convox-examples/v2-volumes-example

This repository contains a Python application demonstrating shared volume use between services for deployment on Convox. The application comprises two writing services, each persistently writing to its designated file within a shared volume, showcasing data persistence and sharing capabilities.

Key components:

• Dockerfile
• convox.yml
• writer1.py
• writer2.py

Features

1. Writer 1 Service: Writes timestamped messages to writer1.txt in the shared volume at fixed intervals.
2. Writer 2 Service: Operates similarly to Writer 1, targeting writer2.txt, to illustrate multiple services writing to the same volume.

Shared Volume

The services utilize a Docker volume mounted at /my/shared/data, facilitating data sharing and persistence across container restarts and deployments. This model is useful for applications requiring data availability across multiple service instances or container lifecycles.

Setup and Deployment

For deployment on Convox, ensure the Convox CLI is installed and configured to interact with your Convox Rack. Deploy the application by executing:

convox deploy

This command builds and deploys the application according to the specifications in convox.yml, creating the necessary services and volume configuration.

Observing Output

After deploying your services, you can inspect the operations and outputs of the writer services as follows:

1. List Services: Check the active services for a given application using the convox services -a appName command. You should see your writer services listed:

SERVICE  DOMAIN  PORTS
writer1
writer2

2. Check Running Processes: To view the currently running processes and their IDs, use convox ps -a appName. This will display all active processes for a given application:

ID            SERVICE  STATUS   RELEASE      STARTED         COMMAND
[PROCESS_ID]  writer1  running  [RELEASE]    27 seconds ago  sh -c 'python writer1.py'
[PROCESS_ID]  writer2  running  [RELEASE]    27 seconds ago  sh -c 'python writer2.py'

3. Access Container Shell: To exec into a running container, use convox exec followed by the process ID and the shell command. For example:

convox exec [PROCESS_ID] sh

4. Navigate and Inspect: Within the container's shell, navigate to the shared volume directory and inspect the files written by the services:

# Navigate to shared data directory
cd /my/shared/data
# List files to confirm presence
ls
writer1.txt  writer2.txt
# Display contents of writer1's file
cat writer1.txt
Writer 1 wrote at [timestamp]
# Display contents of writer2's file
cat writer2.txt
Writer 2 wrote at [timestamp]

This process allows you to directly observe the output files writer1.txt and writer2.txt being updated in real-time by the writer services, demonstrating the shared volume functionality.