---
layout: "docs"
page_title: "Internals: Machine-Readable UI"
sidebar_current: "docs-internals-machine-readable-ui"
description: |-
  Terraform provides a machine-readable streaming JSON UI output for plan, apply, and refresh operations.
---

# Machine-Readable UI

-> **Note:** This format is available in Terraform 0.15.3 and later.

By default, many Terraform commands display UI output as unstructured text, intended to be read by a user via a terminal emulator. This text stream is not a stable interface for integrations. Some commands support a `-json` flag, which enables a structured JSON output mode with a defined interface.

For long-running commands such as `plan`, `apply`, and `refresh`, the `-json` flag outputs a stream of JSON UI messages, one per line. These can be processed one message at a time, with integrating software filtering, combining, or modifying the output as desired.

-> **Note:** The first message output has type `version`, and includes a `ui` key, which currently has major version zero to indicate that the format is experimental and subject to change. A future version will assign a non-zero major version and make stronger promises about compatibility. We do not anticipate any significant breaking changes to the format before its first major version, however.

## Sample JSON Output

Below is sample output from running `terraform apply -json`:

```javascript
{"@level":"info","@message":"Terraform 0.15.4","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.275359-04:00","terraform":"0.15.4","type":"version","ui":"0.1.0"}
{"@level":"info","@message":"random_pet.animal: Plan to create","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.705503-04:00","change":{"resource":{"addr":"random_pet.animal","module":"","resource":"random_pet.animal","implied_provider":"random","resource_type":"random_pet","resource_name":"animal","resource_key":null},"action":"create"},"type":"planned_change"}
{"@level":"info","@message":"Plan: 1 to add, 0 to change, 0 to destroy.","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.705638-04:00","changes":{"add":1,"change":0,"remove":0,"operation":"plan"},"type":"change_summary"}
{"@level":"info","@message":"random_pet.animal: Creating...","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.825308-04:00","hook":{"resource":{"addr":"random_pet.animal","module":"","resource":"random_pet.animal","implied_provider":"random","resource_type":"random_pet","resource_name":"animal","resource_key":null},"action":"create"},"type":"apply_start"}
{"@level":"info","@message":"random_pet.animal: Creation complete after 0s [id=smart-lizard]","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.826179-04:00","hook":{"resource":{"addr":"random_pet.animal","module":"","resource":"random_pet.animal","implied_provider":"random","resource_type":"random_pet","resource_name":"animal","resource_key":null},"action":"create","id_key":"id","id_value":"smart-lizard","elapsed_seconds":0},"type":"apply_complete"}
{"@level":"info","@message":"Apply complete! Resources: 1 added, 0 changed, 0 destroyed.","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.869168-04:00","changes":{"add":1,"change":0,"remove":0,"operation":"apply"},"type":"change_summary"}
{"@level":"info","@message":"Outputs: 1","@module":"terraform.ui","@timestamp":"2021-05-25T13:32:41.869280-04:00","outputs":{"pets":{"sensitive":false,"type":"string","value":"smart-lizard"}},"type":"outputs"}
```

Each line consists of a JSON object with several keys common to all messages. These are:

- `@level`: this is normally "info", but can be "error" or "warn" when showing diagnostics
- `@message`: a human-readable summary of the contents of this message
- `@module`: always "terraform.ui" when rendering UI output
- `@timestamp`: an RFC3339 timestamp of when the message was output
- `type`: defines which kind of message this is and determines how to interpret other keys which may be present

Clients presenting the logs as a user interface should handle unexpected message types by presenting at least the `@message` field to the user.

Messages will be emitted as events occur to trigger them. This means that messages related to several resources may be interleaved (if Terraform is running with concurrency above 1). The [`resource` object value](#resource-object) can be used to link multiple messages about a single resource.

## Message Types

The following message types are supported:

### Generic Messages

- `version`: information about the Terraform version and the version of the schema used for the following messages
- `log`: unstructured human-readable log lines
- `diagnostic`: diagnostic warning or error messages; [see the `terraform validate` docs for more details on the format](/docs/cli/commands/validate.html#json)

### Operation Results

- `resource_drift`: describes a detected change to a single resource made outside of Terraform
- `planned_change`: describes a planned change to a single resource
- `change_summary`: summary of all planned or applied changes
- `outputs`: list of all root module outputs

### Resource Progress

- `apply_start`, `apply_progress`, `apply_complete`, `apply_errored`: sequence of messages indicating progress of a single resource through apply
- `provision_start`, `provision_progress`, `provision_complete`, `provision_errored`: sequence of messages indicating progress of a single provisioner step
- `refresh_start`, `refresh_complete`: sequence of messages indicating progress of a single resource through refresh

## Version Message

A machine-readable UI command output will always begin with a `version` message. The following message-specific keys are defined:

- `terraform`: the Terraform version which emitted this message
- `ui`: the machine-readable UI schema version defining the meaning of the following messages

### Example

```json
{
  "@level": "info",
  "@message": "Terraform 0.15.4",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.275359-04:00",
  "terraform": "0.15.4",
  "type": "version",
  "ui": "0.1.0"
}
```

## Resource Drift

If drift is detected during planning, Terraform will emit a `resource_drift` message for each resource which has changed outside of Terraform. This message has an embedded `change` object with the following keys:

- `resource`: object describing the address of the resource to be changed; see [resource object](#resource-object) below for details
- `action`: the action planned to be taken for the resource. Values: `update`, `delete`.

This message does not include details about the exact changes which caused the change to be planned. That information is available in [the JSON plan output](./json-format.html).

### Example

```json
{
  "@level": "info",
  "@message": "random_pet.animal: Drift detected (update)",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.705503-04:00",
  "change": {
    "resource": {
      "addr": "random_pet.animal",
      "module": "",
      "resource": "random_pet.animal",
      "implied_provider": "random",
      "resource_type": "random_pet",
      "resource_name": "animal",
      "resource_key": null
    },
    "action": "update"
  },
  "type": "resource_drift"
}
```

## Planned Change

At the end of a plan or before an apply, Terraform will emit a `planned_change` message for each resource which has changes to apply. This message has an embedded `change` object with the following keys:

- `resource`: object describing the address of the resource to be changed; see [resource object](#resource-object) below for details
- `previous_resource`: object describing the previous address of the resource, if this change includes a configuration-driven move
- `action`: the action planned to be taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`, `move`.
- `reason`: an optional reason for the change, currently only used when the action is `replace`. Values:
    - `tainted`: resource was marked as tainted
    - `requested`: user requested that the resource be replaced, for example via the `-replace` plan flag
    - `cannot_update`: changes to configuration force the resource to be deleted and created rather than updated

This message does not include details about the exact changes which caused the change to be planned. That information is available in [the JSON plan output](./json-format.html).

### Example

```json
{
  "@level": "info",
  "@message": "random_pet.animal: Plan to create",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.705503-04:00",
  "change": {
    "resource": {
      "addr": "random_pet.animal",
      "module": "",
      "resource": "random_pet.animal",
      "implied_provider": "random",
      "resource_type": "random_pet",
      "resource_name": "animal",
      "resource_key": null
    },
    "action": "create"
  },
  "type": "planned_change"
}
```

## Change Summary

Terraform outputs a change summary when a plan or apply operation completes. Both message types include a `changes` object, which has the following keys:

- `add`: count of resources to be created (including as part of replacement)
- `change`: count of resources to be changed in-place
- `remove`: count of resources to be destroyed (including as part of replacement)
- `operation`: one of `plan`, `apply`, or `destroy`

### Example

```json
{
  "@level": "info",
  "@message": "Apply complete! Resources: 1 added, 0 changed, 0 destroyed.",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.869168-04:00",
  "changes": {
    "add": 1,
    "change": 0,
    "remove": 0,
    "operation": "apply"
  },
  "type": "change_summary"
}
```

## Outputs

After a successful plan or apply, a message with type `outputs` contains the values of all root module output values. This message contains an `outputs` object, the keys of which are the output names. The outputs values are objects with the following keys:

- `action`: for planned outputs, the action which will be taken for the output. Values: `noop`, `create`, `update`, `delete`
- `value`: for applied outputs, the value of the output, encoded in JSON
- `type`: for applied outputs, the detected HCL type of the output value
- `sensitive`: boolean value, `true` if the output is sensitive and should be hidden from UI by default

Note that `sensitive` outputs still include the `value` field, and integrating software should respect the sensitivity value as appropriate for the given use case.

### Example

```json
{
  "@level": "info",
  "@message": "Outputs: 1",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.869280-04:00",
  "outputs": {
    "pets": {
      "sensitive": false,
      "type": "string",
      "value": "smart-lizard"
    }
  },
  "type": "outputs"
}
```

## Operation Messages

Performing Terraform operations to a resource will often result in several messages being emitted. The message types include:

- `apply_start`: when starting to apply changes for a resource
- `apply_progress`: periodically, showing elapsed time output
- `apply_complete`: on successful operation completion
- `apply_errored`: when an error is encountered during the operation
- `provision_start`: when starting a provisioner step
- `provision_progress`: on provisioner output
- `provision_complete`: on successful provisioning
- `provision_errored`: when an error is enountered during provisioning
- `refresh_start`: when reading a resource during refresh
- `refresh_complete`: on successful refresh

Each of these messages has a `hook` object, which has different fields for each type. All hooks have a [`resource` object](#resource-object) which identifies which resource is the subject of the operation.

## Apply Start

The `apply_start` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `action`: the action to be taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`
- `id_key` and `id_value`: a key/value pair used to identify this instance of the resource, omitted when unknown

### Example

```json
{
  "@level": "info",
  "@message": "random_pet.animal: Creating...",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.825308-04:00",
  "hook": {
    "resource": {
      "addr": "random_pet.animal",
      "module": "",
      "resource": "random_pet.animal",
      "implied_provider": "random",
      "resource_type": "random_pet",
      "resource_name": "animal",
      "resource_key": null
    },
    "action": "create"
  },
  "type": "apply_start"
}
```

## Apply Progress

The `apply_progress` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `action`: the action being taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`
- `elapsed_seconds`: time elapsed since the apply operation started, expressed as an integer number of seconds

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[4]: Still creating... [30s elapsed]",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-17T09:34:26.222465-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[4]",
      "module": "",
      "resource": "null_resource.none[4]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 4
    },
    "action": "create",
    "elapsed_seconds": 30
  },
  "type": "apply_progress"
}
```

## Apply Complete

The `apply_complete` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `action`: the action taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`
- `id_key` and `id_value`: a key/value pair used to identify this instance of the resource, omitted when unknown
- `elapsed_seconds`: time elapsed since the apply operation started, expressed as an integer number of seconds

### Example

```json
{
  "@level": "info",
  "@message": "random_pet.animal: Creation complete after 0s [id=smart-lizard]",
  "@module": "terraform.ui",
  "@timestamp": "2021-05-25T13:32:41.826179-04:00",
  "hook": {
    "resource": {
      "addr": "random_pet.animal",
      "module": "",
      "resource": "random_pet.animal",
      "implied_provider": "random",
      "resource_type": "random_pet",
      "resource_name": "animal",
      "resource_key": null
    },
    "action": "create",
    "id_key": "id",
    "id_value": "smart-lizard",
    "elapsed_seconds": 0
  },
  "type": "apply_complete"
}
```

## Apply Errored

The `apply_complete` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `action`: the action taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`
- `elapsed_seconds`: time elapsed since the apply operation started, expressed as an integer number of seconds

The exact detail of the error will be rendered as a separate `diagnostic` message.

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: Creation errored after 10s",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T16:38:54.013910-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "action": "create",
    "elapsed_seconds": 10
  },
  "type": "apply_errored"
}
```

## Provision Start

The `provision_start` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `provisioner`: the type of provisioner

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: Provisioning with 'local-exec'...",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T16:38:43.997431-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "provisioner": "local-exec"
  },
  "type": "provision_start"
}
```

## Provision Progress

The `provision_progress` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `provisioner`: the type of provisioner
- `output`: the output log from the provisioner

One `provision_progress` message is output for each log line received from the provisioner.

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: (local-exec): Executing: [\"/bin/sh\" \"-c\" \"sleep 10 && exit 1\"]",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T16:38:43.997869-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "provisioner": "local-exec",
    "output": "Executing: [\"/bin/sh\" \"-c\" \"sleep 10 && exit 1\"]"
  },
  "type": "provision_progress"
}
```

## Provision Complete

The `provision_complete` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `provisioner`: the type of provisioner

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: (local-exec) Provisioning complete",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-17T09:34:06.239043-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "provisioner": "local-exec"
  },
  "type": "provision_complete"
}
```

## Provision Errored

The `provision_errored` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `provisioner`: the type of provisioner

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: (local-exec) Provisioning errored",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T16:38:54.013572-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "provisioner": "local-exec"
  },
  "type": "provision_errored"
}
```

## Refresh Start

The `refresh_start` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `id_key` and `id_value`: a key/value pair used to identify this instance of the resource

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: Refreshing state... [id=1971614370559474622]",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T14:18:06.508915-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "id_key": "id",
    "id_value": "1971614370559474622"
  },
  "type": "refresh_start"
}
```

## Refresh Complete

The `refresh_complete` message `hook` object has the following keys:

- `resource`: a [`resource` object](#resource-object) identifying the resource
- `id_key` and `id_value`: a key/value pair used to identify this instance of the resource

### Example

```json
{
  "@level": "info",
  "@message": "null_resource.none[0]: Refresh complete [id=1971614370559474622]",
  "@module": "terraform.ui",
  "@timestamp": "2021-03-26T14:18:06.509371-04:00",
  "hook": {
    "resource": {
      "addr": "null_resource.none[0]",
      "module": "",
      "resource": "null_resource.none[0]",
      "implied_provider": "null",
      "resource_type": "null_resource",
      "resource_name": "none",
      "resource_key": 0
    },
    "id_key": "id",
    "id_value": "1971614370559474622"
  },
  "type": "refresh_complete"
}
```

## Resource Object

The `resource` object is a decomposed structure representing a resource address in configuration, which is used to identify which resource a given message is associated with. The object has the following keys:

- `addr`: the full unique address of the resource as a string
- `module`: the address of the module containing the resource, in the form `module.foo.module.bar`, or an empty string for a root module resource
- `resource`: the module-relative address, which is identical to `addr` for root module resources
- `resource_type`: the type of resource being addressed
- `resource_name`: the name label for the resource
- `resource_key`: the address key (`count` or `for_each` value), or `null` if the neither are used
- `implied_provider`: the provider type implied by the resource type; this may not reflect the resource's provider if provider aliases are used

### Example

```json
{
  "addr": "module.pets.random_pet.pet[\"friend\"]",
  "module": "module.pets",
  "resource": "random_pet.pet[\"friend\"]",
  "implied_provider": "random",
  "resource_type": "random_pet",
  "resource_name": "pet",
  "resource_key": "friend"
}
```