带 Kubernetes 的 jsonpath 中的空方括号是什么意思？

Question

以下kubectl表达式returns镜像版本：

kubectl get po nginx -o jsonpath='{.spec.containers[].image}{"\n"}'

但是“[]”究竟表示什么？我知道它说图像是容器的子容器，容器是规范的子容器，但为什么 empty 方括号？

Answer 1

{.spec.containers} 将 return 一个数组。使用空方括号意味着 所需的值是一个数组。

您可以通过以下运行验证这一点，查询的输出是一个数组：

 kubectl get po mongo  -o jsonpath='{.spec.containers}{"\n"}'
[{"image":"mongo","imagePullPolicy":"Always","name":"mongo","ports":[{"containerPort":27107,"protocol":"TCP"}],"resources":{},"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File","volumeMounts":[{"mountPath":"/var/run/secrets/kubernetes.io/serviceaccount","name":"default-token-c949d","readOnly":true}]},{"image":"nginx","imagePullPolicy":"Always","name":"nginx","ports":[{"containerPort":80,"protocol":"TCP"}],"resources":{},"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File","volumeMounts":[{"mountPath":"/var/run/secrets/kubernetes.io/serviceaccount","name":"default-token-c949d","readOnly":true}]}]

当与 [] 一起使用时，我们希望 .spec.containers 的输出为数组并已对其进行处理：

kubectl get po mongo  -o jsonpath='{.spec.containers[]}{"\n"}'
{"image":"mongo","imagePullPolicy":"Always","name":"mongo","ports":[{"containerPort":27107,"protocol":"TCP"}],"resources":{},"terminationMessagePath":"/dev/termination-log","terminationMessagePolicy":"File","volumeMounts":[{"mountPath":"/var/run/secrets/kubernetes.io/serviceaccount","name":"default-token-c949d","readOnly":true}]}

带 Kubernetes 的 jsonpath 中的空方括号是什么意思？

What does empty square bracket mean in jsonpath with Kubernetes?

kubernetes

kubectl

jsonpath