mediocre-go-lib/m/m.go

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// Package m is the glue which holds all the other packages in this project
// together. While other packages in this project are intended to be able to be
// used separately and largely independently, this package combines them in ways
// which I specifically like.
package m
import (
"os"
"os/signal"
"github.com/mediocregopher/mediocre-go-lib/mcfg"
"github.com/mediocregopher/mediocre-go-lib/mctx"
"github.com/mediocregopher/mediocre-go-lib/merr"
"github.com/mediocregopher/mediocre-go-lib/mlog"
"github.com/mediocregopher/mediocre-go-lib/mrun"
)
// CfgSource returns an mcfg.Source which takes in configuration info from the
// environment and from the CLI.
func CfgSource() mcfg.Source {
return mcfg.Sources{
mcfg.SourceEnv{},
mcfg.SourceCLI{},
}
}
// TODO Create a function, `NewService() mctx.Context` which preloads the
// context with log-level param. Will one day also add debug server. Problem
// comes because mlog isn't quite designed right and setting log-level from
// config won't propagate changes to child contexts which have already called
// mlog.From.
// Run performs the work of populating configuration parameters, triggering the
// start event, waiting for an interrupt, and then triggering the stop event.
// Run will block until the stop event is done. If any errors are encountered a
// fatal is thrown.
func Run(ctx mctx.Context) {
log := mlog.From(ctx)
if err := mcfg.Populate(ctx, CfgSource()); err != nil {
log.Fatal("error populating configuration", merr.KV(err))
} else if err := mrun.Start(ctx); err != nil {
log.Fatal("error triggering start event", merr.KV(err))
}
{
ch := make(chan os.Signal, 1)
signal.Notify(ch, os.Interrupt)
s := <-ch
log.Info("signal received, stopping", mlog.KV{"signal": s})
}
if err := mrun.Stop(ctx); err != nil {
log.Fatal("error triggering stop event", merr.KV(err))
}
log.Info("exiting process")
}