3607
             path: token
         - configMap:
             items:
             - key: ca.crt
               path: ca.crt
             name: kube-root-ca.crt
         - downwardAPI:
             items:
             - fieldRef:
                 apiVersion: v1
                 fieldPath: metadata.namespace
               path: namespace
   status:
     allocatedResources:
       cpu: 10m
       memory: 16Mi
     conditions:
     - lastTransitionTime: "2026-08-29T13:50:12Z"
       observedGeneration: 1
       status: "True"
       type: PodReadyToStartContainers
     - lastTransitionTime: "2026-08-29T13:50:12Z"
       observedGeneration: 1
       status: "True"
       type: Initialized
     - lastTransitionTime: "2026-08-29T13:50:12Z"
       message: 'containers with unready status: [app]'
       observedGeneration: 1
       reason: ContainersNotReady
       status: "False"
       type: Ready
     - lastTransitionTime: "2026-08-29T13:50:12Z"
       message: 'containers with unready status: [app]'
       observedGeneration: 1
       reason: ContainersNotReady
       status: "False"
       type: ContainersReady
     - lastTransitionTime: "2026-08-29T13:50:12Z"
       observedGeneration: 1
       status: "True"
       type: PodScheduled
     containerStatuses:
     - image: busybox:this-tag-does-not-exist
       imageID: ""
       lastState: {}
       name: app
       ready: false
       restartCount: 0
       started: false
       state:
         waiting:
           message: 'Back-off pulling image "busybox:this-tag-does-not-exist": ErrImagePull: Error response from daemon: failed to resolve reference "docker.io/library/busybox:this-tag-does-not-exist": docker.io/library/busybox:this-tag-does-not-exist: not found'
           reason: ImagePullBackOff
       volumeMounts:
       - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
         name: kube-api-access-kcgmd
         readOnly: true
         recursiveReadOnly: Disabled
     hostIP: 0.0.0.0
     hostIPs:
     - ip: 0.0.0.0
     observedGeneration: 1
     phase: Pending
     podIP: 0.0.0.0
     podIPs:
     - ip: 0.0.0.0
     qosClass: Burstable
     resources:
       limits:
         cpu: 100m
         memory: 64Mi
       requests:
         cpu: 10m
         memory: 16Mi
     startTime: "2026-08-29T13:50:12Z"
   
   events for this pod:
   type     reason     count  objects                            first  last  message
   -------  ---------  -----  ---------------------------------  -----  ----  ------------------------------------------------------------------------------------------------
   Normal   BackOff    11     Pod/c4-imagepull-7fd88fdb68-5n8sf  3s     3s    Back-off pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     11     Pod/c4-imagepull-7fd88fdb68-5n8sf  3s     3s    Error: ImagePullBackOff
   Normal   Pulling    4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Pulling image "busybox:this-tag-does-not-exist"
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Failed to pull image "busybox:this-tag-does-not-exist": Error response from daemon: failed to r…
   Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Error: ErrImagePull
   Normal   Scheduled  1      Pod/c4-imagepull-7fd88fdb68-5n8sf  2m     2m    Successfully assigned hephaisto-chaos/c4-imagepull-7fd88fdb68-5n8sf to lima-rancher-desktop
   

5. 5 llm model turn internal 3.1s · 10.8k tok · $0.0003

   model output — its reasoning, and the tools it asked for

   -> calls get_workload

6. 6 tool get_workload kubernetes 0ms · 944 B

   arguments

   {"kind":"Deployment","name":"c4-imagepull","namespace":"hephaisto-chaos"}

   result digest — what the model actually saw

   [step 01a05ef8-839f-7d22-bbf3-a6f34730a870] get_workload
   log digest: 16 lines, 944 bytes
   
   -- last 16 lines --
   Deployment hephaisto-chaos/c4-imagepull  age 2m
   revision: 1
   replicas: desired=1 ready=0 updated=1 available=0 unavailable=1
   strategy: RollingUpdate
   generation: 1 (observed - the controller is acting on the current spec)
   
   conditions:
   type         status  reason                      message                                               since
   -----------  ------  --------------------------  ----------------------------------------------------  -----
   Available    False   MinimumReplicasUnavailable  Deployment does not have minimum availability.        2m
   Progressing  True    ReplicaSetUpdated           ReplicaSet "c4-imagepull-7fd88fdb68" is progressing.  2m
   
   containers (from the pod template):
   container  image                            requests             limits
   ---------  -------------------------------  -------------------  --------------------
   app        busybox:this-tag-does-not-exist  cpu=10m,memory=16Mi  cpu=100m,memory=64Mi
   

7. 7 llm model turn internal 15.6s · 11.9k tok · $0.0005

   model output — its reasoning, and the tools it asked for

   -> calls conclude

8. 8 tool conclude internal 0ms · 129 B x failed

   x The arguments dictionary is missing a value for the required parameter 'request'. (Parameter 'arguments')

   arguments

   {"findings":[{"category":"image","confidence":0.95,"evidence":[{"excerpt":"Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Failed to pull image \u0022busybox:this-tag-does-not-exist\u0022: Error response from daemon: failed to r\u2026","step_id":"01a05ef8-6db3-7fa8-bd82-42c81919f232"},{"excerpt":"message: \u0027Back-off pulling image \u0022busybox:this-tag-does-not-exist\u0022: ErrImagePull: Error response from daemon: failed to resolve reference \u0022docker.io/library/busybox:this-tag-does-not-exist\u0022: docker.io/library/busybox:this-tag-does-not-exist: not found\u0027","step_id":"01a05ef8-7777-7cdd-b472-4e869f8bf691"},{"excerpt":"app        busybox:this-tag-does-not-exist  cpu=10m,memory=16Mi  cpu=100m,memory=64Mi","step_id":"01a05ef8-839f-7d22-bbf3-a6f34730a870"}],"hypothesis":"Deployment hephaisto-chaos/c4-imagepull references a non-existent image tag busybox:this-tag-does-not-exist, causing ImagePullBackOff."}],"summary":"The c4-imagepull Deployment is stuck in ImagePullBackOff because its pod template specifies the image tag \u0027busybox:this-tag-does-not-exist\u0027, which does not exist in Docker Hub. The kubelet reports a \u0022not found\u0022 error, leading to repeated pull attempts and back\u2011off. Fix by correcting the image reference or publishing the intended tag."}

   result digest — what the model actually saw

   [step 01a05ef8-c05d-7461-bc2c-17d95ad38ba2] conclude
   log digest: 1 lines, 129 bytes
   
   -- last 1 lines --
   ERROR: conclude failed: The arguments dictionary is missing a value for the required parameter 'request'. (Parameter 'arguments')
   

9. 9 llm model turn internal 8.2s · 11.9k tok · $0.0004

   model output — its reasoning, and the tools it asked for

   -> calls conclude

10. 10 tool conclude internal 0ms · 141 B

    arguments

    {"request":{"findings":[{"category":"image","confidence":0.95,"evidence":[{"excerpt":"Warning  Failed     4      Pod/c4-imagepull-7fd88fdb68-5n8sf  1m     1m    Failed to pull image \u0022busybox:this-tag-does-not-exist\u0022: Error response from daemon: failed to r\u2026","step_id":"01a05ef8-6db3-7fa8-bd82-42c81919f232"},{"excerpt":"message: \u0027Back-off pulling image \\\u0022busybox:this-tag-does-not-exist\\\u0022: ErrImagePull: Error response from daemon: failed to resolve reference \\\u0022docker.io/library/busybox:this-tag-does-not-exist\\\u0022: docker.io/library/busybox:this-tag-does-not-exist: not found\u0027","step_id":"01a05ef8-7777-7cdd-b472-4e869f8bf691"},{"excerpt":"app        busybox:this-tag-does-not-exist  cpu=10m,memory=16Mi  cpu=100m,memory=64Mi","step_id":"01a05ef8-839f-7d22-bbf3-a6f34730a870"}],"hypothesis":"Deployment hephaisto-chaos/c4-imagepull references a non-existent image tag busybox:this-tag-does-not-exist, causing ImagePullBackOff."}],"summary":"The c4-imagepull Deployment is stuck in ImagePullBackOff because its pod template specifies the image tag \u0027busybox:this-tag-does-not-exist\u0027, which does not exist in Docker Hub. The kubelet reports a \u0022not found\u0022 error, leading to repeated pull attempts and back\u2011off. Fix by correcting the image reference or publishing the intended tag."}}

    result digest — what the model actually saw

    [step 01a05ef8-e08a-7298-8dc2-e42817f5c741] conclude
    log digest: 1 lines, 141 bytes
    
    -- last 1 lines --
    Conclusion recorded. Your citations are now checked against what the tools actually returned; any that do not match are discarded. Stop here.
    

11. 11 llm model turn internal 7.7s · 12.4k tok · $0.0004

    model output — its reasoning, and the tools it asked for

    **Findings**
    
    | # | Category | Confidence | Evidence |
    |---|----------|------------|----------|
    | 1 | **image** | 0.95 | • `Warning  Failed … Failed to pull image "busybox:this-tag-does-not-exist": Error response from daemon: failed to r…` (step 01a05ef8-6db3-7fa8-bd82-42c81919f232) <br>• `message: 'Back-off pulling image "busybox:this-tag-does-not-exist": ErrImagePull: Error response from daemon: failed to resolve reference "docker.io/library/busybox:this-tag-does-not-exist": docker.io/library/busybox:this-tag-does-not-exist: not found'` (step 01a05ef8-7777-7cdd-b472-4e869f8bf691) <br>• `app        busybox:this-tag-does-not-exist  cpu=10m,memory=16Mi  cpu=100m,memory=64Mi` (step 01a05ef8-839f-7d22-bbf3-a6f34730a870) |
    
    **Hypothesis**
    
    The `c4-imagepull` Deployment in namespace **hephaisto-chaos** references the image tag **busybox:this-tag-does-not-exist**, which does not exist in Docker Hub. The kubelet therefore cannot resolve the image reference, resulting in repeated `ErrImagePull` events and a subsequent `ImagePullBackOff` state for its pod.
    
    **Summary**
    
    The Deployment is stuck because it points to a non‑existent image tag. The kubelet reports “not found” when trying to pull `busybox:this-tag-does-not-exist`, causing the pod to remain in `Pending` with `ImagePullBackOff`. Correct the image reference (use an existing tag or push the intended tag) and the Deployment will become healthy.

12. 12 llm model turn internal 9.8s · 4.5k tok · $0.0001

    model output — its reasoning, and the tools it asked for

    {
      "summary": "The Deployment references a non‑existent image tag (busybox:this-tag-does-not-exist). This is a configuration error that must be corrected by updating the Deployment spec. Restarting pods would not resolve the issue because they would attempt to pull the same invalid image.",
      "no_action_required": true,
      "actions": []
    }

findings 1

plan

The Deployment references a non‑existent image tag (busybox:this-tag-does-not-exist). This is a configuration error that must be corrected by updating the Deployment spec. Restarting pods would not resolve the issue because they would attempt to pull the same invalid image.

No action was proposed. The planner set no_action_required — which is the expected outcome for most incidents, and what the planning prompt tells it to default to.