open-nomad/command/init.go

package command

import (
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

const (
	// DefaultInitName is the default name we use when
	// initializing the example file
	DefaultInitName = "example.nomad"
)

// InitCommand generates a new job template that you can customize to your
// liking, like vagrant init
type InitCommand struct {
	Meta
}

func (c *InitCommand) Help() string {
	helpText := `
Usage: nomad init

  Creates an example job file that can be used as a starting
  point to customize further.
`
	return strings.TrimSpace(helpText)
}

func (c *InitCommand) Synopsis() string {
	return "Create an example job file"
}

func (c *InitCommand) Run(args []string) int {
	// Check for misuse
	if len(args) != 0 {
		c.Ui.Error(c.Help())
		return 1
	}

	// Check if the file already exists
	_, err := os.Stat(DefaultInitName)
	if err != nil && !os.IsNotExist(err) {
		c.Ui.Error(fmt.Sprintf("Failed to stat '%s': %v", DefaultInitName, err))
		return 1
	}
	if !os.IsNotExist(err) {
		c.Ui.Error(fmt.Sprintf("Job '%s' already exists", DefaultInitName))
		return 1
	}

	// Write out the example
	err = ioutil.WriteFile(DefaultInitName, []byte(defaultJob), 0660)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Failed to write '%s': %v", DefaultInitName, err))
		return 1
	}

	// Success
	c.Ui.Output(fmt.Sprintf("Example job file written to %s", DefaultInitName))
	return 0
}

var defaultJob = strings.TrimSpace(`
# There can only be a single job definition per file. This job is named
# "example" so it will create a job with the ID and Name "example".
job "example" {
  # Run the job in the global region, which is the default.
  # region = "global"

  # Specify the datacenters within the region this job can run in.
  datacenters = ["dc1"]

  # Service type jobs optimize for long-lived services. This is
  # the default but we can change to batch for short-lived tasks.
  # type = "service"

  # Priority controls our access to resources and scheduling priority.
  # This can be 1 to 100, inclusively, and defaults to 50.
  # priority = 50

  # Restrict our job to only linux. We can specify multiple constraints
  # as needed.
  # constraint {
  #   attribute = "${attr.kernel.name}"
  #   value     = "linux"
  # }

  # Configure the job to do rolling updates
  update {
    # Stagger updates every 10 seconds
    stagger = "10s"

    # Update a single task at a time
    max_parallel = 1
  }

  # Create a 'cache' group. Each task in the group will be scheduled
  # onto the same machine.
  group "cache" {
    # Control the number of instances of this group. Defaults to 1.
    # count = 1

    # Configure the restart policy for the task group. If not provided, a
    # default is used based on the job type.
    restart {
      # The number of attempts to run the job within the specified interval.
      attempts = 10
      interval = "5m"

      # A delay between a task failing and a restart occurring.
      delay = "25s"

      # Mode controls what happens when a task has restarted "attempts"
      # times within the interval. "delay" mode delays the next restart
      # till the next interval. "fail" mode does not restart the task if
      # "attempts" has been hit within the interval.
      mode = "delay"
    }

    ephemeral_disk {
      # When sticky is true and the task group is updated, the scheduler
      # will prefer to place the updated allocation on the same node and
      # will migrate the data. This is useful for tasks that store data
      # that should persist across allocation updates.
      # sticky = true

      # Size of the shared ephemeral disk between tasks in the task group.
      size = 300
    }

    # Define a task to run
    task "redis" {
      # Use Docker to run the task.
      driver = "docker"

      # Configure Docker driver with the image
      config {
        image = "redis:3.2"
        port_map {
          db = 6379
        }
      }

      service {
        # ${TASKGROUP} is filled in automatically by Nomad
        name = "${TASKGROUP}-redis"
        tags = ["global", "cache"]
        port = "db"
        check {
          name     = "alive"
          type     = "tcp"
          interval = "10s"
          timeout  = "2s"
        }
      }

      # We must specify the resources required for this task to ensure
      # it runs on a machine with enough capacity.
      resources {
        cpu    = 500 # 500 MHz
        memory = 256 # 256MB
        network {
          mbits = 10
          port "db" {}
        }
      }

      # The artifact stanza can be specified one or more times to download
      # artifacts prior to the task being started. This is convenient for
      # shipping configs or data needed by the task.
      # artifact {
      #   source = "http://foo.com/artifact.tar.gz"
      #   options {
      #     checksum = "md5:c4aa853ad2215426eb7d70a21922e794"
      #   }
      # }

      # The "template" stanza instructs Nomad to manage a template, such as
      # a configuration file or script. This template can optionally pull data
      # from Consul or Vault to populate runtime configuration data.
      #
      # For more information and examples on the "template" stanza, please see
      # the online documentation at:
      #
      #     https://www.nomadproject.io/docs/job-specification/template.html
      #
      # template {
      #   data          = "---\nkey: {{ key \"service/my-key\" }}"
      #   destination   = "local/file.yml"
      #   change_mode   = "signal"
      #   change_signal = "SIGHUP"
      # }

      # Specify configuration related to log rotation
      # logs {
      #   max_files     = 10
      #   max_file_size = 15
      # }

      # Controls the timeout between signalling a task it will be killed
      # and killing the task. If not set a default is used.
      # kill_timeout = "20s"
    }
  }
}
`)