Zuko

This is a Clojure/ClojureScript library that works with other Threatgrid data applications.

The initial applications using this library are Naga and Asami.

This library provides functionality for:

• Managing data (especially JSON data) in a graph database. Asami describes this in the wiki entry for Entity Structures.
• Projecting data into tuples suitable for query results or insertion into a graph database. Generation of this data with Zuko is discussed in Asami.
• Logging in Clojure or ClojureScript
• General utilities to avoid duplicating code between projects.

Usage

Include a dependency to this library.

In Leiningen:

[org.clojars.quoll/zuko "0.5.1"]

In deps.edn:

{
  :deps {
    org.clojars.quoll/zuko {:mvn/version "0.5.1"}
  }
}

Logging

The main general purpose code here is the simple logging facility.

Clojure

By default in Clojure, logging function are disabled, which means that using log functions will not create any code. This ensures that a code path is unaffacted when logging is turned off. The easiest way to ensure that logging is enabled is to set logging.enabled in the System Properties:

$ clj -J-Dlogging.enabled=true

Alternatively, it can be set programatically if you're loading the logging namespace dynamically. This may be important to load a namespace that uses logging that you don't want to modify:

(System/setProperty "logging.enabled" "true")
(require '[zuko.logging :as log])

If you want to ensure logging occurs in your own code, then just enable it:

(require '[zuko.logging :as log])
(log/set-enabled! true)

The "enabled" flag is global across all namespaces.

ClojureScript

By default, ClojureScript logging is enabled. This reflects the fact that ClojureScript is typically built and deployed, so it is not usually possible to update a flag to modify actual inlined code.

If you want to ensure that logging is excluded from the final output, then ensure that your ClojureScript code is compiled with -Dlogging.enabled=false

Usage

Logging always checks the current logging level before emitting a log. This can be done dynamically with a number or using the set-logging-level! function, which can take a number or a keyword.

(ns my.program (:require [zuko.logging :as log]))

(log/set-logging-level! :warn)
(log/error "Something went wrong!")
(log/info "This does nothing")
;; temporarily allow through INFO messages
(binding [log/*level* 4]
  (log/info "The level was set to:" log/*level*))

This will output:

my.program WARN: Something went wrong!
my.program INFO: The level was set to:4

Numerical levels

The logging levels are: | Keyword | # | |----------|---| | :fatal | 1 | | :error | 2 | | :warn | 3 | | :info | 4 | | :debug | 5 | | :trace | 6 |

Logging will record any messages that are at the current level or lower. So when level 4 is set (info), then all info, warn, error and fatal messages are recorded.

Bindings must be done by numerical constant, but using set-logging-level! can use a number or the above keywords.

Output

If no output has been set, then all logging will go to stdout by default (or the console in a web browser).

Output can be set dynamically, or by using the set-output! function. Available options are:

• nil or "": write to standard output or console.
• "filename": appends to a file. This works in Clojure or ClojureScript on Node.js.
• Atom: data will be added via conj
• java.io.Writer: sent to the writer (Clojure only).

(def output (atom []))
(log/set-output! output)
(log/debug "step 1")
(binding [log/*output* nil]
  (log/debug "step 2"))
(log/debug "step 3")
(deref output)

This will return:

["my.program DEBUG: step 1" "my.program DEBUG: step 3"]

and standard out will show:

my.program DEBUG: step 2

License

Copyright © 2020-2021 Cisco Systems

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.