NX-API

About NX-API

On Cisco Nexus devices, command-line interfaces (CLIs) are run only on the device. NX-API improves the accessibility of these CLIs by making them available outside of the switch by using HTTP/HTTPS. You can use this extension to the existing Cisco Nexus CLI system on the Cisco Nexus 7000 Series devices. NX-API supports show commands, and configurations.

NX-API supports JSON-RPC, JSON, and XML formats.

Transport

NX-API uses HTTP/HTTPS as its transport. CLIs are encoded into the HTTP/HTTPS POST body.

The NX-API backend uses the Nginx HTTP server.

Message Format

NX-API is an enhancement to the Cisco Nexus 7000 Series CLI system, which supports XML output. NX-API also supports JSON output format for specific commands.


Note

  • NX-API XML output presents information in a user-friendly format.

  • NX-API XML does not map directly to the Cisco NX-OS NETCONF implementation.

  • NX-API XML output can be converted into JSON.

Security

NX-API supports HTTPS. All communication to the device is encrypted when you use HTTPS.

NX-API is integrated into the authentication system on the device. Users must have appropriate accounts to access the device through NX-API. NX-API uses HTTP basic authentication. All requests must contain the username and password in the HTTP header.


Note

You should consider using HTTPS to secure your user's login credentials.

You can enable NX-API by using the feature manager CLI command. NX-API is disabled by default.

NX-API provides a session-based cookie, nxapi_auth when users first successfully authenticate. With the session cookie, the username and password are included in all subsequent NX-API requests that are sent to the device. The username and password are used with the session cookie to bypass performing the full authentication process again. If the session cookie is not included with subsequent requests, another session cookie is required and is provided by the authentication process. Avoiding unnecessary use of the authentication process helps to reduce the workload on the device.


Note

A nxapi_auth cookie expires in 600 seconds (10 minutes). This value is a fixed and cannot be adjusted.


Note
NX-API performs authentication through a programmable authentication module (PAM) on the switch. Use cookies to reduce the number of PAM authentications, which reduces the load on the PAM.

Using NX-API

The commands, command type, and output type for the Cisco Nexus 7000 Series devices are entered using NX-API by encoding the CLIs into the body of a HTTP/HTTPs POST. The response to the request is returned in XML, JSON, or JSON-RPC output format.


Note

For more details about NX-API response codes, see NX-API Response Codes.

You must enable NX-API with the feature manager CLI command on the device. By default, NX-API is disabled.

The following example shows how to configure and launch the NX-API Sandbox:

  • Enable the management interface. 

    switch# conf t
switch(config)# interface mgmt 0
switch(config)# ip address 198.51.100.1/24
switch(config)# vrf context managment
switch(config)# ip route 203.0.113.1/0 1.2.3.1

  • Enable the NX-API nxapi feature. 

    switch# conf t
switch(config)# feature nxapi

The following example shows a request and its response in XML format:

Request: 

<?xml version="1.0"?>
<ins_api>
  <version>1.0</version>
  <type>cli_show</type>
  <chunk>0</chunk>
  <sid>sid</sid>
  <input>show switchname</input>
  <output_format>xml</output_format>
</ins_api>

Response: 

<?xml version="1.0" encoding="UTF-8"?>
<ins_api>
  <type>cli_show</type>
  <version>1.0</version>
  <sid>eoc</sid>
  <outputs>
    <output>
      <body>
      <hostname>switch</hostname>
     </body>
      <input>show switchname</input>
      <msg>Success</msg>
      <code>200</code>
    </output>
  </outputs>
</ins_api>

The following example shows a request and its response in JSON format:

Request: 

{
  "ins_api": {
    "version": "1.0",
    "type": "cli_show",
    "chunk": "0",
    "sid": "1",
    "input": "show switchname",
    "output_format": "json"
  }
}

Response: 

{
  "ins_api": {
    "type": "cli_show",
    "version": "1.0",
    "sid": "eoc",
    "outputs": {
      "output": {
        "input": "show switchname",
        "msg": "Success",
        "code": "200",
        "body": {
          "hostname": "switch"
        }
      }
    }
  }
}

The following example shows a request and response in JSON-RPC format.

Request: 

[
  {
    "jsonrpc": "2.0",
    "method": "cli",
    "params": {
      "cmd": "show switchname",
      "version": 1
    },
    "id": 1
  }
]

Response: 

{
  "jsonrpc": "2.0",
  "result": {
    "body": {
      "hostname": "switch"
    }
  },
  "id": 1
}

Sending Requests

To send NX-API requests via HTTP, use http://<ip-address-of-switch>/ins.

To send NX-API requests with additional security via HTTPS, use https://<ip-address-of-switch>/ins.

The IP Address of the management interface is <ip-address-of-switch>.


Note

The HTTP request must contain the content-type field in the header. For JSON-RPC requests this must be equivalent to application/json-rpc. For the proprietary formats this should be either text/xml or text/json depending on the input format being used.

Obtaining the XSD Files

Procedure

Step 1

From your browser, navigate to the Cisco software download site at the following URL:

http://software.cisco.com/download/navigator.html

The Download Software page opens.

Step 2

In the Select a Product list, choose Switches > Data Center Switches > platform > model .

Step 3

If you are not already logged in as a registered Cisco user, you are prompted to log in now.

Step 4

From the Select a Software Type list, choose NX-OS XML Schema Definition .

Step 5

Find the desired release and click Download.

Step 6

If you are requested, follow the instructions to apply for eligibility to download strong encryption software images.

The Cisco End User License Agreement opens.

Step 7

Click Agree and follow the instructions to download the file to your PC.

NX-API Sandbox

The NX-API Sandbox is the web-based user interface that you use to enter the commands, command type, and output type for the Cisco Nexus 7000 Series device using HTTP/HTTPS. After posting the request, the output response is displayed.

By default, NX-API is disabled. Begin enabling NX-API with the feature manager CLI command on the switch. Then enable NX-API with the nxapi sandbox command.

Use a browser to access the NX-API Sandbox.


Note

When using the NX-API Sandbox, Cisco recommends that you use the Firefox browser, release 24.0 or later.

The following example shows how to configure and launch the NX-API Sandbox:

  • Enable the management interface. 

    switch# conf t
switch(config)# interface mgmt 0
switch(config)# ip address 198.51.100.1/24
switch(config)# vrf context managment
switch(config)# ip route 203.0.113.1/0 1.2.3.1

  • Enable the NX-API nxapi feature. 

    switch# conf t
switch(config)# feature nxapi
switch(config)# nxapi sandbox

  • Open a browser and enter http://mgmt-ip to launch the NX-API Sandbox. The following figure is an example of a request and output response.

In the NX-API Sandbox, you specify the commands, command type, and output type in the top pane. Click the POST Request button above the left pane to post the request. Brief descriptions of the request elements are displayed below the left pane.

After the request is posted, the output response is displayed in the right pane.

You can generate Java or JavaScript for each of the request posted through sandbox. To generate Java or Javascript code for each of the requests, click the Java or JavaScript button in the Request pane.

The following sections describe the commands to manage NX-API and descriptions of the elements of the request and the output response.

NX-API Management Commands

You can enable and manage NX-API with the CLI commands listed in the following table.

Table 1. NX-API Management Commands
NX-API Management Command Description

feature nxapi

Enables NX-API.

no feature nxapi

Disables NX-API.

nxapi {http|https} port port

Specifies a port.

no nxapi {http|https}

Disables HTTP or HTTPS.

show nxapi

Displays port information, NX-API enable or disable status, and sandbox enable or disable status.

nxapi sandbox

Enables NX-API sandbox.

no nxapi sandbox

Disables NX-API sandbox.

nxapi certificate certpath key keypath

Specifies the upload of the following:

  • HTTPS certificate when certpath is specified.

  • HTTPS key when keypath is specified.

NX-API Request Elements

NX-API request elements are sent to the device in XML format, JSON format, or JSON-RPC format. The HTTP header of the request must identify the content type of the request.


Note

A lock will be released by the system if the session that holds the lock is terminated for any reason. The session that acquired the lock can only perform necessary configurations.

When the input request format is XML or JSON, use the NX-API elements that are listed in the following table to specify a CLI command:

Table 2. NX-API Request Elements

NX-API Request Element

Description

version

Specifies the NX-API version.

type

Specifies the type of command to be executed.

The following types of commands are supported:

  • cli_show

    CLI show commands that expect structured output. If the command does not support XML output, an error message is returned.

  • cli_show_ascii

    CLI show commands that expect ASCII output. This aligns with existing scripts that parse ASCII output. Users are able to use existing scripts with minimal changes.

  • cli_conf

    CLI configuration commands.

Note 

  • Each command is only executable with the current user's authority.

  • The pipe operation is supported in the output when the message type is ASCII. If the output is in XML format, the pipe operation is not supported.

  • A maximum of 10 consecutive show commands are supported. If the number of show commands exceeds 10, the 11th and subsequent commands are ignored.

  • No interactive commands are supported.

chunk

Some show commands can return a large amount of output. For the NX-API client to start processing the output before the entire command completes, NX-API supports output chunking for show commands.

Enable or disable chunk with the following settings:

0

Do not chunk output.

1

Chunk output.

Note 

Only show commands support chunking. When a series of show commands are entered, only the first command is chunked and returned.

The output message format is XML. (XML is the default.) Special characters, such as < or >, are converted to form a valid XML message (< is converted into &lt; > is converted into &gt).

You can use XML SAX to parse the chunked output.

Note 

When chunking is enabled, the message format is limited to XML. JSON output format is not supported when chunking is enabled.

sid

The session ID element is valid only when the response message is chunked. To retrieve the next chunk of the message, you must specify a sid to match the sid of the previous response message.

input

Input can be one command or multiple commands. However, commands that belong to different message types should not be mixed. For example, show commands are cli_show message type and are not supported in cli_conf mode.

Note 

Multiple commands are separated with " ; ". (The ; must be surrounded with single blank characters.)

The following are examples of multiple commands:

cli_show 

show version ; show interface brief ; show vlan

cli_conf 

interface Eth4/1 ; no shut ; switchport

output_format

The available output message formats are the following:

xml

Specifies output in XML format.

json

Specifies output in JSON format.

Note 

The Cisco Nexus 7000 Series CLI supports XML output, which means that the JSON output is converted from XML. The conversion is processed on the switch.

To manage the computational overhead, the JSON output is determined by the amount of output. If the output exceeds 1 MB, the output is returned in XML format. When the output is chunked, only XML output is supported.

The content-type header in the HTTP/HTTPS headers indicate the type of response format (XML or JSON).

When JSON-RPC is the input request format, use the NX-API elements that are listed in the following table to specify a CLI command:

Table 3. NX-API Request Elements

NX-API Request Element

Description

jsonrpc

A String specifying the version of the JSON-RPC protocol.

Version must be 2.0.

method

A string containing the name of the method to be invoked.

NX-API supports either:

  • cli show or configuration commands

  • cli_ascii show or configuration commands; output without formatting

params

A structured value that holds the parameter values used during the invocation of the method.

It must contain the following:

  • cmd a CLI command

  • version NX-API request version identifier

id

An optional identifier established by the client that must contain a string, number, or null value, if it is specified. The value should normally not be null and numbers contain no fractional parts. If the user does not specify the id parameter, the server assumes the request is simply a notification resulting in a no response. For example, id : 1

NX-API Response Elements

When the input request is in XML or JSON format, the response contain the following:

Table 4. NX-API Response Elements

NX-API Response Element

Description

version

NX-API version.

type

Type of command to be executed.

sid

Session ID of the response. This element is valid only when the response message is chunked.

outputs

Tag that encloses all command outputs.

When multiple commands are in cli_show or cli_show_ascii, each command output is enclosed by a single output tag.

When the message type is cli_conf, there is a single output tag for all the commands because cli_conf commands require context.

output

Tag that encloses the output of a single command output.

For cli_conf message type, this element contains the outputs of all the commands.

input

Tag that encloses a single command that was specified in the request. This element helps associate a request input element with the appropriate response output element.

body

Body of the command response.

code

Error code returned from the command execution.

NX-API uses standard HTTP error codes as described by the Hypertext Transfer Protocol (HTTP) Status Code Registry (http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml).

msg

Error message associated with the returned error code.

NX-API Response Elements for JSON-RPC Requests

The response object of all JSON-RPC requests will be in JSON-RPC 2.0 response format as defined in the following table.

NX-API Response Element

Description

jsonrpc

A string specifying the version of the JSON-RPC protocol. Will be exactly 2.0.

result

This field is only included on success.

The value of this field contains the requested CLI output.

error

This field is only included on error (mutually exclusive with the result object).

The error object contains the following:

  • code An integer error code as specified by the JSON-RPC specification.

  • message A human readable string to correspond with the error code.

  • data An optional structure that contains useful information (such as CLI error messages or additional information).

id

The same value as the id in the corresponding request object. When there is a problem parsing the id in the request, this value is null.