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

---
layout: docs
page_title: meta block in the job specification
description: |-
  Define arbitrary metadata in the `meta` block of the Nomad job specification. Configure runtime environment variables for tasks to consume. Review examples that use Nomad interpolation and templates.
---

# `meta` block in the job specification

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

The `meta` block allows for user-defined arbitrary key-value pairs. It is
possible to use the `meta` block at the [job][], [group][], or [task][] level.

```hcl
job "docs" {
  meta {
    my-key = "my-value"
  }

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

    task "server" {
      meta {
        my-key = "my-value"
      }
    }
  }
}
```

Metadata is merged up the job specification, so metadata defined at the job
level applies to all groups and tasks within that job. Metadata defined at the
group layer applies to all tasks within that group.

Meta values are made available inside tasks as [runtime environment variables][env_meta].

## Parameters

The "parameters" for the `meta` block can be any key-value. The keys and values
are both of type `string`, but they can be specified as other types. They will
automatically be converted to strings. Any character in a key other than
`[A-Za-z0-9_.]` will be converted to `_`.

## Examples

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

### Coercion

This example shows the different ways to specify key-value pairs. Internally,
these values will be stored as their string representation. No type information
is preserved.

```hcl
meta {
  key = "true"
  key = true

  key = 1.4
  key = "1.4"
}
```

### Interpolation

This example shows using [Nomad interpolation][interpolation] to populate
environment variables.

```hcl
meta {
  class = "${node.class}"
}
```

### Meta keys with dots

Meta keys that aren't valid HCLv2 identifiers, like ones containing `.`, require an alternative map assignment syntax.

```hcl
meta = {
  "project.team" = "sre"
}
```

## Template usage example

To make use of a `meta` value in a template, refer to its environment variable
form.

```hcl
template {
  destination = "local/out.txt"
  data = <<EOH
  {{ env "NOMAD_META_mykey" }}
EOH
}
```

[job]: /nomad/docs/job-specification/job 'Nomad job Job Specification'
[group]: /nomad/docs/job-specification/group 'Nomad group Job Specification'
[task]: /nomad/docs/job-specification/task 'Nomad task Job Specification'
[interpolation]: /nomad/docs/reference/runtime-variable-interpolation 'Nomad interpolation'
[env_meta]: /nomad/docs/reference/runtime-environment-settings#meta-block-for-arbitrary-configuration