How to use boto3 waiters to take snapshot from big RDS instances - amazon-web-services

Question

I started migrating my code to boto 3 and one nice addition I noticed are the waiters.
I want to create a snapshot from a db instance and I want to check for it's availability before I resume with my code.
My approach is the following:
# Notice: Step : Check snapshot availability [1st account - Oregon]
print "--- Check snapshot availability [1st account - Oregon] ---"
new_snap = client1.describe_db_snapshots(DBSnapshotIdentifier=new_snapshot_name)['DBSnapshots'][0]
# print pprint.pprint(new_snap) #debug
waiter = client1.get_waiter('db_snapshot_completed')
print "Manual snapshot is -pending-"
sleep(60)
waiter.wait(
DBSnapshotIdentifier = new_snapshot_name,
IncludeShared = True,
IncludePublic = False
)
print "OK. Manual snapshot is -available-"
,but the documentation says that it polls the status every 15 seconds for 40 times. That is 10 minutes. Yet, a rather big DB will need more than that .
How could I use the waiter to alleviate for that?

Answer 1

Waiters have configuration parameters'delay' and 'max_attempts'
like this :
waiter = rds_client.get_waiter('db_instance_available')
print( "waiter delay: " + str(waiter.config.delay) )
waiter.py on github

Answer 2

You could do it without the waiter if you like.
From the documentation for that waiter:
Polls RDS.Client.describe_db_snapshots() every 15 seconds until a successful state is reached. An error is returned after 40 failed checks.
Basically that means it does the following:
RDS = boto3.client('rds')
RDS.describe_db_snapshots()
You can just run that but filter to your snapshot id, here is the syntax.http://boto3.readthedocs.io/en/latest/reference/services/rds.html#RDS.Client.describe_db_snapshots
response = client.describe_db_snapshots(
DBInstanceIdentifier='string',
DBSnapshotIdentifier='string',
SnapshotType='string',
Filters=[
{
'Name': 'string',
'Values': [
'string',
]
},
],
MaxRecords=123,
Marker='string',
IncludeShared=True|False,
IncludePublic=True|False
)
This will end up looking something like this:
snapshot_description = RDS.describe_db_snapshots(DBSnapshotIdentifier='YOURIDHERE')
then you can just loop until that returns a snapshot which is available. So here is a very rough idea.
import boto3
import time
RDS = boto3.client('rds')
RDS.describe_db_snapshots()
snapshot_description = RDS.describe_db_snapshots(DBSnapshotIdentifier='YOURIDHERE')
while snapshot_description['DBSnapshots'][0]['Status'] != 'available' :
print("still waiting")
time.sleep(15)
snapshot_description = RDS.describe_db_snapshots(DBSnapshotIdentifier='YOURIDHERE')

Answer 3

I think the other answer alluded to this solution but here it is expressly.
[snip]
...
# Create your waiter
waiter_db_snapshot = client1.get_waiter('db_snapshot_completed')
# Increase the max number of tries as appropriate
waiter_db_snapshot.config.max_attempts = 120
# Add a 60 second delay between attempts
waiter_db_snapshot.config.delay = 60
print "Manual snapshot is -pending-"
....
[snip]