nomad/website/content/docs/job-specification/group.mdx

---
layout: docs
page_title: group block in the job specification
description: |-
  Define a series of co-located tasks in the `group` block of the Nomad job specification. Specify constraints, affinities, spreads, number of instances, Consul settings, ephemeral disks, disconnect strategy, metadata, migration strategy, network requirements, rescheduling strategy, restart policy, service discovery, shutdown delay, task update strategy, Vault policies, and required volumes. Review count, constraints, metadata, network, and service discovery examples.
---

# `group` block in the job specification

<Placement groups={['job', 'group']} />

The `group` block defines a series of tasks that should be co-located on the
same Nomad client. Any [task][] within a group will be placed on the same
client.

```hcl
job "docs" {
  group "example" {
    # ...
  }
}
```

## Parameters

- `constraint` <code>([Constraint][]: nil)</code> -
  This can be provided multiple times to define additional constraints.

- `affinity` <code>([Affinity][]: nil)</code> - This can be provided
  multiple times to define preferred placement criteria.

- `spread` <code>([Spread][spread]: nil)</code> - This can be provided
  multiple times to define criteria for spreading allocations across a
  node attribute or metadata. See the
  [Nomad spread reference](/nomad/docs/job-specification/spread) for more details.

- `count` `(int)` - Specifies the number of instances that should be running
  under for this group. This value must be non-negative. This defaults to the
  `min` value specified in the [`scaling`](/nomad/docs/job-specification/scaling)
  block, if present; otherwise, this defaults to `1`.

- `consul` <code>([Consul][consul]: nil)</code> - Specifies Consul configuration
  options specific to the group. These options will be applied to all tasks and
  services in the group unless a task has its own `consul` block.

- `ephemeral_disk` <code>([EphemeralDisk][]: nil)</code> - Specifies the
  ephemeral disk requirements of the group. Ephemeral disks can be marked as
  sticky and support live data migrations.

- `disconnect` <code>([disconnect][]: nil)</code> - Specifies the disconnect
  strategy for the server and client for all tasks in this group in case of a
  network partition. The tasks can be left unconnected, stopped or replaced
  when the client disconnects. The policy for reconciliation in case the client
  regains connectivity is also specified here.

- `meta` <code>([Meta][]: nil)</code> - Specifies a key-value map that annotates
  with user-defined metadata.

- `migrate` <code>([Migrate][]: nil)</code> - Specifies the group strategy for
  migrating off of draining nodes. Only service jobs with a count greater than
  1 support migrate blocks.

- `network` <code>([Network][]: &lt;optional&gt;)</code> - Specifies the network
  requirements and configuration, including static and dynamic port allocations,
  for the group.

- `reschedule` <code>([Reschedule][]: nil)</code> - Allows to specify a
  rescheduling strategy. Nomad will then attempt to schedule the task on another
  node if any of the group allocation statuses become "failed".

- `restart` <code>([Restart][]: nil)</code> - Specifies the restart policy for
  all tasks in this group. If omitted, a default policy exists for each job
  type, which can be found in the [restart block documentation][restart].

- `service` <code>([Service][]: nil)</code> - Specifies integrations with Nomad
  or [Consul](/nomad/docs/configuration/consul) for service discovery. Nomad
  automatically registers each service when an allocation is started and
  de-registers them when the allocation is destroyed.

- `shutdown_delay` `(string: "0s")` - Specifies the duration to wait when
  stopping a group's tasks. The delay occurs between Consul or Nomad service
  deregistration and sending each task a shutdown signal. Ideally, services
  would fail health checks once they receive a shutdown signal. Alternatively,
  `shutdown_delay` may be set to give in-flight requests time to complete
  before shutting down. A group level `shutdown_delay` will run regardless
  if there are any defined group [services](/nomad/docs/job-specification/group#service)
  and only applies to these services. In addition, tasks may have their own
  [`shutdown_delay`](/nomad/docs/job-specification/task#shutdown_delay) which waits
  between de-registering task services and stopping the task.

- `task` <code>([Task][]: &lt;required&gt;)</code> - Specifies one or more tasks to run
  within this group. This can be specified multiple times, to add a task as part
  of the group.

- `update` <code>([Update][update]: nil)</code> - Specifies the task's update
  strategy. When omitted, a default update strategy is applied.

- `vault` <code>([Vault][]: nil)</code> - Specifies the set of Vault policies
  required by all tasks in this group. Overrides a `vault` block set at the
  `job` level.

- `volume` <code>([Volume][]: nil)</code> - Specifies the volumes that are
  required by tasks within the group.

## Examples

The following examples only show the `group` blocks. Remember that the
`group` block is only valid in the placements listed above.

### Specifying Count

This example specifies that 5 instances of the tasks within this group should be
running:

```hcl
group "example" {
  count = 5
}
```

### Tasks with constraint

This example shows two abbreviated tasks with a constraint on the group. This
will restrict the tasks to 64-bit operating systems.

```hcl
group "example" {
  constraint {
    attribute = "${attr.cpu.arch}"
    value     = "amd64"
  }

  task "cache" {
    # ...
  }

  task "server" {
    # ...
  }
}
```

### Metadata

This example show arbitrary user-defined metadata on the group:

```hcl
group "example" {
  meta {
    my-key = "my-value"
  }
}
```

### Network

This example shows network constraints as specified in the [network][] block
which uses the `bridge` networking mode, dynamically allocates two ports, and
statically allocates one port:

```hcl
group "example" {
  network {
    mode = "bridge"
    port "http" {}
    port "https" {}
    port "lb" {
      static = "8889"
    }
  }
}
```

### Service discovery

This example creates a service in Consul. To read more about service discovery
in Nomad, please see the [Nomad service discovery documentation][service_discovery].

```hcl
group "example" {
  network {
    port "api" {}
  }

  service {
    name = "example"
    port = "api"
    tags = ["default"]

    check {
      type     = "tcp"
      interval = "10s"
      timeout  = "2s"
    }
  }

  task "api" { ... }
}
```

[task]: /nomad/docs/job-specification/task 'Nomad task Job Specification'
[job]: /nomad/docs/job-specification/job 'Nomad job Job Specification'
[constraint]: /nomad/docs/job-specification/constraint 'Nomad constraint Job Specification'
[consul]: /nomad/docs/job-specification/consul
[consul_namespace]: /nomad/docs/commands/job/run#consul-namespace
[spread]: /nomad/docs/job-specification/spread 'Nomad spread Job Specification'
[affinity]: /nomad/docs/job-specification/affinity 'Nomad affinity Job Specification'
[ephemeraldisk]: /nomad/docs/job-specification/ephemeral_disk 'Nomad ephemeral_disk Job Specification'
[`heartbeat_grace`]: /nomad/docs/configuration/server#heartbeat_grace
[`disable_rescheduling`]: /nomad/docs/job-specification/reschedule#disabling-rescheduling
[meta]: /nomad/docs/job-specification/meta 'Nomad meta Job Specification'
[migrate]: /nomad/docs/job-specification/migrate 'Nomad migrate Job Specification'
[network]: /nomad/docs/job-specification/network 'Nomad network Job Specification'
[reschedule]: /nomad/docs/job-specification/reschedule 'Nomad reschedule Job Specification'
[disconnect]: /nomad/docs/job-specification/disconnect 'Nomad disconnect Job Specification'
[restart]: /nomad/docs/job-specification/restart 'Nomad restart Job Specification'
[service]: /nomad/docs/job-specification/service 'Nomad service Job Specification'
[service_discovery]: /nomad/docs/integrations/consul-integration#service-discovery 'Nomad Service Discovery'
[update]: /nomad/docs/job-specification/update 'Nomad update Job Specification'
[vault]: /nomad/docs/job-specification/vault 'Nomad vault Job Specification'
[volume]: /nomad/docs/job-specification/volume 'Nomad volume Job Specification'
[`consul.name`]: /nomad/docs/configuration/consul#name
[disconect_migration]: /nomad/docs/job-specification/group#migration_to_disconnect_block