Function to render Graphviz graphs from dot files that are posted in

function.json

{
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    }
  ],
  "disabled": false
}

index.js

//post{ "dot": "digraph { x -> y -> z; }"}

var viz = require('viz.js');
var fs = require('fs');

var svg2png = require("svg2png");

module.exports = function (context, req) {
    context.log('JavaScript HTTP trigger function processed a request.');    

    if (req.body && req.body.dot) {
        
        var dot = req.body.dot;       

        var svg = viz(dot, { format: "svg" });

        svg = svg.replace(/Times,serif/gi, "sans-serif");        

        svg2png(svg, { width: 2560, height: 2048 })
        .then(buffer => {
            context.res = {
                // status: 200, /* Defaults to 200 */
                body: buffer,
                headers: {
                     'Content-Type': 'image/png'
                }               
            };
            context.done();
        });        
    }
    else {
        context.res = {
            status: 400,
            body: "Please pass a dot field in the request body that contains "
        };
        context.done();
    }
    
};

Largersamplepost.json

//thanks http://brandewinder.com/2017/04/01/azure-function-app-diagram/
{
    "dot": "digraph app {\r\nnode [shape=doublecircle,style=filled,color=orange]\r\n    \"check-mentions\"\r\n    \"follow-users\"\r\n    \"process-mention\"\r\n    \"send-tweet\"\r\nnode [shape=box,style=filled,color=yellow]\r\n    \"Timer\"\r\n    \"Blob incontainer\/lastid\"\r\n    \"Queue mentions\"\r\n    \"Queue friends\"\r\n    \"Queue tweets\"\r\nnode [shape=box,style=filled,color=lightblue]\r\n    \"linqtotwitter (4.1.0)\"\r\n    \"Newtonsoft.Json (9.0.1)\"\r\n    \"FSharp.Compiler.Service (9.0.1)\"    \r\nedge [ style=bold ]\r\n    \"Timer\" -> \"check-mentions\" [ label = \"timer\" ]\r\n    \"Queue friends\" -> \"follow-users\" [ label = \"userName\" ]\r\n    \"Queue mentions\" -> \"process-mention\" [ label = \"input\" ]\r\n    \"Queue tweets\" -> \"send-tweet\" [ label = \"input\" ]\r\nedge [ style=solid ]\r\n    \"Blob incontainer\/lastid\" -> \"check-mentions\" [ label = \"previousID\" ]\r\nedge [ style=solid ]\r\n    \"check-mentions\" -> \"Blob incontainer\/lastid\" [ label = \"updatedID\" ]\r\n    \"check-mentions\" -> \"Queue mentions\" [ label = \"mentionsQueue\" ]\r\n    \"check-mentions\" -> \"Queue friends\" [ label = \"friendsQueue\" ]\r\n    \"process-mention\" -> \"Queue tweets\" [ label = \"responseQueue\" ]    \r\nedge [ arrowhead=none,style=dotted,dir=none ]\r\n    \"linqtotwitter (4.1.0)\" -> \"check-mentions\"\r\n    \"Newtonsoft.Json (9.0.1)\" -> \"check-mentions\"\r\n    \"linqtotwitter (4.1.0)\" -> \"follow-users\"\r\n    \"FSharp.Compiler.Service (9.0.1)\" -> \"process-mention\"\r\n    \"Newtonsoft.Json (9.0.1)\" -> \"process-mention\"\r\n    \"linqtotwitter (4.1.0)\" -> \"send-tweet\"\r\n    \"Newtonsoft.Json (9.0.1)\" -> \"send-tweet\"    \r\n}"
}

package.json

{
  "dependencies": {
    "viz.js": "~1.7.1",
    "svg2png": "~4.1.1"
  }
}