When working with runit on Ubuntu 12.04, the error "unable to open supervise/ok: file does not exist" typically indicates a service initialization problem. The supervise/ok file is crucial as it's created by runit when a service is properly started and supervised.

First, verify your service directory structure. A properly configured service should have:

/etc/sv/myapp/
├── run
├── log/
│   └── run
└── config (optional)

Your symlink creation seems correct:

sudo ln -s /etc/sv/myapp /service/myapp

Common causes for this error include:

• Incorrect permissions on /service directory (should be 1755)
• Missing execute permission on run scripts
• Incorrect ownership (should be root:root)

Run these commands to verify:

ls -ld /service
ls -l /etc/sv/myapp/run
ls -l /etc/sv/myapp/log/run

For manual debugging, try:

cd /etc/sv/myapp
./run

If the script runs manually but not via runit, check for:

• Environment variable differences
• Path issues in your run script
• Missing dependencies

While restarting svscan might help, a more thorough approach is:

sudo pkill svscan
sudo /usr/bin/svscanboot &

Then watch the logs:

tail -f /var/log/syslog | grep svscan

Here's a complete working example for a simple service:

# /etc/sv/myservice/run
#!/bin/sh
exec 2>&1
exec /usr/local/bin/myservice --config /etc/myservice.conf

Log directory setup:

# /etc/sv/myservice/log/run
#!/bin/sh
exec svlogd -tt /var/log/myservice

Set permissions:

sudo chmod +x /etc/sv/myservice/run
sudo chmod +x /etc/sv/myservice/log/run
sudo chown -R root:root /etc/sv/myservice

If issues persist:

• Verify runit is properly installed: dpkg -l | grep runit
• Check for conflicts with other init systems
• Consider upgrading from Ubuntu 12.04 (EOL)

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The error message you're encountering typically occurs when runit's supervision tree isn't properly initialized. The supervise/ok file is a critical component that runit creates when a service is correctly set up and running.

For runit to work properly, your service directory should have this basic structure:

/etc/sv/myapp/
├── run
├── log/
│   └── run
└── config (optional)

When the supervise/ok file is missing, it usually indicates one of these scenarios:

• The service was never properly started
• Permissions prevent runit from creating the supervise directory
• The symlink wasn't created correctly
• svscan isn't running

1. Verify Service Directory Structure

First, ensure your run script is executable:

chmod +x /etc/sv/myapp/run
chmod +x /etc/sv/myapp/log/run

2. Check Symlink Creation

Instead of creating the symlink manually, use runit's recommended approach:

ln -s /etc/sv/myapp /service/

3. Validate svscan Operation

Ensure svscan is actually running:

ps aux | grep svscan

If it's not running, start it properly:

sudo /usr/bin/svscanboot &

4. Force Service Recreation

Sometimes removing and recreating the service helps:

sudo rm -rf /service/myapp
sudo ln -s /etc/sv/myapp /service/
sudo sv restart myapp

For deeper investigation, check the supervise directory permissions:

ls -la /etc/sv/myapp/supervise

The directory should be owned by root and have these permissions:

drwx------ 2 root root 4096 Apr 10 10:00 supervise

Here's a complete example for a simple service:

# /etc/sv/example/run
#!/bin/sh
exec 2>&1
exec /usr/local/bin/example-service --config /etc/example.conf

And the log runner:

# /etc/sv/example/log/run
#!/bin/sh
exec svlogd -tt /var/log/example

If the issue persists, try using runsvdir directly for testing:

sudo runsvdir /service &

This can help determine if the issue is with svscanboot or the service configuration itself.