#!/usr/bin/env bash
set -e

es_server_prefix=elastic10
es_server_suffix=.eqiad.wmnet
first_server_index=1
nb_of_servers_in_cluster=47

# used to keep track on which server this script has already been executed
# this enables this script to be mostly idempotent, so that it can be
# relaunched as is in case of error
# WARN: needs to be changed manually
execution_id=ZplljWNP9hNobookM8fUhFuivkAKm8w3mVlQawXBg5c4JxzuEPcJcLgtY8ms0Pg

for i in $(seq -w ${first_server_index} ${nb_of_servers_in_cluster}); do
    hostname="${es_server_prefix}${i}"
    server="${es_server_prefix}${i}${es_server_suffix}"

    if ssh ${server} grep -q ${execution_id} /var/lib/elasticsearch/script_execution_id ; then
        echo "restart already executed on ${hostname}, skipping..."
        continue
    fi

    echo "disabling alerts for ${hostname}"
    ssh neon.wikimedia.org sudo icinga-downtime -h ${hostname} -d 1800 -r "restarting for config change - ${USER}"

    echo "disabling replication"
    until ssh ${server} es-tool stop-replication
    do
        echo "failed to stop replication, trying again"
    done

    echo "ready to start restart ${hostname}"

#    echo "rebooting ${hostname}"
#    ssh neodymium.eqiad.wmnet sudo salt ${server} system.reboot
#    For some reason, rebooting as above does not work, host never completes shutdown
    echo "You can now reboot ${server}"
    echo "Press [enter] when done"
    read

    echo "waiting for server to be up"
    until ssh ${server} true &> /dev/null; do
        echo -n .
        sleep 1
    done
    echo "server is up"

    echo "waiting for elasticsearch to be started"
    until ssh ${server} curl -s 127.0.0.1:9200/_cat/health; do
        echo -n '.'
        sleep 1
    done
    echo "elasticsearch is started"

    echo "enabling replication"
    until ssh ${server} es-tool start-replication
    do
        echo "failed to start replication, trying again"
    done

    echo "waiting for cluster recovery"
    ssh ${server} "until curl -s 127.0.0.1:9200/_cat/health | grep green; do echo -n .; sleep 10; done"
    echo "cluster is green"

    echo "creating file to keep track of script execution"
    ssh ${server} "echo ${execution_id} | sudo tee /var/lib/elasticsearch/script_execution_id"

    echo "Done for ${hostname}"
    echo "=============================================="
done

echo "Cluster restart completed"
echo "Cleaning up..."

for i in $(seq -w ${first_server_index} ${nb_of_servers_in_cluster}); do
    hostname="${es_server_prefix}${i}"
    server="${es_server_prefix}${i}${es_server_suffix}"

    ssh ${server} "sudo rm /var/lib/elasticsearch/script_execution_id"
done