paasta: autoscaling at yelp
TRANSCRIPT
Nathan [email protected] / @nathanhandler
PaaSTAAutoscaling at Yelp
● Nathan Handler / @nathanhandler● Site Reliability Engineer at Yelp● PaaSTA Developer and Maintainer● Ubuntu/Debian GNU/Linux Developer● freenode IRC staff member
Who am I?
2
Yelp’s MissionConnecting people with great
local businesses.
3
Yelp StatsAs of Q3 2016
97M 3274%115M
● Monolithic Python application (~3M LoC)● Builds/deployments took a long time
○ Bottleneck on how often we can deploy● Mistakes are painful
○ Large impact○ Difficult to find○ Slow to fix
History
5
● Split features into different applications● Smaller services allowed for faster pushes● Easier to reason about issues● Able to scale services independently
Service Oriented Architecture v1
6
● Standalone application● Stateless● Separate git repository● Typically at Yelp:
○ HTTP API○ Python, Pyramid, uWSGI○ virtualenv
What is a service?
7
● Statically defined list of hosts to deploy a service on● Operations decides which hosts to deploy to● Monitoring manually configured in Nagios● Manual deployment system via rsync
Deploying Services v1
8
3x
2x
Does Not Scale
9
1x
3x
2x
Does Not Scale
10
1x
● Yelp's Platform as a Service● Builds, Deploys, Connects, and Monitors services● Glue around existing and established open source
tools
PaaSTA
11https://github.com/yelp/paasta#paasta on irc.freenode.net
12
PaaSTA Components
13
DockerRegistry
Developer
git push
git pull
git push
docker push
13
Marathon
Sensu
PaaSTA Components
14
Developer
git push
14
.├── Dockerfile├── htdocs│ ├── index.php│ └── status└── Makefile
15
A simple service
DOCKER_TAG ?= $(USER)-dev
test: @echo 'Unit testing'
itest: cook-image paasta local-run --healthcheck --service devops
cook-image: docker build -t $(DOCKER_TAG) .
16
$ cat Makefile
DOCKER_TAG ?= $(USER)-dev
test: @echo 'Unit testing'
itest: cook-image paasta local-run --healthcheck --service devops
cook-image: docker build -t $(DOCKER_TAG) .
17
$ cat Makefile
Containers: like lightweight VMsProvides a language (Dockerfile) for describing container imageReproducible builds (mostly)Provides software flexibility
18
Docker
docker.com
FROM ubuntu:xenialMAINTAINER Nathan Handler <[email protected]>
RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get -y install \ apache2 \ libapache2-mod-php
ENV APACHE_RUN_USER www-dataENV APACHE_RUN_GROUP www-dataENV APACHE_LOG_DIR /var/log/apache2ENV APACHE_LOCK_DIR /var/lock/apache2ENV APACHE_PID_FILE /var/run/apache2.pid
RUN rm -f /var/www/html/index.htmlCOPY htdocs /var/www/html/
CMD ["/usr/sbin/apache2", "-D", "FOREGROUND", "-C", "listen 8888"]EXPOSE 8888 19
$ cat Dockerfile
✓ yelpsoa-config directory for devops found in /nail/etc/services✓ deploy.yaml exists for a Jenkins pipeline✗ No 'security-check' entry was found in your deploy.yaml.Please add a security-check entry *AFTER* the itest entry in deploy.yamlso your docker image can be checked against known security vulnerabilities.More info: http://servicedocs.yelpcorp.com/docs/paasta_tools/cli/security_check.html✗ No 'performance-check' entry was found in your deploy.yaml.Please add a performance-check entry *AFTER* the security-check entry in deploy.yamlso your docker image can be checked for performance regressions.More info: http://servicedocs.yelpcorp.com/docs/paasta_tools/cli/performance_check.html✓ Jenkins build pipeline found✓ Git repo found in the expected location.✓ Found Dockerfile✓ A Makefile is present✓ The Makefile contains a tab character✓ The Makefile contains a docker tag✓ The Makefile responds to `make cook-image`✓ The Makefile responds to `make itest`✓ The Makefile responds to `make test`✓ Found marathon.yaml file.✓ All entries in deploy.yaml correspond to a marathon or chronos entry✓ All marathon instances have a corresponding deploy.yaml entry✓ monitoring.yaml found for Sensu monitoring✓ Your service uses Sensu and team 'nhandler' will get alerts.✓ Found smartstack.yaml file✓ Instance 'demo' of your service is using smartstack port 20973 and will be automatically load balanced✓ Successfully validated schema: marathon-nova-devc.yaml 20
$ paasta check
PaaSTA Components
21
DockerRegistry
Developer
git push
git pull
git push
docker push
21
---pipeline:- instancename: itest- instancename: push-to-registry- instancename: dev.everything
22
$ cat deploy.yaml
Jenkins Pipeline
23
paasta-nova-devc.demo-20160503T231914-deploypaasta-nova-devc.demo-20160503T234021-stoppaasta-nova-devc.demo-20160503T234202-start
24
$ git tag
Describe end goal, not pathHelps us achieve fault tolerance.
"Deploy 6de16ff2 to prod"vs.
"Commit 6de16ff2 should be running in prod"
Gas pedal vs. Cruise Control25
Declarative control
Description: A demo PaaSTA service for OSCON 2016External Link: http://conferences.oreilly.com/oscon/open-source-us/public/schedule/detail/49358Monitored By: team nhandlerRunbook: Please set a `runbook` field in your monitoring.yaml. Like "y/rb-mesos". Docs: https://trac.yelpcorp.com/wiki/HowToService/Monitoring/monitoring.yamlGit Repo: [email protected]:services/devopsJenkins Pipeline: https://jenkins.yelpcorp.com/view/services-devopsDeployed to the following clusters: - nova-devc (N/A)Smartstack endpoint(s): - http://169.254.255.254:20973 (demo)Dashboard(s): - https://uchiwa.yelpcorp.com/#/events?q=devops (Sensu Alerts)
26
$ paasta info
PaaSTA Components
27
DockerRegistry
Developer
git push
git pull
git push
docker push
27
Marathon
Mesos is an "SDK for distributed systems", not batteries-included.Requires a framework• Marathon• Chronos
Can run many frameworks on the same clusterSupports Docker as task executor
28
mesosphere.iomesos.apache.org
Scheduling: Mesos + Marathon
---main: cpus: 0.1 instances: 3 mem: 500
29
$ cat marathon-nova-devc.yaml
PaaSTA Components
30
DockerRegistry
Developer
git push
git pull
git push
docker push
30
Marathon
● Brutal: Stops old versions and starts the new version, without regard to safety.
● Upthendown: Brings up the new version of the service and waits until all instances are healthy before stopping the old versions.
● Downthenup: Stops any old versions and waits for them to die before starting the new version.
● Crossover: Starts the new version, and gradually kills instances of the old versions as new instances become healthy.
Bounce Strategies
31
32
Discovery in PaaSTA: Smartstack
mesosslave
box2client
nerve
HAProxy
synapse
box1service
nerve
mesosslave
synapse
HAProxy
ZooKeeperMetadataHTTP request
healthcheck
33
Latency Zones
SuperregionRegionHabitat
---demo: advertise: [region] discover: region proxy_port: 20973
34
$ cat smartstack.yaml
● Reduce/Eliminate Manual Scaling● Stop Overprovisioning● Save Money on our Infrastructure Bill● Increase Reliability
Why Autoscale?
35
Pipeline: https://jenkins.yelpcorp.com/view/services-devops
cluster: nova-devc instance: demo Git sha: 6de16ff2 State: Running - Desired state: Started Marathon: Healthy - up with (3/3) instances. Status: Running. Mesos: Healthy - (3/3) tasks in the TASK_RUNNING state. Smartstack: Name LastCheck LastChange Status useast1-devc - Healthy - in haproxy with (3/3) total backends UP in this namespace.
36
$ paasta status
Autoscaling Should Be Easy
37
---main: cpus: 0.1 instances: 3 mem: 500
38
$ cat marathon-nova-devc.yaml
---main: cpus: 0.1 min_instances: 3 max_instances: 5 mem: 500
39
$ cat marathon-nova-devc.yaml
Autoscaling Should Be Flexible
40
● mesos_cpu: Tries to use CPU usage to predict when to autoscale (Default)
● http: Makes a request on a HTTP endpoint on your service. Expects a JSON-formatted dictionary with a 'utilization' field containing a number 0-1
● uwsgi: Uses the percentage of non-idle workers as the utilization metric
Metrics Providers
41
● pid: Uses a PID controller to determine when to autoscale a service
● threshold: Autoscales when a service’s utilization exceeds beyond a certain threshold.
● bespoke: Allows a service author to implement their own autoscaling.
Decision Policies
42
---main: cpus: 0.1 min_instances: 3 max_instances: 12 mem: 500
autoscaling: metrics_provider: http endpoint: metrics.json decision_policy: threshold setpoint: 0.5
43
$ cat marathon-nova-devc.yaml
Autoscaling
44
● Examines all resources tracked by PaaSTA○ Scales based on the "worst" value
● Supports scaling pools independently● Supports a configurable target_utilization● Supports both ASGs and SFRs in AWS
Cluster Autoscaler
45
Cluster: mesosstageDashboards: Marathon RO: http://marathon.paasta-mesosstage.yelp/ Smartstack: http://paasta-mesosstage.yelp:3212 Chronos RO: http://chronos.paasta-mesosstage.yelp/ Mesos: http://mesos.paasta-mesosstage.yelpMesos Status: OK quorum: masters: 3 configured quorum: 2 frameworks: framework: chronos-2.4.0 count: 1 framework: marathon count: 1 CPUs: 1.00 / 7 in use (14.29%) Memory: 3.03 / 42.85GB in use (7.07%) Disk: 10.00 / 153.81GB in use (6.50%) tasks: running: 9 staging: 1 starting: 0 slaves: active: 7 inactive: 0Marathon Status: OK marathon apps: 5 marathon tasks: 9 marathon deployments: 0Chronos Status: OK Enabled chronos jobs: 1 46
$ paasta metastatus
module "nova-devc-useast1a-demo" { source = ".../terraform-modules/paasta_spot_cluster" cluster = "nova-devc" ecosystem = "${var.ecosystem}" min_capacity = 2 max_capacity = 20 initial_target_capacity = 5 ami_type = "paasta" spot_price = 0.1337 instance_profile = "paasta" pool = "demo"}
47
Terraform'ed PaaSTA Pool
● Scaling up is safe and easy● Scaling down can be risky
Scaling Safely
48
● Utilizes Mesos Maintenance Primitives● Attempts to dynamically reserve all available
resources on a host● Scales up the service by the number of instances
running on the host that is in maintenance● Terminates the host once it is fully drained or it
reaches its timeout
PaaSTA Maintenance
49
PaaSTA Components
50
DockerRegistry
Developer
git push
git pull
git push
docker push
50
Marathon
Sensu
52
● More advanced decision policies● Infrastructure-Agnostic● Better integration with PaaSTA/Mesos
Why not AWS (or something else)?
53
@YelpEngineering
fb.com/YelpEngineers
engineeringblog.yelp.com
github.com/yelp54