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Miscellaneous

Specifying ImagePullSecrets​

By default, Hive on MR3 does not use ImagePullSecrets when downloading Docker images. The user can also use an existing ImagePullSecret in two steps.

First add a new field spec.template.spec.imagePullSecrets.name in hive.yaml:

vi yaml/hive.yaml

spec:
  template:
    spec:
      imagePullSecrets:
      - name: myregistrykey

Alternatively the user may add a new field imagePullSecrets in hive-service-account.yaml.

Then specify the same secret in the configuration key mr3.k8s.pod.image.pull.secrets in conf/mr3-site.xml.

vi conf/mr3-site.xml

<property>
  <name>mr3.k8s.pod.image.pull.secrets</name>
  <value>myregistrykey</value>
</property>

(Alternatively the user may add a new field imagePullSecrets in master-service-account.yaml and worker-service-account.yaml.)

Similarly the user should update other YAML files (such as metastore.yaml) in order to use an existing ImagePullSecret.

Liveness and readiness probes​

The liveness and readiness probes of HiveServer2 performs TPC checks on the port for the default mode.

vi yaml/hive.yaml

        readinessProbe:
          tcpSocket:
            port: 9852
        livenessProbe:
          tcpSocket:
            port: 9852

The user can also use HTTP checks, but only if SSL is disabled.

vi yaml/hive.yaml

        readinessProbe:
          httpGet:
            path: /cliservice
            port: 10001
        livenessProbe:
          httpGet:
            path: /cliservice
            port: 10001

Setting the time for waiting when recovering from a DAGAppMaster failure​

If a DAGAppMaster Pod fails and the user submits a new query, HiveServer2 tries to connect to the non-existent DAGAppMaster at least twice and up to three times:

  1. to acknowledge the completion of previous queries, if any;
  2. to get an estimate number of Tasks for the new query;
  3. to get the current status of DAGAppMaster.

In each step, HiveServer2 makes as many attempts as specified by the configuration key ipc.client.connect.max.retries.on.timeouts in conf/core-site.xml, where each attempt takes 20 seconds. By default, ipc.client.connect.max.retries.on.timeouts is set to 3, so HiveServer2 spends up to 3 * 20 seconds * 3 times = 180 seconds trying to recover from a DAGAppMaster failure.