在 Google 運算引擎上執行的 kubernetes pod 無法存取元資料服務

Question

我正在嘗試從 k8 pod 內部運行 google cloud python sdk，在 google 計算引擎上運行。 VM 附加了一個服務帳戶，該帳戶允許其存取機密管理器。我能夠從主機存取機密管理器，但是從 k8 pod 運行 python sdk 抱怨無法存取元資料服務

>>> secret_id = 'unskript_test'
>>> name = client.secret_path(project_id, secret_id)
>>> response = client.get_secret(request={"name": name})
Traceback (most recent call last):
  File "/opt/conda/lib/python3.7/site-packages/google/api_core/grpc_helpers.py", line 67, in error_remapped_callable
    return callable_(*args, **kwargs)
  File "/opt/conda/lib/python3.7/site-packages/grpc/_channel.py", line 946, in __call__
    return _end_unary_response_blocking(state, call, False, None)
  File "/opt/conda/lib/python3.7/site-packages/grpc/_channel.py", line 849, in _end_unary_response_blocking
    raise _InactiveRpcError(state)
grpc._channel._InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
    status = StatusCode.UNAVAILABLE
    details = "Getting metadata from plugin failed with error: Failed to retrieve http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true from the Google Compute Enginemetadata service. Compute Engine Metadata server unavailable"
    debug_error_string = "{"created":"@1630634901.103779641","description":"Getting metadata from plugin failed with error: Failed to retrieve http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true from the Google Compute Enginemetadata service. Compute Engine Metadata server unavailable","file":"src/core/lib/security/credentials/plugin/plugin_credentials.cc","file_line":90,"grpc_status":14}"
>

k8 pod 無法解析metadata.google.internal

jovyan@jovyan-25ca6c8c-157d-49e5-9366-f9d57fcb7a9f:~$ wget http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true
--2021-09-03 02:11:19--  http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true
Resolving metadata.google.internal (metadata.google.internal)... failed: Name or service not known.
wget: unable to resolve host address ‘metadata.google.internal’

不過樓主可以解決

ubuntu@gcp-test-proxy:~$ wget http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true
--2021-09-03 02:11:27--  http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/?recursive=true
Resolving metadata.google.internal (metadata.google.internal)... 169.254.169.254
Connecting to metadata.google.internal (metadata.google.internal)|169.254.169.254|:80... connected.
HTTP request sent, awaiting response... 403 Forbidden
2021-09-03 02:11:27 ERROR 403: Forbidden.

如何使 pod 解析metadata.google.internal？

Answer 1

這是由於 Kubernetes pod 無法將metadata.google.internalDNS 名稱解析為正確的 IP 所造成的。您的主機可能有一個條目/etc/hosts將該網域硬編碼為 IP：169.254.169.254。

您應該能夠透過修改 Pod 的/etc/hosts檔案來複製它。

請記住，這僅適用於在 GCP 上執行的虛擬機器。在外面，IP位址169.254.169.254只是另一個沒有特殊意義的IP位址。

編輯：剛剛檢查了我的一台 GCP 虛擬機器上的 /etc/hosts，這是我發現的內容：

$ cat /etc/hosts
127.0.0.1 localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
169.254.169.254 metadata.google.internal metadata

因此，只需嘗試將最後一行複製到您的 pod 中即可/etc/hosts。

Answer 2

問題在於 microk8s 沒有將主機等主機條目複製到 Pod。一旦我們轉移到 k3，問題就解決了