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replica_set
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replica_set
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#!/usr/bin/env python3
import os
import time
import argparse
from pymongo import MongoClient
from pymongo.errors import OperationFailure, ServerSelectionTimeoutError
from dotenv import load_dotenv
load_dotenv()
load_dotenv(os.environ.get("LOCATION"))
load_dotenv(f'{os.environ.get("HA_NFS_DATA_DIRECTORY")}/config/.env', override=True)
MAINTENANCE_PASSWORD_ESCAPED = os.getenv("MAINTENANCE_PASSWORD_ESCAPED")
HA_CURRENT_NODE = os.environ["HA_CURRENT_NODE"]
REPLICA_SET_INITIALIZE_RETRY_COUNT = 3
def strtobool(val):
val = val.lower()
if val in ('y', 'yes', 't', 'true', 'on', '1'):
return 1
elif val in ('n', 'no', 'f', 'false', 'off', '0'):
return 0
else:
raise ValueError("invalid truth value %r" % (val,))
def create_client(connection_string, direct_connection=False):
print("Creating mongo client...")
client = MongoClient(connection_string, directConnection=direct_connection)
return client
def isRedHat():
try:
with open("/etc/redhat-release") as f:
content = f.readline()
if content.startswith("Red Hat"):
return True
else:
return False
except Exception as e:
return False
def create_replica_set(connection_string):
try:
client = create_client(connection_string, True)
config = {
"_id": "mongo_replica_set",
"members": [
{ "_id": 0, "host": f"{HA_CURRENT_NODE}:27017" },
]
}
print("Validating if replica set is already initialized...")
retry_count = 0
while retry_count < REPLICA_SET_INITIALIZE_RETRY_COUNT:
retry_count += 1
try:
replica_status = client.admin.command("replSetGetStatus")
if replica_status.get("ok") == 1.0:
print("The MongoDB Replica set is already initialized.")
exit(1)
except ServerSelectionTimeoutError as ex:
if retry_count == REPLICA_SET_INITIALIZE_RETRY_COUNT:
raise ex
time.sleep(30)
except OperationFailure as error:
if 'NotYetInitialized' in str(error):
break
raise error
print("Initializing MongoDB replica set...")
retry_count = 0
while retry_count < REPLICA_SET_INITIALIZE_RETRY_COUNT:
retry_count += 1
try:
_ = client.admin.command("replSetInitiate", config)
break
except ServerSelectionTimeoutError as ex:
if retry_count == REPLICA_SET_INITIALIZE_RETRY_COUNT:
raise ex
time.sleep(30)
print("Replica set initialized.")
retry = 30
wait_time = 30
settings_found = False
while True:
print("Waiting for migrations to be completed...")
time.sleep(5)
response = client.cte["settings"].find_one({})
if not response:
if not retry:
print("Unable to find settings collection in the database. Exiting...")
break
print("Unable to find settings collection in the database. Retrying...")
retry -= 1
time.sleep(wait_time)
continue
if not settings_found:
print("Settings collection found in database.")
settings_found = True
db_version = dict(response).get("databaseVersion", "")
if db_version == os.environ["INSTALL_VERSION"]:
print("Migrations completed.")
if isRedHat():
print("Execute this command in remaining nodes to form a cluster:\n > sudo ./start")
else:
print("Execute this command in remaining nodes to form a cluster:\n > ./start")
break
except OperationFailure as ex:
raise ex
finally:
client.close()
def join_replica_set(connection_string):
print("Adding new node to the MongoDB replica set...")
try:
client = create_client(connection_string)
config = client.admin.command('replSetGetConfig')
max_id = 1
for member in config['config']['members']:
if member['_id'] > max_id:
max_id = member['_id']
config['config']['members'].append({
'_id': max_id + 1,
'host': f'{HA_CURRENT_NODE}:27017'
})
config['config']['version'] += 1
_ = client.admin.command("replSetReconfig", config['config'])
print("The node is added to the MongoDB replica set.")
except OperationFailure as ex:
print("The node is already connected with the cluster.")
raise ex
finally:
client.close()
def update_connection_info(old_ip, new_ip):
with open(".env", "r") as env_file:
content = env_file.read()
content = content.replace(
f"HA_PRIMARY_NODE_IP={old_ip}",
f"HA_PRIMARY_NODE_IP={new_ip}"
)
with open(".env", "w+") as env_file:
env_file.write(content)
# Update shared .env file
env_location = f'{os.environ.get("HA_NFS_DATA_DIRECTORY")}/config/.env'
with open(env_location, "r") as env_file:
content = env_file.read()
content = content.replace(
f"HA_PRIMARY_NODE_IP={old_ip}",
f"HA_PRIMARY_NODE_IP={new_ip}"
)
with open(env_location, "w+") as env_file:
env_file.write(content)
def remove_replica_set(connection_string):
print("Removing node from the MongoDB replica set...")
try:
client = create_client(connection_string)
cluster_status = client.admin.command({'replSetGetStatus': 1})
if len(cluster_status["members"]) == 1:
print("This is the only node in the cluster. Stopping the services...")
if HA_CURRENT_NODE != os.environ["HA_PRIMARY_NODE_IP"]:
update_connection_info(os.environ['HA_PRIMARY_NODE_IP'], HA_CURRENT_NODE)
exit(3)
for member in cluster_status["members"]:
if member["stateStr"] == "PRIMARY" and member["name"] == f'{HA_CURRENT_NODE}:27017':
print("This is the primary node. Stepping down...")
client.admin.command("replSetStepDown", 60)
print("Step down initiated successfully.")
if HA_CURRENT_NODE == os.environ["HA_PRIMARY_NODE_IP"]:
cluster_status = client.admin.command({'replSetGetStatus': 1})
new_primary_ip = ""
for member in cluster_status["members"]:
if member["stateStr"] == "PRIMARY":
new_primary_ip = member["name"].split(":")[0]
# Update the local env file to change the primary node.
if new_primary_ip:
update_connection_info(os.environ['HA_PRIMARY_NODE_IP'], new_primary_ip)
config = client.admin.command('replSetGetConfig')
members = []
for member in config['config']['members']:
if member['host'] != f'{HA_CURRENT_NODE}:27017':
members.append(member)
config['config']['members'] = members
config['config']['version'] += 1
_ = client.admin.command("replSetReconfig", config['config'])
print("The MongoDB Replica set has been removed from the cluster.")
except ServerSelectionTimeoutError as ex:
print("The other MongoDB nodes are not reachable, stopping the services.")
exit(3)
except Exception as ex:
print("Error occured while removing node from the cluster.")
print(str(ex))
raise ex
finally:
client.close()
if __name__ == "__main__":
parser = argparse.ArgumentParser(
prog='./replica_set',
description='Initiate MongoDB replica set.',
epilog='For more info, please read the user guide.'
)
parser.add_argument('-i', '--initiate', type=lambda x:bool(strtobool(x)), nargs='?', const=True, default=False, help='Initiate MongoDB replica set with current node as a primary.')
parser.add_argument('-j', '--join', type=lambda x:bool(strtobool(x)), nargs='?', const=True, default=False, help='Add the current node to the replica set.')
parser.add_argument('-r', '--remove', type=lambda x:bool(strtobool(x)), nargs='?', const=True, default=False, help='Remove the current node from the replica set.')
args = parser.parse_args()
try:
# Create Mongo replica set
if args.initiate:
connection_string = f"mongodb://root:{MAINTENANCE_PASSWORD_ESCAPED}@{HA_CURRENT_NODE}:27017/admin"
create_replica_set(connection_string)
# Join the node to the Mongo replica set
elif args.join:
hostname = ",".join([f"{ip}:27017" for ip in os.environ["HA_IP_LIST"].split(",") if ip != HA_CURRENT_NODE])
connection_string = f"mongodb://root:{MAINTENANCE_PASSWORD_ESCAPED}@{hostname}/admin?replicaSet=mongo_replica_set"
join_replica_set(connection_string)
# Remove the node from the Mongo replica set
elif args.remove:
hostname = ",".join([f"{ip}:27017" for ip in os.environ["HA_IP_LIST"].split(",")])
connection_string = f"mongodb://root:{MAINTENANCE_PASSWORD_ESCAPED}@{hostname}/admin?replicaSet=mongo_replica_set"
remove_replica_set(connection_string)
else:
print("Please provide at least one option to run this script.")
except Exception as ex:
print(str(ex))
exit(1)
exit(0)