Runtime panic while trying to upgrade to 1.20.0

[wavemoran]

Describe the bug

I'm experiencing a panic runtime error in flux while trying to upgrade from flux 1.19.0 to 1.20.0 (logs below). Pod goes into a CrashLoopBackOff. Rolling back the deployment to version 1.19.0 fixes the issue.

To Reproduce

Steps to reproduce the behaviour:

1. Update image version to 1.20.0

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: flux
  namespace: weave
spec:
  replicas: 1
  selector:
    matchLabels:
      name: flux
  strategy:
    type: Recreate
  template:
    metadata:
      annotations:
        prometheus.io/port: "3031"
      labels:
        name: flux
    spec:
      nodeSelector:
        beta.kubernetes.io/os: linux
      serviceAccountName: flux
      volumes:
      - name: git-key
        secret:
          secretName: flux-git-deploy
          defaultMode: 0400
      - name: git-keygen
        emptyDir:
          medium: Memory
      containers:
      - name: flux
        image: docker.io/fluxcd/flux:1.20.0
        imagePullPolicy: Always
        resources:
          requests:
            cpu: 50m
            memory: 64Mi
        ports:
        - containerPort: 3030
        livenessProbe:
          httpGet:
            port: 3030
            path: /api/flux/v6/identity.pub
          initialDelaySeconds: 5
          timeoutSeconds: 5
        readinessProbe:
          httpGet:
            port: 3030
            path: /api/flux/v6/identity.pub
          initialDelaySeconds: 5
          timeoutSeconds: 5
        volumeMounts:
        - name: git-key
          mountPath: /etc/fluxd/ssh
          readOnly: true
        - name: git-keygen
          mountPath: /var/fluxd/keygen
        args:
        - --memcached-service=
        - --ssh-keygen-dir=/var/fluxd/keygen
        - [email protected]:foobar/kubernetes
        - --git-path=staging
        - --git-label=flux-staging
        - --git-ci-skip
        - --connect=ws://127.0.0.1:3032
        - --registry-ecr-region=us-west-1,us-west-2
        - --registry-require=ecr
        - --sync-garbage-collection

Expected behavior

Version 1.20.0 of flux should run normally as expected.

Logs

ts=2020-07-13T21:10:36.084739153Z caller=main.go:259 version=1.20.0
ts=2020-07-13T21:10:36.084794615Z caller=main.go:412 msg="using kube config: \"/root/.kube/config\" to connect to the cluster"
ts=2020-07-13T21:10:36.113027449Z caller=main.go:492 component=cluster identity=/etc/fluxd/ssh/identity
ts=2020-07-13T21:10:36.113069413Z caller=main.go:493 component=cluster identity.pub="ssh-rsa foobar"
ts=2020-07-13T21:10:36.113140189Z caller=main.go:498 host=https://100.64.0.1:443 version=kubernetes-v1.16.10
ts=2020-07-13T21:10:36.113216873Z caller=main.go:510 kubectl=/usr/local/bin/kubectl
ts=2020-07-13T21:10:36.113854136Z caller=main.go:527 ping=true
ts=2020-07-13T21:10:56.4261769Z caller=aws.go:117 component=aws info="restricting ECR registry scans" regions="[us-west-1 us-west-2]" include-ids=[] exclude-ids="[602401143452 918309763551]"
ts=2020-07-13T21:10:56.427819718Z caller=main.go:666 url=ssh://[email protected]/foobar/kubernetes user="Weave Flux" [email protected] signing-key= verify-signatures-mode=none sync-tag=flux-staging state=git readonly=false registry-disable-scanning=false notes-ref=flux-staging set-author=false git-secret=false sops=false
ts=2020-07-13T21:10:56.427886137Z caller=main.go:751 component=upstream URL=ws://127.0.0.1:3032
ts=2020-07-13T21:10:56.428414956Z caller=main.go:795 addr=:3030
ts=2020-07-13T21:10:56.429732472Z caller=upstream.go:133 component=upstream connecting=true
ts=2020-07-13T21:10:56.440429651Z caller=upstream.go:147 component=upstream connected=true
ts=2020-07-13T21:10:56.440660827Z caller=images.go:17 component=sync-loop msg="polling for new images for automated workloads"
ts=2020-07-13T21:10:56.440691559Z caller=images.go:27 component=sync-loop msg="no automated workloads"
ts=2020-07-13T21:10:56.440744694Z caller=loop.go:108 component=sync-loop err="loading last-synced resources: git repo not ready: git repo has not been cloned yet"
ts=2020-07-13T21:10:56.528869401Z caller=aws.go:212 component=aws info="attempting to refresh auth tokens" region=us-west-1 account-ids=1234
ts=2020-07-13T21:10:56.849358223Z caller=checkpoint.go:24 component=checkpoint msg="up to date" latest=1.20.0
ts=2020-07-13T21:11:07.826854457Z caller=loop.go:134 component=sync-loop event=refreshed url=ssh://[email protected]/foobar/kubernetes branch=master HEAD=b5e0cb1c1df856abcb09c05717221e82c2c24ab0
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x176c94f]

goroutine 104 [running]:
github.com/fluxcd/flux/pkg/cluster/kubernetes/resource.Load.func1(0xc002522030, 0x22, 0x0, 0x0, 0x20f5120, 0xc0024f4f90, 0x0, 0xc0024f4180)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/cluster/kubernetes/resource/load.go:32 +0x6f
path/filepath.Walk(0xc002522030, 0x22, 0xc0004bf6b0, 0x0, 0x0)
	/usr/local/go/src/path/filepath/path.go:402 +0x6a
github.com/fluxcd/flux/pkg/cluster/kubernetes/resource.Load(0xc0024725c0, 0x1a, 0xc001bb8f60, 0x1, 0x1, 0xc001bb8f00, 0xc0004e7020, 0xc0024725c0, 0xc0004bf790)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/cluster/kubernetes/resource/load.go:31 +0x19b
github.com/fluxcd/flux/pkg/cluster/kubernetes.(*manifests).LoadManifests(0xc0004e7020, 0xc0024725c0, 0x1a, 0xc001bb8f60, 0x1, 0x1, 0x42e0aa, 0x0, 0xc001bb7d40)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/cluster/kubernetes/manifests.go:122 +0x67
github.com/fluxcd/flux/pkg/manifests.(*rawFiles).GetAllResourcesByID(0xc001c16840, 0x213dda0, 0xc000042070, 0xc002402f60, 0x28, 0x21257a0)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/manifests/rawfiles.go:96 +0x60
github.com/fluxcd/flux/pkg/daemon.(*Daemon).getLastResources(0xc00017f680, 0x213dda0, 0xc000042070, 0x21256a0, 0xc000366a80, 0x0, 0x0, 0x0)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/daemon/sync.go:140 +0x176
github.com/fluxcd/flux/pkg/daemon.(*Daemon).Sync(0xc00017f680, 0x213dda0, 0xc000042070, 0x314a5f4a, 0xed69ec4eb, 0x0, 0xc002402e70, 0x28, 0x21256a0, 0xc000366a80, ...)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/daemon/sync.go:49 +0x82
github.com/fluxcd/flux/pkg/daemon.(*Daemon).Loop(0xc00017f680, 0xc000084240, 0xc000043460, 0x20f2f20, 0xc000675b00)
	/home/circleci/go/src/github.com/fluxcd/flux/pkg/daemon/loop.go:103 +0x525
created by main.main
	/home/circleci/go/src/github.com/fluxcd/flux/cmd/fluxd/main.go:777 +0x5990

Additional context

• Flux version: 1.20.0
• Kubernetes version: 1.16.10
• Git provider: Github
• Container registry provider: AWS ECR