The first script ensures your Sidekiq instances would act properly on each application deployment:

commands:
  create_post_dir:
    command: "mkdir -p /opt/elasticbeanstalk/hooks/appdeploy/post"
    ignoreErrors: true
files:
  "/opt/elasticbeanstalk/hooks/appdeploy/post/50_restart_sidekiq.sh":
    mode: "000755"
    owner: root
    group: root
    content: |
      #!/usr/bin/env bash
      . /opt/elasticbeanstalk/support/envvars

      EB_APP_DEPLOY_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k app_deploy_dir)
      EB_APP_PID_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k app_pid_dir)
      EB_APP_USER=$(/opt/elasticbeanstalk/bin/get-config container -k app_user)
      EB_SCRIPT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k script_dir)
      EB_SUPPORT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k support_dir)

      . $EB_SUPPORT_DIR/envvars
      . $EB_SCRIPT_DIR/use-app-ruby.sh

      SIDEKIQ_PID=$EB_APP_PID_DIR/sidekiq.pid
      SIDEKIQ_CONFIG=$EB_APP_DEPLOY_DIR/config/sidekiq.yml
      SIDEKIQ_LOG=$EB_APP_DEPLOY_DIR/log/sidekiq.log

      cd $EB_APP_DEPLOY_DIR

      if [ -f $SIDEKIQ_PID ]
      then
        su -s /bin/bash -c "kill -TERM `cat $SIDEKIQ_PID`" $EB_APP_USER
        su -s /bin/bash -c "rm -rf $SIDEKIQ_PID" $EB_APP_USER
      fi

      . /opt/elasticbeanstalk/support/envvars.d/sysenv

      sleep 10

      su -s /bin/bash -c "bundle exec sidekiq MALLOC_ARENA_MAX = 2 \
        -e $RACK_ENV \
        -P $SIDEKIQ_PID \
        -C $SIDEKIQ_CONFIG \
        -L $SIDEKIQ_LOG \
        -d" $EB_APP_USER

  "/opt/elasticbeanstalk/hooks/appdeploy/pre/03_mute_sidekiq.sh":
    mode: "000755"
    owner: root
    group: root
    content: |
      #!/usr/bin/env bash
      . /opt/elasticbeanstalk/support/envvars

      EB_APP_USER=$(/opt/elasticbeanstalk/bin/get-config container -k app_user)
      EB_SCRIPT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k script_dir)
      EB_SUPPORT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k support_dir)

      . $EB_SUPPORT_DIR/envvars
      . $EB_SCRIPT_DIR/use-app-ruby.sh

      SIDEKIQ_PID=$EB_APP_PID_DIR/sidekiq.pid
      if [ -f $SIDEKIQ_PID ]
      then
        su -s /bin/bash -c "kill -USR1 `cat $SIDEKIQ_PID`" $EB_APP_USER
      fi

The Second script is optional. You should apply it if your Sidekiq processes tend to memory bloating. It can be noticeable i.e. if your jobs process large files or initialize thousands of ActiveRecord objects each. In such situation your Sidekiq workers are constantly consuming more memory. In this configuration, monit script will restart them if its memory usage stays above 20%:

packages:
  yum:
    monit: []
files:
  "/etc/monit.d/sidekiq":
    mode: "000644"
    owner: root
    group: root
    content: |
      check process sidekiq
        with pidfile /var/app/containerfiles/pids/sidekiq.pid every 2 cycles
        if memory usage > 20% then exec "/opt/elasticbeanstalk/hooks/appdeploy/post/50_restart_sidekiq.sh"
commands:
  remove_bak:
    command: "rm /etc/monit.d/sidekiq.bak"
    ignoreErrors: true
services:
  sysvinit:
    monit:
      ensureRunning: true
      enabled: true