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Collection 4

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Florian Forster edited this page Nov 26, 2023 · 1 revision

Collection 4 (abbreviated as c4) is a web-based front-end to data collected by collectd. It is written as a FastCGI application in C.

The two main goals of c4 are performance and versatility: The application has been implemented in a way that handles installations with more than 85,000 files in an efficient manner. The data and appearance of each graph can be configured in a config file in a very flexible manner. Not all output options support this configuration yet, though.

Features

Roadmap / Wishlist

  • Sending a FLUSH command to the daemon using libcollectdclient is mandatory.
  • Currently the code base is cluttered with functions trying to figure out the arguments required for rrdtool graph (rrdgraph(1)). These functions will be moved to a separate place or removed entirely. RRDtool doesn't allow to separate the fetch and create graph phases and therefore doesn't fit the design of c4.
  • Much work has been spent on internal design and optimizations. The HTML printed by the program is very crude and basically a proof of concept. While this will hopefully improve over time, the goal is to make it possible to create nice front-ends on top of c4 using the data is exports as JSON.
  • Make it possible for an ident to match multiple value-lists. One way to do this is to use regular expressions in the selectors of the graph and the def.
  • Make it possible to specify a "fallback" def – a def which is used when no other def matches a given file / data-source.
  • …

Actions

You can think of actions a little applications sitting on top of a library that makes up c4. They provide functionality that is available using this interface. Currently, the following actions are available:

  • graph Prints a graph instance as a PNG image using the librrd. This action will possibly be removed or changed.
  • graph_def_json Exports a graph definition as JSON.
  • instance_data_json Exports the data required to draw a graph instance as JSON.
  • list_graphs Prints a list of graphs as an HTML page. You can optionally request dynamic graphs to be included, too.
  • list_hosts Prints a list of hosts as an HTML page.
  • search Provides a search interface to the graphs provided by c4 using HTML.
  • search_json Provides search facilities and returns data encoded as JSON, so it can be used from JavaScript.
  • show_graph Prints an HTML page listing all the graph instances belonging to a graph.
  • show_graph_json Returns a list of graph instances belonging to a graph as JSON.
  • show_instance Prints an HTML page containing one graph instance, i.e. an actual image. By default the graph image is rendered using JavaScript, but an RRDtool-generated graph can be requested, too, which uses the graph action.
  • usage Prints a list of available actions.

Requirements

See also

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