An example python script to reroute unassigned shards to NODE_NAME node thus recovering from the red cluster status

reroute.py

#!/usr/bin/env python3
#
# An example python script to reroute unassigned shards to NODE_NAME node,
# thus recovering from the red cluster status
#

# pip install requests before using requests
import requests
import json

HOSTNAME="your.elasticsearch.host.com" # hostname
NODE_NAME="node001" # node to reroute to 
PORT=9200 # port number

def reroute(index, shard):
  payload = { "commands": [{ "allocate_empty_primary": { "index": index, "shard": shard, "node": NODE_NAME, "accept_data_loss": "true" } }] }
  res = requests.post("http://" + HOSTNAME + ":" + str(PORT) + "/_cluster/reroute", data=json.dumps(payload), headers={'Content-Type': 'application/json'})
  print(res.text)
  pass

res = requests.post("http://" + HOSTNAME + ":" + str(PORT) + "/_flush/synced", headers={'Content-Type': 'application/json'})
j = res.json()

for field in j:
  if j[field]["failed"] != 0 and field != "_shards":
    for item in j[field]["failures"]:
      reroute(field, item["shard"])