Amazon EC2 - cloud-init 25.1.2 documentation (original) (raw)
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The EC2 datasource is the oldest and most widely used datasource thatcloud-init supports. This datasource interacts with a magic IP provided to the instance by the cloud provider (typically this IP is169.254.169.254). At this IP a http server is provided to the instance so that the instance can make calls to get instance user-data and instance-data.
The instance metadata service is accessible via the following URL:
GET http://169.254.169.254/2009-04-04/meta-data/ ami-id ami-launch-index ami-manifest-path block-device-mapping/ hostname instance-id instance-type local-hostname local-ipv4 placement/ public-hostname public-ipv4 public-keys/ reservation-id security-groups
User-data is accessible via the following URL:
GET http://169.254.169.254/2009-04-04/user-data 1234,fred,reboot,true | 4512,jimbo, | 173,,,
Note that there are multiple EC2 instance metadata service versions of this data provided to instances. Cloud-init attempts to use the most recent API version it supports in order to get the latest API features and instance-data. If a given API version is not exposed to the instance, those API features will be unavailable to the instance.
| EC2 version | supported instance-data/feature |
|---|---|
| 2021-03-23 | Required for Instance tag support. This feature must be enabled individually on each instance. See theEC2 tags user guide. |
| 2016-09-02 | Required for secondary IP address support. |
| 2009-04-04 | Minimum supports EC2 API version for meta-data and user-data. |
To see which versions are supported by your cloud provider use the following URL:
GET http://169.254.169.254/ 1.0 2007-01-19 2007-03-01 2007-08-29 2007-10-10 2007-12-15 2008-02-01 2008-09-01 2009-04-04 ... latest
Configuration settings¶
The following configuration can be set for the datasource in system configuration (in /etc/cloud/cloud.cfg or/etc/cloud/cloud.cfg.d/).
The settings that may be configured are:
metadata_urls¶
This list of URLs will be searched for an EC2 instance metadata service. The first entry that successfully returns a 200 response for<url>/<version>/meta-data/instance-id will be selected.
Default: ['http://169.254.169.254', 'http://[fd00:ec2::254]','http://instance-data.:8773'].
max_wait¶
The maximum amount of clock time in seconds that should be spent searchingmetadata_urls. A value less than zero will result in only one request being made, to the first in the list.
Default: 120
timeout¶
The timeout value provided to urlopen for each individual http request. This is used both when selecting a metadata_url and when crawling the instance metadata service.
Default: 50
apply_full_imds_network_config¶
Boolean (default: True) to allow cloud-init to configure any secondary NICs and secondary IPs described by the instance metadata service. All network interfaces are configured with DHCP (v4) to obtain a primary IPv4 address and route. Interfaces which have a non-empty ipv6s list will also enable DHCPv6 to obtain a primary IPv6 address and route. The DHCP response (v4 and v6) return an IP that matches the first element of local-ipv4s andipv6s lists respectively. All additional values (secondary addresses) in the static IP lists will be added to the interface.
An example configuration with the default values is provided below:
datasource: Ec2: metadata_urls: ["http://169.254.169.254:80", "http://instance-data:8773"] max_wait: 120 timeout: 50 apply_full_imds_network_config: true
Notes¶
- There are 2 types of EC2 instances, network-wise: Virtual Private Cloud (VPC) ones and Classic ones (also known as non-VPC). One major difference between them is that Classic instances have their MAC address changed on stop/restart operations, so
cloud-initwill recreate the network config file for EC2 Classic instances every boot. On VPC instances this file is generated only on the first boot of the instance. The check for the instance type is performed byis_classic_instance()method.- For EC2 instances with multiple network interfaces (NICs) attached, DHCP4 will be enabled to obtain the primary private IPv4 address of those NICs. Wherever DHCP4 or DHCP6 is enabled for a NIC, a DHCP route-metric will be added with the value of
<device-number + 1> * 100to ensure DHCP routes on the primary NIC are preferred to any secondary NICs. For example: the primary NIC will have a DHCP route-metric of 100, the next NIC will have 200.- For EC2 instances with multiple NICs, policy-based routing will be configured on secondary NICs / secondary IPs to ensure outgoing packets are routed via the correct interface. This network configuration is only applied on distros using Netplan and at first boot only but it can be configured to be applied on every boot and when NICs are hotplugged, see Events and updates.