.. _instance_metadata:

*****************
Instance Metadata
*****************

.. toctree::
  :maxdepth: 1
  :hidden:

  kernel-cmdline.rst

What is instance-data?
========================

Each cloud provider presents unique
configuration metadata to a launched cloud instance. Cloud-init
crawls this metadata and then caches and exposes this information
as a standarized and versioned JSON object known as instance-data.
This instance-data may then be
queried or later used by cloud-init in templated configuration and scripts.

An example of a small subset of instance-data on a launched EC2 instance:

.. code-block:: json

  {
    "v1": {
      "cloud_name": "aws",
      "distro": "ubuntu",
      "distro_release": "jammy",
      "distro_version": "22.04",
      "instance_id": "i-06b5687b4d7b8595d",
      "machine": "x86_64",
      "platform": "ec2",
      "python_version": "3.10.4",
      "region": "us-east-2",
      "variant": "ubuntu"
    }
  }


Discovery
=========

One way to easily explore what instance-data variables are available on
your machine is to use the :ref:`cloud-init query<cli_query>` tool.
Warnings or exceptions will be raised on invalid instance-data keys,
paths or invalid syntax.

The **query** command also publishes ``userdata`` and ``vendordata`` keys to
the root user which will contain the decoded user and vendor data provided to
this instance. Non-root users referencing userdata or vendordata keys will
see only redacted values.

.. note::
  To save time designing a user-data template for a specific cloud's
  instance-data.json, use the 'render' cloud-init command on an
  instance booted on your favorite cloud. See :ref:`cli_devel` for more
  information.

Using instance-data
===================

Instance-data can be used in:

* :ref:`User-data scripts<topics/format:User-Data Script>`
* :ref:`Cloud-config data<topics/format:Cloud Config Data>`
* :ref:`Base configuration<configuration>`
* Command line interface via **cloud-init query** or
  **cloud-init devel render**

The aforementioned configuration sources support jinja template rendering.
When the first line of the provided configuration begins with
**## template: jinja**, cloud-init will use jinja to render that file.
Any instance-data variables are surfaced as jinja template
variables.

.. note::
  Trying to reference jinja variables that don't exist in instance-data
  will result in warnings in ``/var/log/cloud-init.log`` and the following
  string in your rendered user-data:
  ``CI_MISSING_JINJA_VAR/<your_varname>``.

Sensitive data such as user passwords may be contained in
instance-data. Cloud-init separates this sensitive data such that
is it only readable by root. In the case that a non-root user attempts
to read sensitive instance-data, they will receive redacted data or same
warnings and text that occur if a variable does not exist.

Example Usage
-------------

Cloud config with instance-data
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: yaml

  ## template: jinja
  #cloud-config
  runcmd:
      - echo 'EC2 public hostname allocated to instance: {{
        ds.meta_data.public_hostname }}' > /tmp/instance_metadata
      - echo 'EC2 availability zone: {{ v1.availability_zone }}' >>
        /tmp/instance_metadata
      - curl -X POST -d '{"hostname": "{{ds.meta_data.public_hostname }}",
        "availability-zone": "{{ v1.availability_zone }}"}'
        https://example.com

User-data script with instance-data
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: jinja

   ## template: jinja
   #!/bin/bash
   {% if v1.region == 'us-east-2' -%}
   echo 'Installing custom proxies for {{ v1.region }}
   sudo apt-get install my-xtra-fast-stack
   {%- endif %}
   ...

CLI discovery of instance-data
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: shell-session

  # List all instance-data keys and values as root user
  % sudo cloud-init query --all
  {...}

  # List all top-level instance-data keys available
  % cloud-init query --list-keys

  # Introspect nested keys on an object
  % cloud-init query -f "{{ds.keys()}}"
  dict_keys(['meta_data', '_doc'])

  # Failure to reference valid dot-delimited key path on a known top-level key
  % cloud-init query v1.not_here
  ERROR: instance-data 'v1' has no 'not_here'

  # Test expected value using valid instance-data key path
  % cloud-init query -f "My AMI: {{ds.meta_data.ami_id}}"
  My AMI: ami-0fecc35d3c8ba8d60

  # The --format command renders jinja templates, this can also be used
  # to develop and test jinja template constructs
  % cat > test-templating.yaml <<EOF
    {% for val in ds.meta_data.keys() %}
    - {{ val }}
    {% endfor %}
    EOF
  % cloud-init query --format="$( cat test-templating.yaml )"
  - instance_id
  - dsmode
  - local_hostname

Reference
=========

Storage Locations
-----------------
* ``/run/cloud-init/instance-data.json``: world-readable json containing
  standardized keys, sensitive keys redacted
* ``/run/cloud-init/instance-data-sensitive.json``: root-readable unredacted
  json blob

Format of instance-data.json
----------------------------

Top-level keys:

* **base64_encoded_keys**: A list of forward-slash delimited key paths into
  the instance-data.json object whose value is base64encoded for json
  compatibility. Values at these paths should be decoded to get the original
  value.

* **sensitive_keys**: A list of forward-slash delimited key paths into
  the instance-data.json object whose value is considered by the datasource as
  'security sensitive'. Only the keys listed here will be redacted from
  instance-data.json for non-root users.

* **merged_cfg**: Merged cloud-init :ref:`base_config_reference` from
  `/etc/cloud/cloud.cfg` and  `/etc/cloud/cloud-cfg.d`. Values under this key
  could contain sensitive information such as passwords, so it is included in
  the **sensitive-keys** list which is only readable by root.

* **ds**: Datasource-specific metadata crawled for the specific cloud
  platform. It should closely represent the structure of the cloud metadata
  crawled. The structure of content and details provided are entirely
  cloud-dependent. Mileage will vary depending on what the cloud exposes.
  The content exposed under the 'ds' key is currently **experimental** and
  expected to change slightly in the upcoming cloud-init release.

* **sys_info**: Information about the underlying os, python, architecture and
  kernel. This represents the data collected by `cloudinit.util.system_info`.

* **v1**: Standardized cloud-init metadata keys, these keys are guaranteed to
  exist on all cloud platforms. They will also retain their current behavior
  and format and will be carried forward even if cloud-init introduces a new
  version of standardized keys with **v2**.

To cut down on keystrokes on the command line, cloud-init also provides
top-level key aliases for any standardized ``v#`` keys present. The preceding
``v1`` is not required of ``v1.var_name`` These aliases will represent the
value of the highest versioned standard key. For example, ``cloud_name``
value will be ``v2.cloud_name`` if both ``v1`` and ``v2`` keys are present in
instance-data.json.

cloud-init also provides jinja-safe key aliases for any instance-data
keys which contain jinja operator characters such as +, -, ., /, etc. Any
jinja operator will be replaced with underscores in the jinja-safe key
alias. This allows for cloud-init templates to use aliased variable
references which allow for jinja's dot-notation reference such as
``{{ ds.v1_0.my_safe_key }}`` instead of ``{{ ds["v1.0"]["my/safe-key"] }}``.

The standardized keys present:

v1._beta_keys
-------------
List of standardized keys still in 'beta'. The format, intent or presence of
these keys can change. Do not consider them production-ready.

Example output:

- [subplatform]

v1.cloud_name
-------------
Where possible this will indicate the 'name' of the cloud the system is running
on. This is different than the 'platform' item. For example, the cloud name of
Amazon Web Services is 'aws', while the platform is 'ec2'.

If determining a specific name is not possible or provided in meta-data, then
this filed may contain the same content as 'platform'.

Example output:

- aws
- openstack
- azure
- configdrive
- nocloud
- ovf

v1.distro, v1.distro_version, v1.distro_release
-----------------------------------------------
This shall be the distro name, version and release as determined by
`cloudinit.util.get_linux_distro`.

Example output:

- alpine, 3.12.0, ''
- centos, 7.5, core
- debian, 9, stretch
- freebsd, 12.0-release-p10,
- opensuse, 42.3, x86_64
- opensuse-tumbleweed, 20180920, x86_64
- redhat, 7.5, 'maipo'
- sles, 12.3, x86_64
- ubuntu, 20.04, focal

v1.instance_id
--------------
Unique instance_id allocated by the cloud.

Examples output:

- i-<hash>

v1.kernel_release
-----------------
This shall be the running kernel `uname -r`

Example output:

- 5.3.0-1010-aws

v1.local_hostname
-----------------
The internal or local hostname of the system.

Examples output:

- ip-10-41-41-70
- <user-provided-hostname>

v1.machine
----------
This shall be the running cpu machine architecture `uname -m`

Example output:

- x86_64
- i686
- ppc64le
- s390x

v1.platform
-------------
An attempt to identify the cloud platform instance that the system is running
on.

Examples output:

- ec2
- openstack
- lxd
- gce
- nocloud
- ovf

v1.subplatform
--------------
Additional platform details describing the specific source or type of metadata
used. The format of subplatform will be:

``<subplatform_type> (<url_file_or_dev_path>)``

Examples output:

- metadata (http://168.254.169.254)
- seed-dir (/path/to/seed-dir/)
- config-disk (/dev/cd0)
- configdrive (/dev/sr0)

v1.public_ssh_keys
------------------
A list of SSH keys provided to the instance by the datasource metadata.

Examples output:

- ['ssh-rsa AA...', ...]

v1.python_version
-----------------
The version of python that is running cloud-init as determined by
`cloudinit.util.system_info`

Example output:

- 3.7.6

v1.region
---------
The physical region/data center in which the instance is deployed.

Examples output:

- us-east-2

v1.availability_zone
--------------------
The physical availability zone in which the instance is deployed.

Examples output:

- us-east-2b
- nova
- null

Example Output
--------------

Below is an example of ``/run/cloud-init/instance-data-sensitive.json`` on an
EC2 instance:

.. sourcecode:: json

  {
   "_beta_keys": [
    "subplatform"
   ],
   "availability_zone": "us-east-1b",
   "base64_encoded_keys": [],
   "merged_cfg": {
    "_doc": "Merged cloud-init base config from /etc/cloud/cloud.cfg and /etc/cloud/cloud.cfg.d/",
    "_log": [
     "[loggers]\nkeys=root,cloudinit\n\n[handlers]\nkeys=consoleHandler,cloudLogHandler\n\n[formatters]\nkeys=simpleFormatter,arg0Formatter\n\n[logger_root]\nlevel=DEBUG\nhandlers=consoleHandler,cloudLogHandler\n\n[logger_cloudinit]\nlevel=DEBUG\nqualname=cloudinit\nhandlers=\npropagate=1\n\n[handler_consoleHandler]\nclass=StreamHandler\nlevel=WARNING\nformatter=arg0Formatter\nargs=(sys.stderr,)\n\n[formatter_arg0Formatter]\nformat=%(asctime)s - %(filename)s[%(levelname)s]: %(message)s\n\n[formatter_simpleFormatter]\nformat=[CLOUDINIT] %(filename)s[%(levelname)s]: %(message)s\n",
     "[handler_cloudLogHandler]\nclass=FileHandler\nlevel=DEBUG\nformatter=arg0Formatter\nargs=('/var/log/cloud-init.log',)\n",
     "[handler_cloudLogHandler]\nclass=handlers.SysLogHandler\nlevel=DEBUG\nformatter=simpleFormatter\nargs=(\"/dev/log\", handlers.SysLogHandler.LOG_USER)\n"
    ],
    "cloud_config_modules": [
     "snap",
     "ssh-import-id",
     "locale",
     "set-passwords",
     "grub-dpkg",
     "apt-pipelining",
     "apt-configure",
     "ubuntu-advantage",
     "ntp",
     "timezone",
     "disable-ec2-metadata",
     "runcmd",
     "byobu"
    ],
    "cloud_final_modules": [
     "package-update-upgrade-install",
     "fan",
     "landscape",
     "lxd",
     "ubuntu-drivers",
     "puppet",
     "chef",
     "mcollective",
     "salt-minion",
     "rightscale_userdata",
     "scripts-vendor",
     "scripts-per-once",
     "scripts-per-boot",
     "scripts-per-instance",
     "scripts-user",
     "ssh-authkey-fingerprints",
     "keys-to-console",
     "phone-home",
     "final-message",
     "power-state-change"
    ],
    "cloud_init_modules": [
     "migrator",
     "seed_random",
     "bootcmd",
     "write-files",
     "growpart",
     "resizefs",
     "disk_setup",
     "mounts",
     "set_hostname",
     "update_hostname",
     "update_etc_hosts",
     "ca-certs",
     "rsyslog",
     "users-groups",
     "ssh"
    ],
    "datasource_list": [
     "Ec2",
     "None"
    ],
    "def_log_file": "/var/log/cloud-init.log",
    "disable_root": true,
    "log_cfgs": [
     [
      "[loggers]\nkeys=root,cloudinit\n\n[handlers]\nkeys=consoleHandler,cloudLogHandler\n\n[formatters]\nkeys=simpleFormatter,arg0Formatter\n\n[logger_root]\nlevel=DEBUG\nhandlers=consoleHandler,cloudLogHandler\n\n[logger_cloudinit]\nlevel=DEBUG\nqualname=cloudinit\nhandlers=\npropagate=1\n\n[handler_consoleHandler]\nclass=StreamHandler\nlevel=WARNING\nformatter=arg0Formatter\nargs=(sys.stderr,)\n\n[formatter_arg0Formatter]\nformat=%(asctime)s - %(filename)s[%(levelname)s]: %(message)s\n\n[formatter_simpleFormatter]\nformat=[CLOUDINIT] %(filename)s[%(levelname)s]: %(message)s\n",
      "[handler_cloudLogHandler]\nclass=FileHandler\nlevel=DEBUG\nformatter=arg0Formatter\nargs=('/var/log/cloud-init.log',)\n"
     ]
    ],
    "output": {
     "all": "| tee -a /var/log/cloud-init-output.log"
    },
    "preserve_hostname": false,
    "syslog_fix_perms": [
     "syslog:adm",
     "root:adm",
     "root:wheel",
     "root:root"
    ],
    "users": [
     "default"
    ],
    "vendor_data": {
     "enabled": true,
     "prefix": []
    }
   },
   "cloud_name": "aws",
   "distro": "ubuntu",
   "distro_release": "focal",
   "distro_version": "20.04",
   "ds": {
    "_doc": "EXPERIMENTAL: The structure and format of content scoped under the 'ds' key may change in subsequent releases of cloud-init.",
    "_metadata_api_version": "2016-09-02",
    "dynamic": {
     "instance_identity": {
      "document": {
       "accountId": "329910648901",
       "architecture": "x86_64",
       "availabilityZone": "us-east-1b",
       "billingProducts": null,
       "devpayProductCodes": null,
       "imageId": "ami-02e8aa396f8be3b6d",
       "instanceId": "i-0929128ff2f73a2f1",
       "instanceType": "t2.micro",
       "kernelId": null,
       "marketplaceProductCodes": null,
       "pendingTime": "2020-02-27T20:46:18Z",
       "privateIp": "172.31.81.43",
       "ramdiskId": null,
       "region": "us-east-1",
       "version": "2017-09-30"
      },
      "pkcs7": [
       "MIAGCSqGSIb3DQ...",
       "REDACTED",
       "AhQUgq0iPWqPTVnT96tZE6L1XjjLHQAAAAAAAA=="
      ],
      "rsa2048": [
       "MIAGCSqGSIb...",
       "REDACTED",
       "clYQvuE45xXm7Yreg3QtQbrP//owl1eZHj6s350AAAAAAAA="
      ],
      "signature": [
       "dA+QV+LLCWCRNddnrKleYmh2GvYo+t8urDkdgmDSsPi",
       "REDACTED",
       "kDT4ygyJLFkd3b4qjAs="
      ]
     }
    },
    "meta_data": {
     "ami_id": "ami-02e8aa396f8be3b6d",
     "ami_launch_index": "0",
     "ami_manifest_path": "(unknown)",
     "block_device_mapping": {
      "ami": "/dev/sda1",
      "root": "/dev/sda1"
     },
     "hostname": "ip-172-31-81-43.ec2.internal",
     "instance_action": "none",
     "instance_id": "i-0929128ff2f73a2f1",
     "instance_type": "t2.micro",
     "local_hostname": "ip-172-31-81-43.ec2.internal",
     "local_ipv4": "172.31.81.43",
     "mac": "12:7e:c9:93:29:af",
     "metrics": {
      "vhostmd": "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
     },
     "network": {
      "interfaces": {
       "macs": {
        "12:7e:c9:93:29:af": {
         "device_number": "0",
         "interface_id": "eni-0c07a0474339b801d",
         "ipv4_associations": {
          "3.89.187.177": "172.31.81.43"
         },
         "local_hostname": "ip-172-31-81-43.ec2.internal",
         "local_ipv4s": "172.31.81.43",
         "mac": "12:7e:c9:93:29:af",
         "owner_id": "329910648901",
         "public_hostname": "ec2-3-89-187-177.compute-1.amazonaws.com",
         "public_ipv4s": "3.89.187.177",
         "security_group_ids": "sg-0100038b68aa79986",
         "security_groups": "launch-wizard-3",
         "subnet_id": "subnet-04e2d12a",
         "subnet_ipv4_cidr_block": "172.31.80.0/20",
         "vpc_id": "vpc-210b4b5b",
         "vpc_ipv4_cidr_block": "172.31.0.0/16",
         "vpc_ipv4_cidr_blocks": "172.31.0.0/16"
        }
       }
      }
     },
     "placement": {
      "availability_zone": "us-east-1b"
     },
     "profile": "default-hvm",
     "public_hostname": "ec2-3-89-187-177.compute-1.amazonaws.com",
     "public_ipv4": "3.89.187.177",
     "reservation_id": "r-0c481643d15766a02",
     "security_groups": "launch-wizard-3",
     "services": {
      "domain": "amazonaws.com",
      "partition": "aws"
     }
    }
   },
   "instance_id": "i-0929128ff2f73a2f1",
   "kernel_release": "5.3.0-1010-aws",
   "local_hostname": "ip-172-31-81-43",
   "machine": "x86_64",
   "platform": "ec2",
   "public_ssh_keys": [],
   "python_version": "3.7.6",
   "region": "us-east-1",
   "sensitive_keys": [],
   "subplatform": "metadata (http://169.254.169.254)",
   "sys_info": {
    "dist": [
     "ubuntu",
     "20.04",
     "focal"
    ],
    "platform": "Linux-5.3.0-1010-aws-x86_64-with-Ubuntu-20.04-focal",
    "python": "3.7.6",
    "release": "5.3.0-1010-aws",
    "system": "Linux",
    "uname": [
     "Linux",
     "ip-172-31-81-43",
     "5.3.0-1010-aws",
     "#11-Ubuntu SMP Thu Jan 16 07:59:32 UTC 2020",
     "x86_64",
     "x86_64"
    ],
    "variant": "ubuntu"
   },
   "system_platform": "Linux-5.3.0-1010-aws-x86_64-with-Ubuntu-20.04-focal",
   "userdata": "#cloud-config\nssh_import_id: [<my-launchpad-id>]\n...",
   "v1": {
    "_beta_keys": [
     "subplatform"
    ],
    "availability_zone": "us-east-1b",
    "cloud_name": "aws",
    "distro": "ubuntu",
    "distro_release": "focal",
    "distro_version": "20.04",
    "instance_id": "i-0929128ff2f73a2f1",
    "kernel": "5.3.0-1010-aws",
    "local_hostname": "ip-172-31-81-43",
    "machine": "x86_64",
    "platform": "ec2",
    "public_ssh_keys": [],
    "python": "3.7.6",
    "region": "us-east-1",
    "subplatform": "metadata (http://169.254.169.254)",
    "system_platform": "Linux-5.3.0-1010-aws-x86_64-with-Ubuntu-20.04-focal",
    "variant": "ubuntu"
   },
   "variant": "ubuntu",
   "vendordata": ""
  }
