Revision as of 07:59, 27 January 2022

Introduction

Proxmox VE uses a REST like API. The concept is described in [1] (Resource Oriented Architectur - ROA).

We choose JSON as primary data format, and the whole API is formally defined using JSON Schema [2].

You can explore the API documentation at http://pve.proxmox.com/pve-docs/api-viewer/index.html

JSON and JSON Schema

The API use JSON as data format, because it is simple and parse-able by any web browser.

Additionally, we use JSON Schema [2] to formally describe our API. So we can automatically generate the whole API Documentation, and we can verify all parameters and return values.

An great side effect was that we are able to use JSON Schema to produce command line argument parsers automatically. In fact, the REST API and the command line tools use the same code. A small utility called 'pvesh' exposes the whole REST API on the command line.

So here is a summary of the advantage:

easy, human-readable data format (native web browser format)
automatic parameter verification (we can also verify return values)
automatic generation of API documentation
easy way to create command line tools (use the same API)

API Stability & Breakage

Proxmox VE tries to stay API compatible in a major release. For example, an API call that worked with 6.0 should also work with 6.4 but has no guarantee to do so with 7.0.

A breaking change is defined as:

Removing an API endpoint entirely
Moving an API endpoint to a new path. Normally we add the new one already and move the legacy option on the next major version bump.
Removing parameters from an API endpoint
Changing the return type from a non-null type to another type

The following examples are not considered as breaking change:

Changing an endpoint's return type from null to anything else is not considered as breaking change
Adding new parameters
Adding new properties to returned objects
Slight semantic changes, as this is often a requirement for a bugfix, albeit we either try
- to guard those under opt-in parameters
- to mirror the Linux Kernel "never break user-space" principle. I.e., we break it as long as deemed small enough and useful, but we are open for addressing complaints by actual users and find a solution, or switch the behavior back to the previous one.
Adding new API endpoints

API URL

The API uses the HTTPS protocol and the server listens to port 8006. So the base URL for that API is

https://your.server:8006/api2/json/

Parameters can be passed using standard HTTP techniques:

via the URL
using 'x-www-form-urlencoded' content-type for PUT and POST request.

It is possible specify the return format in the URL. Above example uses 'json', but you can use any of the following values:

json: JSON
extjs: JSON variant compatible with ExtJS forms
html: html formatted text - sometimes useful for debugging
text: plain text - sometimes useful for debugging

Please contact use on the development mailing list if you need other data formats.

Authentication

Proxmox VE uses a ticket or token based authentication, all request to the API need to include a ticket inside a Cookie (header) or sending an API token through the Authorization header.

Ticket Cookie

A ticket is a signed random text value with the user and creation time included. Tickets are signed by the cluster-wide authentication key that is rotated once per day.

Additionally, any write (POST/PUT/DELETE) request must include a CSRF prevention token inside the HTTP header. The following examples use the curl command line tool.

Example: Get a New Ticket and the CSRF Prevention Token

Request - warning, command line parameters are visible to the whole system, avoid running below on untrusted hosts:

curl -k -d 'username=root@pam' --data-urlencode 'password=xxxxxxxxx' https://10.0.0.1:8006/api2/json/access/ticket

Safer variant with the password in a file only readable for the user):

curl -k -d 'username=root@pam' --data-urlencode "password@$HOME/.pve-pass-file" https://10.0.0.1:8006/api2/json/access/ticket

Note that we're using --data-urlencode for the password parameter to ensure neither curl nor the API gets confused about special characters in the password.

Example Response

{ 
  "data": { 
    "CSRFPreventionToken":"4EEC61E2:lwk7od06fa1+DcPUwBTXCcndyAY",  
    "ticket":"PVE:root@pam:4EEC61E2::rsKoApxDTLYPn6H3NNT6iP2mv...", 
    "username":"root@pam"
  }
}

NOTE: Tickets have a limited lifetime of 2 hours. But you can simply get a new ticket by passing the old ticket as password to the /access/ticket method before its lifetime expired.

Example: Use the New Ticket

You need to pass the returned ticket with a cookie to any further request: curl -k -b "PVEAuthCookie=PVE:root@pam:4EEC61E2::rsKoApxDTLYPn6H3NNT6iP2mv..." https://10.0.0.1:8006/api2/json/

Response:

{
  "data": [
    { "subdir": "version" },
    { "subdir": "cluster" },
    { "subdir": "nodes" },
    { "subdir": "storage" },
    { "subdir": "access" },
    { "subdir": "pools" }
  ]
}

Example: Ticket & CSRF for PUT, POST, DELETE

Additionally, any write request (POST, PUT, DELETE) must include the CSRFPreventionToken header:

curl -XDELETE -H "CSRFPreventionToken: 4EEC61E2:lwk7od06fa1+DcPUwBTXCcndyAY" ...

API Tokens

API tokens allow stateless access to most parts of the REST API by another system, software or API client. Tokens can be generated for individual users and can be given separate permissions and expiration dates to limit the scope and duration of the access. Should the API token get compromised it can be revoked without disabling the user itself.

To use an API token, set the HTTP Authorization header to the a value of the form PVEAPIToken=USER@REALM!TOKENID=UUID when making API requests, or refer to your API client documentation.

Example: Use API Token

curl -H "Authorization: PVEAPIToken=root@pam!monitoring=69ab8098-f2aa-455c-add3-e387aef0a47e" https://10.0.0.1:8006/api2/json/

Note: API tokens do not need CSRF values for POST, PUT or DELETE. Tokens are normally not used in a browser context, so the main attack vector of CSRF is not applicable in the first place.

Step by step example of LXC creation using the API

assumptions:

the node where we login is called APINODE
the node on which is the container will be created is called TARGETNODE
the auth cookie will be placed in the file "cookie"
the CSRF token will be placed in the file "csrftoken"

Note: for ease of use we use the jq(1) package which parses and pretty prints json data

export variables

export APINODE=pve4
export TARGETNODE=pve4

Save an authorization cookie on the hard drive

curl --silent --insecure --data "username=root@pam&password=yourpassword" \
 https://$APINODE:8006/api2/json/access/ticket\
| jq --raw-output '.data.ticket' | sed 's/^/PVEAuthCookie=/' > cookie

Save a CSRF token locally

curl --silent --insecure --data "username=root@pam&password=yourpassword" \
 https://$APINODE:8006/api2/json/access/ticket \
| jq --raw-output '.data.CSRFPreventionToken' | sed 's/^/CSRFPreventionToken:/' > csrftoken

Test auth credentials

We display the target node status

curl  --insecure --cookie "$(<cookie)" https://$APINODE:8006/api2/json/nodes/$TARGETNODE/status | jq '.'

creates an lxc container (with the given parameters)

Note: we need to encode the HTTP POST body when passing non alphanumeric parameters

curl --silent --insecure  --cookie "$(<cookie)" --header "$(<csrftoken)" -X POST\
 --data-urlencode net0="name=myct0,bridge=vmbr0" \
 --data-urlencode ostemplate="local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz" \
 --data vmid=601\
 https://$APINODE:8006/api2/json/nodes/$TARGETNODE/lxc

This should return a json structure containing the task id of the creation process which looks like:

{
  "data": "UPID:pve4:00002F9D:000DC5EA:57500527:vzcreate:602:root@pam:"
}

Make sure you use an available vmid when creating a container.

Using 'pvesh' to access the API

As mentioned above, there is a command line tool called 'pvesh' which exposes the whole REST API. This is the Swiss Army knife for developers and system administrators.

some example commands:

pvesh get /version
pvesh get /access/users

or create a new user:

pvesh create /access/users -userid testuser@pve

or delete that user:

pvesh delete /access/users/testuser@pve

or create and then launch a new container:

pvesh create /nodes/{node}/lxc -vmid 100 -hostname test -storage local \
                                  -password supersecret \
                                  -ostemplate local:vztmpl/debian-9.0-standard_9.5-1_amd64.tar.gz \
                                  -memory 512 -swap 512
pvesh create /nodes/{node}/lxc/100/status/start

where {node} is the name of the node on which the container should be created.

The tool automatically proxies call to other cluster members using ssh.

Clients

Official Proxmox Maintained

perl: https://git.proxmox.com/?p=pve-apiclient.git;a=summary

Available in the Proxmox Repositories, via

apt-get install libpve-apiclient-perl

Community Maintained

python: https://pypi.python.org/pypi/proxmoxer (used in the ansible proxmox and proxmox_kvm modules); https://github.com/remofritzsche/proxmox-utils (Console Client); https://github.com/baseblack/Proxmoxia (Wrapper); https://github.com/pcdummy/pmxc (Console Client)

PowerShell: https://github.com/Corsinvest/cv4pve-api-powershell

ruby: https://github.com/nledez/proxmox

nodejs: https://www.npmjs.com/package/proxmox; https://github.com/AmiCole/pvea; https://github.com/Corsinvest/cv4pve-api-javascript

c#: https://github.com/ionelanton/ProxmoxSharp; https://github.com/Corsinvest/cv4pve-api-dotnet; https://github.com/Corsinvest/cv4pve-cli; https://github.com/Corsinvest/cv4pve-botgram; https://github.com/Corsinvest/cv4pve-pepper

PHP: https://github.com/CpuID/pve2-api-php-client; https://github.com/ZzAntares/ProxmoxVE; https://github.com/aheahe/pve-cli-utils; https://github.com/Corsinvest/cv4pve-api-php; https://github.com/MrKampf/proxmoxVE

java: https://github.com/Elbandi/pve2-api-java; https://github.com/Corsinvest/cv4pve-api-java

perl: http://search.cpan.org/~djzort/Net-Proxmox-VE-0.006/

Go: https://github.com/Telmate/proxmox-api-go; https://github.com/Telmate/terraform-provider-proxmox (uses the Go API helper to provide Terraform integration)

Please add any other clients here as they become available.

References

[1] RESTful Web Services - Web services for the real world

By Leonard Richardson and Sam Ruby, Publisher: O'Reilly Media, Released: May 2007

[2] JSON Schema links: http://json-schema.org/

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