mirror of
https://github.com/linuxkit/linuxkit.git
synced 2025-10-27 04:32:13 +00:00
766e1d95d3
This package handles meta and user data for different cloud and other platforms. It should be easy to extend to new platforms. Currently, it handles GCP metadata and a simple CDROM userdata provider. Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
71 lines
2.1 KiB
Markdown
71 lines
2.1 KiB
Markdown
# Metadata and Userdata handling
|
|
|
|
Most providers offer a mechanism to provide a OS with some additional
|
|
metadata as well as custom userdata. `Metadata` in this context is
|
|
fixed information provided by the provider (e.g. the host
|
|
name). `Userdata` is completely custom data which a user can supply to
|
|
the instance.
|
|
|
|
The [metadata package](../pkg/metadata/) handles both metadata and
|
|
userdata for a number of providers (see below). It abstracts over the
|
|
provider differences by exposing both metadata and userdata in a
|
|
directory hierarchy under `/var/config`. For example, sshd config
|
|
files from the metadata are placed under `/var/config/ssh`.
|
|
|
|
Userdata is assumed to be a single string and the contents will be
|
|
stored under `/var/config/userdata`. If userdata is a json file, the
|
|
contents will be further processed, where different keys cause
|
|
directories to be created and the directories are populated with files. Foer example, the following userdata file:
|
|
```
|
|
{
|
|
"ssh" : {
|
|
"sshd_config" : {
|
|
"perm" : "0600",
|
|
"content": "PermitRootLogin yes\nPasswordAuthentication no"
|
|
}
|
|
},
|
|
"foo" : {
|
|
"bar" : {
|
|
"perm": "0644",
|
|
"content": "foobar"
|
|
},
|
|
"baz" : {
|
|
"perm": "0600",
|
|
"content": "bar"
|
|
}
|
|
}
|
|
}
|
|
```
|
|
will generate the following files:
|
|
```
|
|
/var/config/ssh/sshd_config
|
|
/var/config/foo/bar
|
|
/var/config/foo/baz
|
|
```
|
|
|
|
This hierarchy can then be used by individual containers, who can bind
|
|
mount the config sub-directory into their namespace where it is
|
|
needed.
|
|
|
|
|
|
# Providers
|
|
|
|
Below is a list of supported providers and notes on what is supported. We will add more over time.
|
|
|
|
|
|
## GCP
|
|
|
|
GCP metadata is reached via a well known URL
|
|
(`http://metadata.google.internal/`) and currently
|
|
we extract the hostname and populate the
|
|
`/var/config/ssh/authorized_keys` from metadata. In the future we'll
|
|
add more complete SSH support.
|
|
|
|
GCP userdata is extracted from `/computeMetadata/v1/instance/attributes/userdata`.
|
|
|
|
|
|
## HyperKit
|
|
|
|
HyperKit does not support metadata and userdata is passed in as a single file via a ISO9660 image.
|
|
|