The document discusses using Docker containers to enable a solar panel monitoring application to support multiple service providers. It describes setting up Docker containers for the TCP data ingestion server and Flask admin application for each provider, linking them to a Cassandra database container. Each provider's instances use a unique Cassandra keyspace to isolate their data. Automating this process using Docker Python APIs allows easily scaling to support additional providers. Lessons learned include Docker providing fast isolation without code changes, and needing improved Docker orchestration and Dockerfile support for multiple commands.

1. DOCKER @ FLUX7 LABS

2. DOCKER AUSTIN
FOR MORE DISCUSSIONS ON DOCKER!

3. Who am I?
● Aater Suleman
○ Part-time UT Professor
○ Geek, Architect, Developer, Ops, DevOps …
● Co-founder & CEO Flux7 Labs
○ DevOps Solutions
■ Deployments
■ Cost/performance optimized large scale
website (Ruby on rails, node.js, Django) and
Hadoop deployments

4. Four projects:
VyScale Dev Flow
Docker's impact on performance (whitepaper WIP)
Multi-tenancy
Live process migration using CRIU (criu.org)

5. Application: Single Service Provider
Internet of Things -- Solar Panel Monitoring
Receive
Sensor Data
XML Data
over TCP
Report
Generation
based on data
Big Data
Analytics
Report sent to
End User

6. Gateway3
sensors
Gateway1
Gateway2
Location1
Location3
Location2
Provider Span
A provider has Mifi routers installed at
multiple Locations which collect data from
sensors and sends it to a remote TCP
server via the internet.
Browser
Uses the Flask
app at port 80
Internet
Flask App
Port 80
TCP server
Port 6000
Cassandra
port 9160
Single Provider System

7. COMPONENTS
1. Cassandra for data persistence which we later use for generating reports
for each gateway.
2. A Twisted TCP server listening at PORT 6000, for data ingestion from
multiple gateways owned by the provider.
3. A Flask app serving at PORT 80 as the admin panel for setting
customizations and viewing reports.

8. Customer 1
G
Customer 2 …
Customer N
G
G
G
Each customer can have
multiple gateways
commissioned to them.
*G - Gateway
Remote Twister TCP Server
(Non–Blocking I/O)
Web App
Power consumption
status on website and
mails
Mailer
Cassandra NoSQL data store
(High Volume High Velocity Write
which scales Linearly across the
cluster )

9. SINGLE PROVIDER LAUNCH
For launching the single provider version, the following was done:
1. nohup python tcp_server.py & # For firing up the TCP server.
2. nohup python flask_app.py &
# For firing up the admin panel
Both these code bases houses hard-coded Cassandra KEYSPACE
Success!

10. Application: Multiple Service Providers
…

11. Provider 2 sends data to port
6002 and accesses flask app at
port 8082
Provider 1 sends
data to port 6001
and accesses flask
app at port 8081
Internet
TCP server containerruns at port 6000.
Exposes port 6000 and
published it to port 6001
for provider 1
Flask container-runs
flask app at port 80.
Exposes port 80 and
published it to port 8081
for provider 1
TCP server container-runs
at port 6000. Exposes
port 6000 and published it
to port 6002 for provider 2
Flask container-runs flask
app at port 80. Exposes
port 80 and published it to
port 8082 for provider 2
Cassandra

12. KNEE-JERK APPROACH
Sprinkle Tenant ID everywhere in the code and DB
Time consuming
Poor isolation
Security
Expensive
Maintenance
Rigidity

13. MULTIPLE HOST/VMS
An alternate solution is to use Virtual Machine (VM)
Hosts are expensive ($)
VMs are expensive (high overhead)

14. AND THE SOLUTION

15. WHY DOCKER?
Docker containers provide isolation that is
Fast
Inexpensive
How: Isolated environments for running multiple instances of the app

16. PLAN
Create a docker container for the new version of the app
Setup environments/dependencies correctly
Start a Cassandra container.

17. AUTOMATION
An automation was the next foreseeable step, and for that we found Docker-py
extremely useful. We used something like:
# Yes. We love Python!
def start_provider(provider_id, gateway_port, admin_port ):
docker_client = docker.Client(base_url='unix://var/run/docker.sock', version='1.6',
timeout=100)
# start a docker container for consuming gateway data at gateway_port
start_command = 'python software/remote_server.py ' + provider_id
remote_server = docker_client.create_container('flux7/labs', # docker image
command=start_command, # start command contains the keyspace parameter, keyspace is the
provider_id
name='remote_server_' + provider_id, # name the container, name is provider_id
ports=[(6000, 'tcp'),]) # open port for binding, remote_server.py listens at 6000
docker_client.start(remote_server, port_bindings={6000: ('0.0.0.0', gateway_port)},
links={'db': 'cassandra'})
# start a docker container for serving admin panel at admin_port
start_command = 'python software/flask_app.py ' + provider_id
remote_server = docker_client.create_container('flux7/labs', # docker image
command=start_command, # start command contains the keyspace parameter, keyspace is the
provider_id
name='admin_panel_' + provider_id, # name the container, name is provider_id
ports=[(80, 'tcp'),]) # open port for binding, remote_server.py listens at 6000
docker_client.start(remote_server, port_bindings={80: ('0.0.0.0',admin_port)}, links=
{'db': 'cassandra'})

18. OUR SOLUTION- EXPLAINED
For now, a locally running container serving at PORT 9160 using the command
similar to this:
docker run -d -p 9160:9160 -name db flux7/cassandra

19. OUR SOLUTION- EXPLAINED
▪ Create a keyspace ‘provider1’ using pycassaShell.
We fired up our two code bases on two separate containers like this:
docker run -name remote_server_1 -link db:cassandra p 6000:6000 flux7/labs python software/remote_server.
py provider1
docker run -name flask_app_1 -link db:cassandra -p
6000:6000 flux7/labs python software/flask_app.py
provider1

20. DOCKER ISSUES DISCOVERED
Docker does not support multiple instances of Cassandra running on the
same machine.
Hosting multiple database instances on a single machine can quickly
cause resource shortages

21. OUR SOLUTION
❑ Followed the traditional solution to make an application multi-tenant
Use of KEYSPACE as the namespace for each provider in the data store
Code Changes
Cassandra
KEYSPACE /
provider ID
•• To data ingestion server and web server by adding
the keyspace parameter to the DB accesses.
•• Passed to each instance of the app on the
command line.
❑ Each provider in the data store gets a separate namespace without making
any changes to the column family schema.

22. LESSONS WE LEARNED
1.
Docker is an extremely fast and elegant isolation framework: easy to
port, cheap to run, easy to orchestrate
2.
Multi-tenancy != changing the app to support multiple tenants
3.
Docker orchestration frameworks are not at par with Docker today.
What we have written is yet another one but for multi-tenancy.
4.
Dockerfiles still need work -- we used shell scripts in some places
5.
We can run multiple commands/container

23. DOCKER AUSTIN
FOR MORE DISCUSSIONS ON DOCKER!