From 050465b0aad2902d6236967b57eeec798bdfcd4b Mon Sep 17 00:00:00 2001 From: Ian Fijolek Date: Tue, 7 Apr 2020 09:58:12 -0700 Subject: [PATCH] Update jobs only when a new container id is found Rather than trashing the whole schedule, instead compare what is currently scheduled with the newly found containers and then add or remove jobs as needed. Fixes #2 --- Makefile | 3 ++- main.go | 76 +++++++++++++++++++++++++++++++++++++++++----------- main_test.go | 12 +-------- 3 files changed, 63 insertions(+), 28 deletions(-) diff --git a/Makefile b/Makefile index 281d0d9..ba4341d 100644 --- a/Makefile +++ b/Makefile @@ -1,3 +1,4 @@ +.PHONY: test all DOCKER_TAG ?= dockron-dev-${USER} GIT_TAG_NAME := $(shell git tag -l --contains HEAD) GIT_SHA := $(shell git rev-parse HEAD) @@ -13,7 +14,7 @@ vendor: # Runs the application, useful while developing .PHONY: run run: - go run . + go run . -watch 10s -debug .PHONY: test test: diff --git a/main.go b/main.go index 7d6b8e9..eae98bd 100644 --- a/main.go +++ b/main.go @@ -23,6 +23,9 @@ var ( // version of dockron being run version = "dev" + + // Debug can be used to show or supress certain log messages + Debug = true ) // ContainerClient provides an interface for interracting with Docker @@ -46,17 +49,33 @@ type ContainerStartJob struct { // container func (job ContainerStartJob) Run() { log.Println("Starting:", job.Name) - err := job.Client.ContainerStart(job.Context, job.ContainerID, dockerTypes.ContainerStartOptions{}) + err := job.Client.ContainerStart( + job.Context, + job.ContainerID, + dockerTypes.ContainerStartOptions{}, + ) if err != nil { panic(err) } } +// UniqueName returns a unique identifier for a container start job +func (job ContainerStartJob) UniqueName() string { + // ContainerID should be unique as a change in label will result in + // a new container as they are immutable + return job.ContainerID +} + // QueryScheduledJobs queries Docker for all containers with a schedule and // returns a list of ContainerStartJob records to be scheduled func QueryScheduledJobs(client ContainerClient) (jobs []ContainerStartJob) { - log.Println("Scanning containers for new schedules...") - containers, err := client.ContainerList(context.Background(), dockerTypes.ContainerListOptions{All: true}) + if Debug { + log.Println("Scanning containers for new schedules...") + } + containers, err := client.ContainerList( + context.Background(), + dockerTypes.ContainerListOptions{All: true}, + ) if err != nil { panic(err) } @@ -80,16 +99,48 @@ func QueryScheduledJobs(client ContainerClient) (jobs []ContainerStartJob) { // ScheduleJobs accepts a Cron instance and a list of jobs to schedule. // It then schedules the provided jobs func ScheduleJobs(c *cron.Cron, jobs []ContainerStartJob) { + // Fetch existing jobs from the cron + existingJobs := map[string]cron.EntryID{} + for _, entry := range c.Entries() { + existingJobs[entry.Job.(ContainerStartJob).UniqueName()] = entry.ID + } + for _, job := range jobs { - // TODO: Do something with the entryId returned here + if _, ok := existingJobs[job.UniqueName()]; ok { + // Job already exists, remove it from existing jobs so we don't + // unschedule it later + if Debug { + log.Printf("Job %s is already scheduled. Skipping", job.Name) + } + delete(existingJobs, job.UniqueName()) + continue + } + + // Job doesn't exist yet, schedule it _, err := c.AddJob(job.Schedule, job) if err == nil { - log.Printf("Scheduled %s (%s) with schedule '%s'\n", job.Name, job.ContainerID[:10], job.Schedule) + log.Printf( + "Scheduled %s (%s) with schedule '%s'\n", + job.Name, + job.ContainerID[:10], + job.Schedule, + ) } else { // TODO: Track something for a healthcheck here - log.Printf("Error scheduling %s (%s) with schedule '%s'. %v\n", job.Name, job.ContainerID[:10], job.Schedule, err) + log.Printf( + "Error scheduling %s (%s) with schedule '%s'. %v\n", + job.Name, + job.ContainerID[:10], + job.Schedule, + err, + ) } } + + // Remove remaining scheduled jobs that weren't in the new list + for _, entryID := range existingJobs { + c.Remove(entryID) + } } func main() { @@ -103,6 +154,7 @@ func main() { var watchInterval time.Duration flag.DurationVar(&watchInterval, "watch", defaultWatchInterval, "Interval used to poll Docker for changes") var showVersion = flag.Bool("version", false, "Display the version of dockron and exit") + flag.BoolVar(&Debug, "debug", false, "Show debug logs") flag.Parse() // Print version if asked @@ -113,22 +165,14 @@ func main() { // Create a Cron c := cron.New() + c.Start() // Start the loop for { - // HACK: This is risky as it could fall on the same interval as a task and that task would get skipped - // It would be best to manage a ContainerID to Job mapping and then remove entries that are missing - // in the new list and add new entries. However, cron does not support this yet. - - // Stop and create a new cron - c.Stop() - c = cron.New() - + // Schedule jobs again jobs := QueryScheduledJobs(client) ScheduleJobs(c, jobs) - c.Start() - // Sleep until the next query time time.Sleep(watchInterval) } diff --git a/main_test.go b/main_test.go index fccafe8..0b36662 100644 --- a/main_test.go +++ b/main_test.go @@ -171,10 +171,7 @@ func TestScheduleJobs(t *testing.T) { } }) - // Subsequently scheduled jobs will append since we currently just stop and create a new cron - // Eventually this test case should change when proper removal is supported - - t.Run("Schedule a second job", func(t *testing.T) { + t.Run("Schedule a second job removing the first", func(t *testing.T) { log.Printf("Running %s", t.Name()) jobs := []ContainerStartJob{ ContainerStartJob{ @@ -184,13 +181,6 @@ func TestScheduleJobs(t *testing.T) { }, } ScheduleJobs(c, jobs) - jobs = append([]ContainerStartJob{ - ContainerStartJob{ - ContainerID: "0123456789/has_schedule_1", - Name: "has_schedule_1", - Schedule: "* * * * *", - }, - }, jobs...) scheduledEntries := c.Entries()