Thu Feb  1 09:37:47 EST 2018

Slept from eleven to seven without waking.

High of thirty-eight and partly cloudy, but temperatures fall throughout the day.

Work:
- Docker notes
  Done.
  https://paulgorman.org/technical/docker.txt
- Work on MECS
  Done.
- 3:30 PM call with Bullseye and AT&T regarding fiber
  Done.

https://www.tucny.com/telephony/asterisk-rpms
https://fedoraproject.org/wiki/How_to_create_an_RPM_package

Adding storage of recent log entries in MECS, I played with Go's circular list type:

	// cirlist plays with Go's circular list container.
	package main

	import (
		"container/ring"
		"fmt"
	)

	func main() {
		r := ring.New(3)
		for i := 0; i < 10; i++ {
			r = r.Next()
			r.Value = i
			fmt.Println(r.Value)
		}
		fmt.Println("---")
		for i := 0; i < r.Len(); i++ {
			r = r.Next()
			fmt.Println(r.Value)
		}
	}

Twenty-minute walk at lunch.
Sunny and not too cold. Windy.

The complexity of Docker put me off it for a long time, but it might be OK.
It's certainly more robust than systemd-nspawn.
Much more of a real competitor to LXC (though, I admit, the battle seems lost for LXC).

Home:
- Play with ring containers in Go
  Done.

Raspberry Pi variants:
http://www.friendlyarm.com/index.php?route=product/category&path=69

> Boustrophedon is a Greek word meaning “in the manner of an ox,” and scripts written in it move like an ox plowing a field, reversing direction with each line.

https://hub.docker.com/_/busybox/
The fact that Busybox includes runit could be quite useful in a Docker container.

[EDIT: the following is significantly improved in tomorrow's entry.]

	// ringlog uses Go's ring container to keep the latest log entries.
	package main

	// Multiple runs will show that the ringLogger goroutine does not guarantee
	// the exact order of entries. In a non-trivial use, make the ring size
	// large enough to catch all the interesting recent entries.

	import (
		"container/ring"
		"fmt"
		"log"
	)

	var errCount int = -1
	var errCh chan error = make(chan error, 3)
	var errRing = ring.New(5)

	func getTestError() error {
		errCount++
		return fmt.Errorf("test error %v", errCount)
	}

	func ringLogger() {
		for e := range errCh {
			log.Println(e)
			errRing.Value = e
			errRing = errRing.Next()
		}
		close(errCh)
	}

	func main() {
		go ringLogger()
		for i := 0; i < 10; i++ {
			err := getTestError()
			if err != nil {
				errCh <- err
			}
			// Uncomment (and import "time") to see how output regularizes:
			// time.Sleep(time.Millisecond * 100)
		}
		for i := 0; i < errRing.Len(); i++ {
			fmt.Println("Reprint of", errRing.Value)
			errRing = errRing.Next()
		}
	}

Lunch: coffee, falafel bowl
Dinner: pizza