ES rollover lookback: do not throw exception on no indices to remove from alias

[jkandasa]

Describe the bug
ES rollover lookback pod crashes on no indices to remove from alias

Expected behavior
Should print the message and exist as normal

Version (please complete the following information):

• OS: linux, OCP 4.9
• Jaeger version: 1.26
• Deployment: OpenShift 4.9

Config

apiVersion: jaegertracing.io/v1
kind: Jaeger
metadata:
  name: es-rollover
spec:
  ingress:
    security: none
  strategy: production
  storage:
    esIndexCleaner:
      enabled: false
      schedule: "*/2 * * * *"
      numberOfDays: 0
    esRollover:
      schedule: "*/5 * * * *"
      conditions: '{"max_age":"3m"}'
      readTTL: 1h
    type: elasticsearch
    options:
      es.use-aliases: true
    elasticsearch:
      nodeCount: 1
      storage:
        storageClassName: "standard"
        size: "5G"
      resources:
        requests:
          memory: "1Gi"
          cpu: "510m"
        limits:
          memory: "1Gi"

error:

$ oc get pods
NAME                                                        READY   STATUS             RESTARTS       AGE
elasticsearch-cdm-esrolloveresrollover-1-8556865546-mr5jf   2/2     Running            0              22m
es-rollover-collector-755c4c68d8-ft74p                      1/1     Running            0              21m
es-rollover-es-lookback-27263920--1-7mq8j                   0/1     CrashLoopBackOff   5 (107s ago)   5m1s
es-rollover-es-rollover-27263915--1-x9kn2                   0/1     Completed          0              11m
es-rollover-es-rollover-27263920--1-8psrh                   0/1     Completed          0              6m32s
es-rollover-es-rollover-27263925--1-jbhkl                   0/1     Completed          0              92s
es-rollover-es-rollover-create-mapping--1-g292k             0/1     Completed          0              21m
es-rollover-query-77f96f79ff-pc8zj                          2/2     Running            0              21m

Error: no indices to remove from alias jaeger-span-read
Usage:
  jaeger-es-rollover lookback http://HOSTNAME:PORT [flags]

Flags:
  -h, --help             help for lookback
      --unit string      used with lookback to remove indices from read alias e.g, days, weeks, months, years (default "days")
      --unit-count int   count of UNITs (default 1)

Global Flags:
      --archive                     Handle archive indices
      --es.ilm-policy-name string   The name of the ILM policy to use if ILM is active (default "jaeger-ilm-policy")
      --es.password string          The password required by storage
      --es.tls.ca string            Path to a TLS CA (Certification Authority) file used to verify the remote server(s) (by default will use the system truststore)
      --es.tls.cert string          Path to a TLS Certificate file, used to identify this process to the remote server(s)
      --es.tls.enabled              Enable TLS when talking to the remote server(s)
      --es.tls.key string           Path to a TLS Private Key file, used to identify this process to the remote server(s)
      --es.tls.server-name string   Override the TLS server name we expect in the certificate of the remote server(s)
      --es.tls.skip-host-verify     (insecure) Skip server's certificate chain and host name verification
      --es.use-ilm                  Use ILM to manage jaeger indices
      --es.username string          The username required by storage
      --index-prefix string         Index prefix
      --timeout int                 Number of seconds to wait for master node response (default 120)