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Incorrect liveness probe for Redis not failing

I have configured a liveness probe for my Redis instances that makes sure that the Redis is able to retrieve keys for it to be able to be called ‘alive’.

  livenessProbe:
    initialDelaySeconds: 20
    periodSeconds: 10
    exec:
      command:
        {{- include "liveness_probe" . | nindent 16 }}

_liveness.tpl

{{/* Liveness probe script. */}}
{{- define "liveness_probe" -}}

- "redis-cli"
- "set"
- "liveness_test_key"
- ""SUCCESS""
- "&&"
- "redis-cli"
- "get"
- "liveness_test_key"
- "|"
- "awk"
- "'$1 != "SUCCESS" {exit 1}'"
{{- end }}

The pod is able to start after doing the change. However, I would like to make sure that the probe is working as expected. For that I just added a delete command before the get command.

{{/* Liveness probe script. */}}
{{- define "liveness_probe" -}}

- "redis-cli"
- "set"
- "liveness_test_key"
- ""SUCCESS""
- "&&"
- "redis-cli"
- "del"
- "liveness_test_key"
- "&&"
- "redis-cli"
- "get"
- "liveness_test_key"
- "|"
- "awk"
- "'$1 != "SUCCESS" {exit 1}'"
{{- end }}

I get the expected exit codes when I execute this command directly in my command prompt.

But the thing is that my pod is still able to start.

Is the liveness probe command I am using okay? If so, how do I verify this?

Tags:

2

Answers


  1. 0

    I think you’re confusing livenessProbewith readinessProbe. livenessProbe tells kubernetes to restart your pod if your command returns a non-zero exit code, this is executed after the period specified in initialDelaySeconds: 20

    Whereas readinessProbe is what decides whether a pod is in Ready state to accept traffict or not.

      readinessProbe:
    initialDelaySeconds: 20
    periodSeconds: 10
    exec:
      command:
        {{- include "liveness_probe" . | nindent 16 }}

    They can also be used together if you need so.

    Please check this page from kubernetes documentation where they explain livenessProbe, readinessProbe and startupProbe

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  2. 0

    Try this for your liveness probe it is working fine and you can try the same in readinessProbe:

    apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: redis
  name: redis
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: redis
    spec:
      containers:
      - image: redis
        name: redis
        livenessProbe:
          exec:
            command:
            - sh
            - -c
            - |            
                #!/usr/bin/env bash -e
                #export REDISCLI_AUTH="$REDIS_PASSWORD"

                set_response=$(
                  redis-cli set liveness_test_key "SUCCESS"
                )

                del_response=$(
                    redis-cli del liveness_test_key
                )

                response=$(
                  redis-cli get liveness_test_key
                )

                if [ "$response" != "SUCCESS" ] ; then
                  echo "Unable to get keys, something is wrong"
                  exit 1
                fi               

          initialDelaySeconds: 5
          periodSeconds: 5
          
status: {}

    You will need to edit these values in your template

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