How to recover elastic search shards

recover_shards.py

"""
Inspired by https://t37.net/how-to-fix-your-elasticsearch-cluster-stuck-in-initializing-shards-mode.html

3 node cluster, when 2 nodes have been terminated simultaneously

Not guaranteed to prevent data loss or fully recover lost data

"""
import requests
import json

HEALTHY_NODE = "10.65.15.5"

NEW_NODE_A = "10.65.14.5"
NEW_NODE_B = "10.65.13.5"

obj = requests.get("http://%s:9200/_cat/shards?format=json" % HEALTHY_NODE).json()
command_list = []

for item in obj:
    if item["state"] == "UNASSIGNED" and item["prirep"] == "p":
        if item["node"] == NEW_NODE_A:
            node = NEW_NODE_B"
        else:
            node = NEW_NODE_A
        command_list.append({
          "allocate" : {
              "index" : item["index"], 
              "shard" : item["shard"], 
              "node" : node, 
              "allow_primary" : True
          }
        })        

requests.post("http://%s:9200/_cluster/reroute" % HEALTHY_NODE, data=json.dumps({"commands" : command_list}))