Scenarios

ECS metadata includes basic information of an ECS on the cloud platform, such as the ECS ID, hostname, and network information. ECS metadata can be obtained using either OpenStack or EC2 compatible APIs, as shown in Table 1. The following describes the URI and methods of using the supported ECS metadata.

Notes

If the metadata contains sensitive data, take appropriate measures to protect the sensitive data, for example, controlling access permissions and encrypting the data.

Perform the following configuration on the firewall:

Windows
If you need to assign permissions only to the administrator to access custom data, enable the firewall as an administrator and run the following commands in PowerShell:

PS C:\>$RejectPrincipal = New-Object -TypeName System.Security.Principal.NTAccount ("Everyone")

PS C:\>$RejectPrincipalSID = $RejectPrincipal.Translate([System.Security.Principal.SecurityIdentifier]).Value

PS C:\>$ExceptPrincipal = New-Object -TypeName System.Security.Principal.NTAccount ("Administrator")

PS C:\>$ExceptPrincipalSID = $ExceptPrincipal.Translate([System.Security.Principal.SecurityIdentifier]).Value

PS C:\>$PrincipalSDDL = "O:LSD:(D;;CC;;;$ExceptPrincipalSID)(A;;CC;;;$RejectPrincipalSID)"

PS C:\>New-NetFirewallRule -DisplayName "Reject metadata service for $($RejectPrincipal.Value), exception: $($ExceptPrincipal.Value)" -Action block -Direction out -Protocol TCP -RemoteAddress 169.254.169.254 -LocalUser $PrincipalSDDL
Linux
If you need to assign permissions only to user root to access custom data, run the following command as user root:

iptables --append OUTPUT --proto tcp --destination 169.254.169.254 --match owner ! --uid-owner root --jump REJECT

ECS Metadata Types

Table 1 does not contain the following metadata items: ami-id, ami-launch-index, ami-manifest-path, block-device-mapping/, instance-action, instance-id, reservation-id, ramdisk-id, and kernel-id. These metadata items are meaningless and are not recommended.

**Table 1** ECS metadata types
Metadata Type	Metadata Item	Description
OpenStack	/meta_data.json	Displays ECS metadata. For the key fields in the ECS metadata, see Table 2.
OpenStack	/password	Displays the password for logging in to an ECS. This metadata is used by Cloudbase-Init to store ciphertext passwords during initialization of key-pair-authenticated Windows ECSs.
OpenStack	/user_data	Displays ECS user data. This metadata allows you to specify scripts and configuration files for initializing ECSs. For details, see Passing User Data to ECSs. For password-authenticated Linux ECSs, this metadata is used to save password injection scripts.
OpenStack	/network_data.json	Displays ECS network information.
OpenStack	/securitykey	Obtains temporary AKs and SKs. Before enabling an ECS to obtain a temporary AK and SK, make sure that the op_svc_ecs account has been authorized on IAM and that the desired ECS resources have been authorized for management.
EC2-compatible	/meta-data/hostname	Displays the name of the host accommodating an ECS. To remove the suffix .novalocal from an ECS, see: Is an ECS Hostname with Suffix .novalocal Normal?
EC2-compatible	/meta-data/local-hostname	The meaning of this field is the same as that of hostname.
EC2-compatible	/meta-data/public-hostname	The meaning of this field is the same as that of hostname.
EC2-compatible	/meta-data/instance-type	Displays an ECS flavor.
EC2-compatible	/meta-data/local-ipv4	Displays the fixed IP address of an ECS. If there are multiple NICs, only the IP address of the primary NIC is displayed.
EC2-compatible	/meta-data/placement/availability-zone	Displays the AZ accommodating an ECS.
EC2-compatible	/meta-data/public-ipv4	Displays the EIP bound to the ECS. If there are multiple NICs, only the EIP of the primary NIC is displayed.
EC2-compatible	/meta-data/public-keys/0/openssh-key	Displays the public key of an ECS.
EC2-compatible	/user-data	Displays ECS user data.
EC2-compatible	/meta-data/security-groups	Displays the security group of an ECS.

**Table 2** Metadata key fields
Parameter	Type	Description
uuid	String	Specifies an ECS ID.
availability_zone	String	Specifies the AZ where an ECS locates.
meta	Dict	Specifies the metadata information, including the image name, image ID, and VPC ID.
hostname	String	Specifies the name of the host accommodating an ECS. To remove the suffix .novalocal from an ECS, see: Is an ECS Hostname with Suffix .novalocal Normal?

Prerequisites

The target ECS has been logged in.
Security group rules in the outbound direction meet the following requirements:
- Protocol: TCP
- Port: 80
- Destination: 169.254.0.0/16
If you use the default security group rules for the outbound direction, the metadata can be accessed because the default rules meet the preceding requirements. For details about the default security group rules for the outbound direction, see Default Security Group and Rules.

Metadata (OpenStack Metadata API)

This API is used to query ECS metadata.

URI
/169.254.169.254/openstack/latest/meta_data.json
Usage method
Supports GET requests.

Example

To use cURL to view Linux ECS metadata, run the following command:

curl http://169.254.169.254/openstack/latest/meta_data.json

To use Invoke-RestMethod to view Windows ECS metadata, run the following command:

Invoke-RestMethod http://169.254.169.254/openstack/latest/meta_data.json | ConvertTo-Json

{
    "random_seed": "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",
    "uuid": "ca9e8b7c-f2be-4b6d-a639-f10b4d994d04",
    "availability_zone": "lt-test-1c",
    "hostname": "ecs-ddd4.novalocal",
    "launch_index": 0,
    "meta": {
        "metering.image_id": "3a64bd37-955e-40cd-ab9e-129db56bc05d",
        "metering.imagetype": "gold",
        "metering.resourcespeccode": "s3.medium.2.linux",
        "image_name": "CentOS 7.6 64bit",
        "metering.resourcetype": "1", 
        "vpc_id": "3b6c201f-aeb3-4bce-b841-64756e66cb49",
        "os_bit": "64",
        "cascaded.instance_extrainfo": "pcibridge:1",
        "os_type": "Linux",
        "charging_mode": "0"
    },
    "project_id": "6e8b0c94265645f39c5abbe63c4113c6",
    "name": "ecs-ddd4"
}

User Data (OpenStack Metadata API)

This API is used to query ECS user data. The value is configured only when you create an ECS. It cannot be changed after the configuration.

URI
/169.254.169.254/openstack/latest/user_data
Usage method
Supports GET requests.

Example

Linux:

curl http://169.254.169.254/openstack/latest/user_data

Windows:

Invoke-RestMethod http://169.254.169.254/openstack/latest/user_data

ICAgICAgDQoiQSBjbG91ZCBkb2VzIG5vdCBrbm93IHdoeSBpdCBtb3ZlcyBpbiBqdXN0IHN1Y2ggYSBkaXJlY3Rpb24gYW5kIGF0IHN1Y2ggYSBzcGVlZC4uLkl0IGZlZWxzIGFuIGltcHVsc2lvbi4uLnRoaXMgaXMgdGhlIHBsYWNlIHRvIGdvIG5vdy4gQnV0IHRoZSBza3kga25vd3MgdGhlIHJlYXNvbnMgYW5kIHRoZSBwYXR0ZXJucyBiZWhpbmQgYWxsIGNsb3VkcywgYW5kIHlvdSB3aWxsIGtub3csIHRvbywgd2hlbiB5b3UgbGlmdCB5b3Vyc2VsZiBoaWdoIGVub3VnaCB0byBzZWUgYmV5b25kIGhvcml6b25zLiINCg0KLVJpY2hhcmQgQmFjaA==

If user data was not passed to the ECS during ECS creation, the query result is 404.

Figure 1 404 Not Found
Click to enlarge

Network Data (OpenStack Metadata API)

This API is used to query information about all NICs attached to an ECS, including their DNS server addresses, network bandwidth, IDs, private IP addresses, EIPs, and MAC addresses.

URI
/openstack/latest/network_data.json
Usage method
Supports GET requests.

Example

instance_max_bandwidth and instance_min_bandwidth are in the unit of Mbit/s. If the value is -1, the bandwidth is not limited.

Linux:

curl http://169.254.169.254/openstack/latest/network_data.json

Windows:

Invoke-RestMethod http://169.254.169.254/openstack/latest/network_data.json | ConvertTo-Json

{
    "services": [{
        "type": "dns",
        "address": "xxx.xx.x.x"
    },
    {
        "type": "dns",
        "address": "100.125.21.250"
    }],
    "qos":{
        "instance_min_bandwidth": 100,
        "instance_max_bandwidth": 500
    },
    "networks": [{
        "network_id": "67dc10ce-441f-4592-9a80-cc709f6436e7",
        "type": "ipv4_dhcp",
        "link": "tap68a9272d-71",
        "id": "network0"
    }],
    "links": [{
        "vif_id": "68a9272d-7152-4ae7-a138-3ef53af669e7",
        "ethernet_mac_address": "fa:16:3e:f7:c1:47",
        "mtu": null,
        "type": "cascading",
        "id": "tap68a9272d-71"
    }]
}

Security Key (OpenStack Metadata API)

This API is used to obtain temporary AKs and SKs.

If an ECS needs to obtain a temporary AK and SK, go to the ECS details page, and configure Agency for the ECS in the Management Information area so that the ECS is authorized on IAM.
The validity period of a temporary AK and SK is one hour. The temporary AK and SK are updated 10 minutes ahead of the expiration time. During the 10 minutes, both the new and old temporary AKs and SKs can be used.
When using temporary AKs and SKs, add 'X-Security-Token':{securitytoken} in the message header. securitytoken is the value returned when a call is made to the API.

URI
/openstack/latest/securitykey
Usage method
Supports GET requests.
Examples
Linux:

curl http://169.254.169.254/openstack/latest/securitykey

Windows:

Invoke-RestMethod http://169.254.169.254/openstack/latest/securitykey

User Data (EC2 Compatible API)

This API is used to query ECS user data. The value is configured only when you create an ECS. It cannot be changed after the configuration.

URI
/169.254.169.254/latest/user-data
Usage method
Supports GET requests.

Example

Linux:

curl http://169.254.169.254/latest/user-data

Windows:

Invoke-RestMethod http://169.254.169.254/latest/user-data

ICAgICAgDQoiQSBjbG91ZCBkb2VzIG5vdCBrbm93IHdoeSBpdCBtb3ZlcyBpbiBqdXN0IHN1Y2ggYSBkaXJlY3Rpb24gYW5kIGF0IHN1Y2ggYSBzcGVlZC4uLkl0IGZlZWxzIGFuIGltcHVsc2lvbi4uLnRoaXMgaXMgdGhlIHBsYWNlIHRvIGdvIG5vdy4gQnV0IHRoZSBza3kga25vd3MgdGhlIHJlYXNvbnMgYW5kIHRoZSBwYXR0ZXJucyBiZWhpbmQgYWxsIGNsb3VkcywgYW5kIHlvdSB3aWxsIGtub3csIHRvbywgd2hlbiB5b3UgbGlmdCB5b3Vyc2VsZiBoaWdoIGVub3VnaCB0byBzZWUgYmV5b25kIGhvcml6b25zLiINCg0KLVJpY2hhcmQgQmFjaA==

Hostname (EC2 Compatible API)

This API is used to query the name of the host accommodating an ECS. The .novalocal suffix will be added later.

URI
/169.254.169.254/latest/meta-data/hostname
Usage method
Supports GET requests.
Example
Linux:

curl http://169.254.169.254/latest/meta-data/hostname

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/hostname
```
vm-test.novalocal
```

Instance Type (EC2 Compatible API)

This API is used to query an ECS flavor.

URI
/169.254.169.254/latest/meta-data/instance-type
Usage method
Supports GET requests.
Example
Linux:

curl http://169.254.169.254/latest/meta-data/instance-type

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/instance-type
```
s3.medium.2
```

Local IPv4 (EC2 Compatible API)

This API is used to query the fixed IP address of an ECS. If there are multiple NICs, only the IP address of the primary NIC is displayed.

URI
/169.254.169.254/latest/meta-data/local-ipv4
Usage method
Supports GET requests.
Example
Linux:

curl http://169.254.169.254/latest/meta-data/local-ipv4

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/local-ipv4
```
192.1.1.2
```

Availability Zone (EC2 Compatible API)

This API is used to query the AZ accommodating an ECS.

URI
/169.254.169.254/latest/meta-data/placement/availability-zone
Usage method
Supports GET requests.
Example
Linux:

curl http://169.254.169.254/latest/meta-data/placement/availability-zone

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/placement/availability-zone
```
az1.dc1
```

Public IPv4 (EC2 Compatible API)

This API is used to query the EIP bound to an ECS. If there are multiple NICs, only the EIP of the primary NIC is displayed.

URI
/169.254.169.254/latest/meta-data/public-ipv4
Usage method
Supports GET requests.
Example
Linux:

curl http://169.254.169.254/latest/meta-data/public-ipv4

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/public-ipv4
```
46.1.1.2
```

Public Keys (EC2 Compatible API)

This API is used to query the public key of an ECS.

URI
/169.254.169.254/latest/meta-data/public-keys/0/openssh-key
Usage method
Supports GET requests.

Example

Linux:

curl http://169.254.169.254/latest/meta-data/public-keys/0/openssh-key

Windows:

Invoke-RestMethod http://169.254.169.254/latest/meta-data/public-keys/0/openssh-key

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDI5Fw5k8Fgzajn1zJwLoV3+wMP+6CyvsSiIc/hioggSnYu/AD0Yqm8vVO0kWlun1rFbdO+QUZKyVr/OPUjQSw4SRh4qsTKf/+eFoWTjplFvd1WCBZzS/WRenxIwR00KkczHSJro763+wYcwKieb4eKRxaQoQvoFgVjLBULXAjH4eKoKTVNtMXAvPP9aMy2SLgsJNtMb9ArfziAiblQynq7UIfLnN3VclzPeiWrqtzjyOp6CPUXnL0lVPTvbLe8sUteBsJZwlL6K4i+Y0lf3ryqnmQgC21yW4Dzu+kwk8FVT2MgWkCwiZd8gQ/+uJzrJFyMfUOBIklOBfuUENIJUhAB Generated-by-Nova

Helpful Links

Why Can't My Linux ECS Obtain Metadata?

Obtaining Metadata

Scenarios

Notes

ECS Metadata Types

Prerequisites

Metadata (OpenStack Metadata API)

User Data (OpenStack Metadata API)

Network Data (OpenStack Metadata API)

Security Key (OpenStack Metadata API)

User Data (EC2 Compatible API)

Hostname (EC2 Compatible API)

Instance Type (EC2 Compatible API)

Local IPv4 (EC2 Compatible API)

Availability Zone (EC2 Compatible API)

Public IPv4 (EC2 Compatible API)

Public Keys (EC2 Compatible API)

Helpful Links