purescript-systemd-journald

Tiny wrapper around node-systemd-journald

Installation

In order to successfully install node bindings you have to install systemd library on the system level (on NixOS you need these two: pkgs.pkgconfig, pkgs.systemd). Then you can perform:

bower install purescript-systemd-journald

npm install systemd-journald@^1.3.0

API

Current API is probably too liberal - it will accept any record value as your custom fields definition. You have to be careful because journald ignores fields which starts with underscore so I should probably add class which would prevent this kind of field names.

Usage

As stated above current API doesn't prevent you from passing any record to the logger, but be prepared that this can lead to unexpected results. I think that the best approach is to use just flat records with string values.

When you start inspecting journald messages json structure:

$ journalctl -f -o json-pretty

and run example from tests/Main.purs:

 import Node.Systemd.Journald (journald, debug, alert)

 data Custom = Empty | NonEmpty Int

 main :: Effect Unit
 main = do
   logger ← journald { syslog_identifier: "purescript-systemd-journald-tests"  }
   let
     fields =
       { _ignored: "top"
       , something:
         { how: "how"
         , would: 888
         , journald: \x → "some unicode: λ"
         , store: "store"
         , these: NonEmpty 8
         , values: Empty
         , _nonignored: "nested"
         }
       }
   debug logger "Test message" fields

you would get output like this (truncated):

  {
      "__REALTIME_TIMESTAMP" : "1511883107925132",
      "__MONOTONIC_TIMESTAMP" : "24981575524",
      "_BOOT_ID" : "be9d1e65ca284c8cba3b6d9c64c088c3",
      "_TRANSPORT" : "journal",
      "_UID" : "1000",
      "_GID" : "100",

      ...

      "PRIORITY" : "7",

      ...

      "MESSAGE" : "Test message",
      "SOMETHING_HOW" : "how",
      "SOMETHING_WOULD" : "888",
      "SOMETHING_JOURNALD" : "function (x) {\n                return \"some unicode: \\u03bb\";\n            }",
      "SOMETHING_STORE" : "store",
      "SOMETHING_THESE_VALUE0" : "8",
      "SOMETHING__NONIGNORED" : "nested",

      "_PID" : "32210",
      "_CMDLINE" : "node /run/user/1000/pulp-test1171028-32124-r8jvgk.v8ogrxusor.js",
  }

As you can see nested records are flattened and not all custom fields are present in the log - there is no related field for value: Empty. I'm not sure what is exact pattern of this behavior so if you find any additional interesting examples please let me know.

Native APIs

Native journald API is described here:

http://0pointer.net/blog/projects/journal-submit.html

Bindings API is described here:

https://github.com/jue89/node-systemd-journald