ArgoCDでGitHubのレポジトリを追加するときに、knownhosts: key mismatchエラーが発生するときの対処方法

# エラー内容

```
FATA[0007] rpc error: code = Unknown desc = ssh: handshake failed: knownhosts: key mismatch
FATA[0000] rpc error: code = FailedPrecondition desc = error creating SSH agent: "SSH agent requested but SSH_AUTH_SOCK not-specified"
```

# 対処方法

ArgoCDのHelmチャートのバージョンが3.26.8で発生します。昨日(2021/11/17)リリースされた[argo-cd 3.26.9 · argoproj/argo](https://artifacthub.io/packages/helm/argo/argo-cd/3.26.9)に更新すると解消します。

もしくは、argocd名前空間にある、`argocd-ssh-known-hosts-cm` というConfigMapの内容を更新する解消します。下記はConfigMap全文です。

```yaml:argocd-ssh-known-hosts-cm

apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    app.kubernetes.io/name: argocd-ssh-known-hosts-cm
    app.kubernetes.io/part-of: argocd
  name: argocd-ssh-known-hosts-cm
data:
  ssh_known_hosts: |
    bitbucket.org ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
    github.com ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq2A7hRGmdnm9tUDbO9IDSwBK6TbQa+PXYPCPy6rbTrTtw7PHkccKrpp0yVhp5HdEIcKr6pLlVDBfOLX9QUsyCOV0wzfjIJNlGEYsdlLJizHhbn2mUjvSAHQqZETYP81eFzLQNnPHt4EVVUh7VfDESU84KezmD5QlWpXLmvU31/yMf+Se8xhHTvKSCZIFImWwoG6mbUoWf9nzpIoaSjB+weqqUUmpaaasXVal72J+UX2B+2RPW3RcT0eOzQgqlJL3RKrTJvdsjE3JEAvGq3lGHSZXy28G3skua2SmVi/w4yCE6gbODqnTWlg7+wC604ydGXA8VJiS5ap43JXiUFFAaQ==
    gitlab.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFSMqzJeV9rUzU4kWitGjeR4PWSa29SPqJ1fVkhtj3Hw9xjLVXVYrU9QlYWrOLXBpQ6KWjbjTDTdDkoohFzgbEY=
    gitlab.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAfuCHKVTjquxvt6CM6tdG4SLp1Btn/nOeHHE5UOzRdf
    gitlab.com ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCsj2bNKTBSpIYDEGk9KxsGh3mySTRgMtXL583qmBpzeQ+jqCMRgBqB98u3z++J1sKlXHWfM9dyhSevkMwSbhoR8XIq/U0tCNyokEi/ueaBMCvbcTHhO7FcwzY92WK4Yt0aGROY5qX2UKSeOvuP4D6TPqKF1onrSzH9bx9XUf2lEdWT/ia1NEKjunUqu1xOB/StKDHMoX4/OKyIzuS0q/T1zOATthvasJFoPrAjkohTyaDUz2LN5JoH839hViyEG82yB+MjcFV5MU3N1l1QL3cVUCh93xSaua1N85qivl+siMkPGbO5xR/En4iEY6K2XPASUEMaieWVNTRCtJ4S8H+9
    ssh.dev.azure.com ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7Hr1oTWqNqOlzGJOfGJ4NakVyIzf1rXYd4d7wo6jBlkLvCA4odBlL0mDUyZ0/QUfTTqeu+tm22gOsv+VrVTMk6vwRU75gY/y9ut5Mb3bR5BV58dKXyq9A9UeB5Cakehn5Zgm6x1mKoVyf+FFn26iYqXJRgzIZZcZ5V6hrE0Qg39kZm4az48o0AUbf6Sp4SLdvnuMa2sVNwHBboS7EJkm57XQPVU3/QpyNLHbWDdzwtrlS+ez30S3AdYhLKEOxAG8weOnyrtLJAUen9mTkol8oII1edf7mWWbWVf0nBmly21+nZcmCTISQBtdcyPaEno7fFQMDD26/s0lfKob4Kw8H
    vs-ssh.visualstudio.com ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7Hr1oTWqNqOlzGJOfGJ4NakVyIzf1rXYd4d7wo6jBlkLvCA4odBlL0mDUyZ0/QUfTTqeu+tm22gOsv+VrVTMk6vwRU75gY/y9ut5Mb3bR5BV58dKXyq9A9UeB5Cakehn5Zgm6x1mKoVyf+FFn26iYqXJRgzIZZcZ5V6hrE0Qg39kZm4az48o0AUbf6Sp4SLdvnuMa2sVNwHBboS7EJkm57XQPVU3/QpyNLHbWDdzwtrlS+ez30S3AdYhLKEOxAG8weOnyrtLJAUen9mTkol8oII1edf7mWWbWVf0nBmly21+nZcmCTISQBtdcyPaEno7fFQMDD26/s0lfKob4Kw8H
    github.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=
    github.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOMqqnkVzrm0SdG6UOoqKLsabgH5C9okWi0dh2l9GKJl
```

from: [argo-cd/argocd-ssh-known-hosts-cm.yaml at master · argoproj/argo-cd](https://github.com/argoproj/argo-cd/blob/master/docs/operator-manual/argocd-ssh-known-hosts-cm.yaml)