Kubernetes - 从工作连接到 cassandra 到不同的 pod

Question

当我尝试执行以下命令时

["/bin/sh", "-c", "cqlsh cassandra.my-namespace.svc.cluster.local -f /path/to/schema.cql"]

从我的工作中，我收到以下错误:

Traceback (most recent call last):
  File "/usr/bin/cqlsh.py", line 2443, in <module>
    main(*read_options(sys.argv[1:], os.environ))
  File "/usr/bin/cqlsh.py", line 2421, in main
    encoding=options.encoding)
  File "/usr/bin/cqlsh.py", line 485, in __init__
    load_balancing_policy=WhiteListRoundRobinPolicy([self.hostname]),
  File "/usr/share/cassandra/lib/cassandra-driver-internal-only-3.11.0-bb96859b.zip/cassandra-driver-3.11.0-bb96859b/cassandra/policies.py", line 417, in __init__
socket.gaierror: [Errno -2] Name or service not known

我的工作被定义为 Helm Hook 与 post-install注解。我的 Cassandra Pod 是使用 StatefulSet 定义的。

kind: StatefulSet
metadata:
  name: cassandra
spec:
  serviceName: cassandra
  replicas: 1
  template:
    metadata:
      labels:
        app: cassandra
    spec:
      containers:
        - name: cassandra
          image: cassandra:3
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 7000
              name: intra-node
            - containerPort: 7001
              name: tls-intra-node
            - containerPort: 7199
              name: jmx
            - containerPort: 9042
              name: cql
          env:
            - name: CASSANDRA_SEEDS
              value: cassandra-0.cassandra.default.svc.cluster.local
            - name: MAX_HEAP_SIZE
              value: 256M
            - name: HEAP_NEWSIZE
              value: 100M
            - name: CASSANDRA_CLUSTER_NAME
              value: "Cassandra"
            - name: CASSANDRA_DC
              value: "DC1"
            - name: CASSANDRA_RACK
              value: "Rack1"
            - name: CASSANDRA_ENDPOINT_SNITCH
              value: GossipingPropertyFileSnitch
          volumeMounts:
            - name: cassandra-data
              mountPath: /var/lib/cassandra/data
  volumeClaimTemplates:
    - metadata:
        name: cassandra-data
        annotations:  # comment line if you want to use a StorageClass
          # or specify which StorageClass
          volume.beta.kubernetes.io/storage-class: ""   # comment line if you
          # want to use a StorageClass or specify which StorageClass
      spec:
        accessModes: ["ReadWriteOnce"]
        resources:
          requests:
            storage: 1Gi

这是我的服务:

kind: Service
metadata:
  labels:
    app: cassandra
  name: cassandra
spec:
  clusterIP: None
  ports:
    - port: 9042
  selector
    app: cassandra

当我运行 cqlsh从容器手动命令，一切正常。不幸的是，自动化解决方案引发了上述错误。
我在服务配置中遗漏了什么吗？我认为自从我从 Job 创建的 Pod 连接到服务后，它应该可以工作。
编辑:
工作看起来像这样:

apiVersion: batch/v1
kind: Job
metadata:
  name: init-db
spec:
  template:
    metadata: 
      name: init-db
      annotations: 
        "helm.sh/hooks": postn-install
    spec:
      containers:
      - name: cqlsh
        image: <cassandra-image>
        command: ["/bin/sh", "-c", "cqlsh cassandra.my-namespace.svc.cluster.local -f /path/to/schema.cql"]
        volumeMounts:
        - name: cass-init
          mountPath: /etc/config
    volumes:
      ...

这是 etc/resolv.conf 的输出:

nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndtos:5

Answer 1

您发布的错误表明无论您在何处运行 cqlsh 命令，它都无法解析服务名称。
根据您的 k8s 集群的配置方式和作业运行的位置(在同一个 k8s 集群内或外部)，您需要使用 Ingress 公开对 pod 的访问权限。或 NodePort .
Aleš Nosek 在 his blog post here 中对如何访问 pod 进行了很好的解释。 .干杯!