django-collectd-rest is a simple Django application to demonstrate RRD plots generated by collectd or any other rrd data. The application is built on top of django-rest-framework and provides REST API to access the plots.
There are two major things in django-collectd-rest, graphs are grouped into groups. Both the graphs and the groups are accessible through REST API. Using mutable access (POST, PUT, DELETE), you can configure you hierarchy, create new graphs or alter existing ones. You also can grab meta-info or ready PNG images by means of GET requests. Genuine rrdtool is currently used to render the plots.
Newly introduced granularity object is a kind of policy hinting image freshness lifetime, or its time resolution. Currently, it is used to correctly set max-age in response Cache-Control header. The default granularity has max-age=0.
The following prerequisites are required to operate django-collectd-rest:
- django-rest-framework - powerful and flexible toolkit that makes it easy to build Web APIs.
- rrd - high performance data logging and graphing system for time series data.
To use django-collectd-rest in your django project, include the following code into your settings.py:
INSTALLED_APPS = (
#...
'rest_framework',
'collectd_rest',
)Into your urls.py you have to add the following:
urlpatterns = patterns('',
#...
url(r'^collectd_rest/', include('collectd_rest.urls')),
)The whole configuration is stored into the project database, there is not separate dedicated configfile. New graphs and groups are added by creating new objects. The latter can be done in different ways.
Using django database console:
from collectd_rest import models
group = models.GraphGroup(title="The Group", name="group1")
group.save()
graph = models.Graph(title="The Graph", name="graph1", priority=0, command="DEF:cpuuser=/path/to/rrd/cpu-0/cpu-idle.rrd:value:AVERAGE LINE2:cpuuser#000000:legend", group=group)
graph.save()The GraphGroup model has two parameters: human-readable title and lookup field name to access the group by url like http://example.com/collectd_rest/group/{name}/.
The Graph model has way more fields, including priority to sort the graphs inside one group, mandatory parent group, and command to generate rrd plot.
The other ways to configure the application are Django fixtures, Django admin interface, django-rest-framework web browsable interface, and REST API itself. You can also modify the graphs hierarchy dynamically by means of custom REST client.
You may utilise all possible options provided by django-rest-framework. See Tutorial for reference.
You may utilise all caching mechanisms provided by Django framework. See Django's cache framework.
To demonstrate how the framework can be used, let's look at the following JavaScript code (jQuery is used here). The following code renders the group names mygroup into corresponding div element, and the myothergroup into the other one.
<html>
<head>
<script type="text/javascript" src="http://yastatic.net/jquery/2.1.1/jquery.js"></script>
<script>
function renderGraph(graph) {
var name = graph['name'];
var title = graph['title'];
var url = graph['url'];
var code = "<div id=\"" + name + "\" class=\"django-collectd-rest-graph\">\n";
code += "<div>" + title + "</div>\n";
code += "<img src=" + url + " />\n";
code += "</div>\n";
return code;
};
function renderGroup(group) {
var name = group['name'];
var title = group['title'];
var graphs= group['graphs'];
var code = "<div>" + title + "</div><ul>\n";
graphs.forEach(function(g){
code += "<li>" + renderGraph(g) + "</li>\n";
});
code += "</ul>\n";
return code;
}
$(document).ready(function(){
$.get( "http://example.com/collectd_rest/groups/", function( data ) {
data.forEach(function(entry) {
var name = entry['name'];
var code = renderGroup(entry);
$(".django-collectd-rest-group#" + name).html(code);
});
});
});
</script>
</head>
<body>
<div id="test">
</div>
<div class="django-collectd-rest-group" id="mygroup"></div>
<div class="django-collectd-rest-group" id="myothergroup"></div>
</body>
</html>If you have any questions, issues, or pull-requests, you are welcome to use GitHub infrastructure for them.
Copyright (c) 2014, Matwey V. Kornilov
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