A generic toolkit for modeling capacity requirements in the cloud. Pricing information included in this repository are public prices.
NOTE: Netflix confidential information should never enter this repo. Please consider this repository public when making changes to it.
Run the tests:
# Test the capacity planner on included netflix models
$ tox -e py38
# Run a single test with a debugger attached if the test fails
$ .tox/py38/bin/pytest -n0 -k test_java_heap_heavy --pdb --pdbcls=IPython.terminal.debugger:Pdb
# Verify all type contracts
$ tox -e mypyRun IPython for interactively using the library:
tox -e dev -- ipython
Fire up ipython and let's capacity plan a Tier 1 (important to the product aka "prod") Cassandra database.
from service_capacity_modeling.interface import CapacityDesires
from service_capacity_modeling.interface import FixedInterval, Interval
from service_capacity_modeling.interface import QueryPattern, DataShape
db_desires = CapacityDesires(
# This service is important to the business, not critical (tier 0)
service_tier=1,
query_pattern=QueryPattern(
# Not sure exactly how much QPS we will do, but we think around
# 10,000 reads and 10,000 writes per second.
estimated_read_per_second=Interval(
low=1000, mid=10000, high=100000, confidence=0.9
),
estimated_write_per_second=Interval(
low=1000, mid=10000, high=100000, confidence=0.9
),
),
# Not sure how much data, but we think it'll be below 1 TiB
data_shape=DataShape(
estimated_state_size_gib=Interval(low=100, mid=100, high=1000, confidence=0.9),
),
)Now we can load up some models and do some capacity planning
from service_capacity_modeling.capacity_planner import planner
from service_capacity_modeling.models.org import netflix
import pprint
# Load up the Netflix capacity models
planner.register_group(netflix.models)
cap_plan = planner.plan(
model_name="org.netflix.cassandra",
region="us-east-1",
desires=db_desires,
# Simulate the possible requirements 512 times
simulations=512,
# Request 3 diverse hardware families to be returned
num_results=3,
)
# The range of requirements in hardware resources (CPU, RAM, Disk, etc ...)
requirements = cap_plan.requirements
# The ordered list of least regretful choices for the requirement
least_regret = cap_plan.least_regret
# Show the range of requirements for a single zone
pprint.pprint(requirements.zonal[0].dict(exclude_unset=True))
# Show our least regretful choices of hardware in least regret order
# So for example if we can buy the first set of computers we would prefer
# to do that but we might not have availability in that family in which
# case we'd buy the second one.
for choice in range(3):
num_clusters = len(least_regret[choice].candidate_clusters.zonal)
print(f"Our #{choice + 1} choice is {num_clusters} zones of:")
pprint.pprint(least_regret[choice].candidate_clusters.zonal[0].dict(exclude_unset=True))Note that we can customize more information given what we know about the use case, but each model (e.g. Cassandra) supplies reasonable defaults.
For example we can specify a lot more information
db_desires = CapacityDesires(
# This service is important to the business, not critical (tier 0)
service_tier=1,
query_pattern=QueryPattern(
# Not sure exactly how much QPS we will do, but we think around
# 50,000 reads and 45,000 writes per second with a rather narrow
# bound
estimated_read_per_second=Interval(
low=40_000, mid=50_000, high=60_000, confidence=0.9
),
estimated_write_per_second=Interval(
low=42_000, mid=45_000, high=50_000, confidence=0.9
),
# This use case might do some partition scan queries that are
# somewhat expensive, so we hint a rather expensive ON-CPU time
# that a read will consume on the entire cluster.
estimated_mean_read_latency_ms=Interval(
low=0.1, mid=4, high=20, confidence=0.9
),
# Writes at LOCAL_ONE are pretty cheap
estimated_mean_write_latency_ms=Interval(
low=0.1, mid=0.4, high=0.8, confidence=0.9
),
# We want single digit latency, note that this is not a p99 of 10ms
# but defines the interval where 98% of latency falls to be between
# 0.4 and 10 milliseconds. Think of:
# low = "the minimum reasonable latency"
# high = "the maximum reasonable latency"
# mid = "value between low and high such that I want my distribution
# to skew left or right"
read_latency_slo_ms=FixedInterval(
low=0.4, mid=4, high=10, confidence=0.98
),
write_latency_slo_ms=FixedInterval(
low=0.4, mid=4, high=10, confidence=0.98
)
),
# Not sure how much data, but we think it'll be below 1 TiB
data_shape=DataShape(
estimated_state_size_gib=Interval(low=100, mid=500, high=1000, confidence=0.9),
),
)In this example we tweak the QPS up, on CPU time of operations down and SLO down. This more closely approximates a caching workload
cache_desires = CapacityDesires(
service_tier=1,
query_pattern=QueryPattern(
# Not sure exactly how much QPS we will do, but we think around
# 10,000 reads and 10,000 writes per second.
estimated_read_per_second=Interval(
low=10_000, mid=100_000, high=1_000_000, confidence=0.9
),
estimated_write_per_second=Interval(
low=1_000, mid=20_000, high=100_000, confidence=0.9
),
# Memcache is consistently fast at queries
estimated_mean_read_latency_ms=Interval(
low=0.05, mid=0.2, high=0.4, confidence=0.9
),
estimated_mean_write_latency_ms=Interval(
low=0.05, mid=0.2, high=0.4, confidence=0.9
),
# Caches usually have tighter SLOs
read_latency_slo_ms=FixedInterval(
low=0.4, mid=0.5, high=5, confidence=0.98
),
write_latency_slo_ms=FixedInterval(
low=0.4, mid=0.5, high=5, confidence=0.98
)
),
# Not sure how much data, but we think it'll be below 1000
data_shape=DataShape(
estimated_state_size_gib=Interval(low=100, mid=200, high=500, confidence=0.9),
),
)
cache_cap_plan = planner.plan(
model_name="org.netflix.cassandra",
region="us-east-1",
desires=cache_desires,
allow_gp2=True,
)
requirement = cache_cap_plan.requirement
least_regret = cache_cap_plan.least_regretWe have a demo notebook in notebooks you can use to experiment. Start it with
tox -e notebook -- jupyter notebook notebooks/demo.ipynb
To contribute to this project:
- Make your change in a branch. Consider making a new model if you are making significant changes and registering it as a different name.
- Write a unit test using
pytestin thetestsfolder. - Ensure your tests pass (or debug them) with:
tox -e py38 -- -k test_<your_functionality> --pdb --pdbcls=IPython.terminal.debugger:Pdb
TODO