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 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

PVE uses a Token Based Authentication. All request to the API need to include that token inside a Cookie. We usually call that token a 'ticket'. Additionally, any write 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

# curl -k -d "username=root@pam&password=yourpassword"  https://10.0.0.1:8006/api2/json/access/ticket 
{ "data": { 
  "CSRFPreventionToken":"4EEC61E2:lwk7od06fa1+DcPUwBTXCcndyAY",  
  "ticket":"PVE:root@pam:4EEC61E2::rsKoApxDTLYPn6H3NNT6iP2mv...", 
  "username":"root@pam"}
}

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/

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

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

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

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.