Come up with a name and watch flag

This commit is contained in:
IamTheFij 2018-08-03 17:45:53 -07:00
parent c840d7b0b2
commit da50191759
2 changed files with 19 additions and 13 deletions

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@ -1,28 +1,28 @@
# docker-batch-scheduler # Dockron
WIP for a docker batch scheduler A Dead Simple Docker Cron Scheduler
## Usage ## Usage
$APPNAME requires access to the Docker, so it may need to be run as root, or, if in a Docker container, need the socket mapped as a volume. Dockron requires access to the Docker, so it may need to be run as root, or, if in a Docker container, need the socket mapped as a volume.
### Running $APPNAME ### Running Dockron
As simple as: As simple as:
./$APPNAME dockron
It will then run in the foreground, periodically checking Docker for containers with labels containing a cron schedule. It will then run in the foreground, periodically checking Docker for containers with labels containing a cron schedule.
$APPNAME will periodically poll Docker for new containers or schedule changes. By default, Dockron will periodically poll Docker for new containers or schedule changes every minute. You can specify an interval by using the `-watch` flag.
### Scheduling a container ### Scheduling a container
First, be sure your container is something that is not long running and will actually exit when complete. This is for batch runs and not keeping a service running. Docker should be able to do that on it's own with a restart policy. First, be sure your container is something that is not long running and will actually exit when complete. This is for batch runs and not keeping a service running. Docker should be able to do that on it's own with a restart policy.
Create your container and add a label in the form `$APPNAME.cron.schedule="* * * * *"`, where the value is a valid cron expression (See the section [Cron Expression Formatting](#cron-expression-formatting)). Create your container and add a label in the form `dockron.schedule="* * * * *"`, where the value is a valid cron expression (See the section [Cron Expression Formatting](#cron-expression-formatting)).
$APPNAME will now start that container peridically on the schedule. Dockron will now start that container peridically on the schedule.
### Cron Expression Formatting ### Cron Expression Formatting
@ -30,7 +30,7 @@ For more information on the cron expression parsing, see the docs for [robfig/cr
## Caveats ## Caveats
$APPNAME is quite simple right now. It does not yet: Dockron is quite simple right now. It does not yet:
* Issue any retries * Issue any retries
* Cancel hanging jobs * Cancel hanging jobs
@ -40,4 +40,4 @@ I intend to keep it simple as well. It will likely never:
* Provide any kind of alerting (check out [Minitor](https://git.iamthefij.com/IamTheFij/minitor)) * Provide any kind of alerting (check out [Minitor](https://git.iamthefij.com/IamTheFij/minitor))
* Handle job dependencies * Handle job dependencies
Either use a separate tool in conjunction with $APPNAME, or use a more robust scheduler like Tron, or Chronos. Either use a separate tool in conjunction with Dockron, or use a more robust scheduler like Tron, or Chronos.

12
main.go
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@ -1,6 +1,7 @@
package main package main
import ( import (
"flag"
"fmt" "fmt"
"github.com/docker/docker/api/types" "github.com/docker/docker/api/types"
"github.com/docker/docker/client" "github.com/docker/docker/client"
@ -11,10 +12,10 @@ import (
) )
// WatchInterval is the duration we should sleep until polling Docker // WatchInterval is the duration we should sleep until polling Docker
var WatchInterval = (5 * time.Second) var DefaultWatchInterval = (1 * time.Minute)
// SchedLabel is the string label to search for cron expressions // SchedLabel is the string label to search for cron expressions
var SchedLabel = "cron.schedule" var SchedLabel = "dockron.schedule"
// ContainerStartJob represents a scheduled container task // ContainerStartJob represents a scheduled container task
// It contains a reference to a client, the schedule to run on, and the // It contains a reference to a client, the schedule to run on, and the
@ -78,6 +79,11 @@ func main() {
panic(err) panic(err)
} }
// Read interval for polling Docker
var watchInterval time.Duration
flag.DurationVar(&watchInterval, "watch", DefaultWatchInterval, "Interval used to poll Docker for changes")
flag.Parse()
// Create a Cron // Create a Cron
c := cron.New() c := cron.New()
@ -99,6 +105,6 @@ func main() {
c.Start() c.Start()
// Sleep until the next query time // Sleep until the next query time
time.Sleep(WatchInterval) time.Sleep(watchInterval)
} }
} }