Use system-native linebreaks.

For example, if `false` happened to be the only value on a line, this
would be parsed as valid JSON (a boolean) but it is not a structured log
message that slfmt should try to parse and format.

README.md

@@ -0,0 +1,87 @@
+# Structured Log Formatter
+**Terminal utility to pretty-print JSON-strucutred log lines.**
+
+## Usage
+
+`slfmt` is intended to be used to filter logging output from a process. It
+reads from `stdin` and writes to `stdout`. It expects to see a JSON object on
+each line of input, and will pretty-print the object to `stdout`. Escape codes
+in the log lines (`\n` for newlines, etc.) are supported and will be expanded
+in the output.
+
+Any lines that are not valid JSON objects will be printed as-is to `stdout`.
+
+Example:
+
+```bash
+./run-server | slfmt
+```
+
+Sample Output:
+
+```
+---------------------------------------------------------------------------------------
+scope:     "server/rest_api"
+level:     "ERROR"
+ts:
+  2025-01-03T08:46:35-06:00 (local)  2025-01-03T14:46:35Z (UTC)
+msg:       unhandled exception (DbError)
+err:
+  ERROR:  relation "users" does not exist
+  LINE 1: SELECT id FROM users WHERE id = '43422d65-6874-44ce-b9b3-f8c...
+                         ^
+
+stack:
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(519) workerProc
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(450) runTask
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy/routers.nim(271) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/api.nim(65) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/auth.nim(74) extractSession
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(599) createOrUpdateUser
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(384) createOrUpdateRecord
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(497) getAllRows
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(174) setupQuery
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(116) dbError
+  [[reraised from:
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(519) workerProc
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(450) runTask
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy/routers.nim(271) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/api.nim(65) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/auth.nim(74) extractSession
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(727) createOrUpdateUser
+  ]]
+
+
+
+---------------------------------------------------------------------------------------
+scope:     "server/rest_api"
+level:     "ERROR"
+ts:
+  2025-01-03T08:46:35-06:00 (local)  2025-01-03T14:46:35Z (UTC)
+msg:       unhandled exception (DbError)
+err:
+  ERROR:  relation "users" does not exist
+  LINE 1: SELECT id FROM users WHERE id = '43422d65-6874-44ce-b9b3-f8c...
+                         ^
+
+stack:
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(519) workerProc
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(450) runTask
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy/routers.nim(271) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/api.nim(65) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/auth.nim(74) extractSession
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(599) createOrUpdateUser
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(384) createOrUpdateRecord
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(497) getAllRows
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(174) setupQuery
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/db_connector-0.1.0-d68319e3785fa937f0465ea915e942b61b6b5442/db_connector/db_postgres.nim(116) dbError
+  [[reraised from:
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(519) workerProc
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy.nim(450) runTask
+  /home/username/.local/share/mise/installs/nim/2.2.0/nimble/pkgs2/mummy-0.4.5-cb7f70cd4d6fd3a563e00e664cfbd8cbd3c39b79/mummy/routers.nim(271) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/api.nim(65) :anonymous
+  /home/username/projects/server/api/src/main/nim/server_api/auth.nim(74) extractSession
+  /home/username/projects/fiber-orm-nim/src/fiber_orm.nim(727) createOrUpdateUser
+  ]]
+
+```

slfmt.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.1.0"
+version       = "0.2.4"
 author        = "Jonathan Bernard"
 description   = "Small utility to pretty-print strucutured logs."
 license       = "MIT"
@@ -10,5 +10,5 @@ bin           = @["slfmt"]
 
 # Dependencies
 
-requires "nim >= 2.2.0"
-requires "timeutils"
+requires @["nim >= 2.2.0", "docopt >= 0.7.1"]
+requires @["timeutils", "zero_functional"]

src/slfmt.nim

@@ -1,19 +1,35 @@
-import std/[json, sequtils, streams, strutils, terminal, times]
-import timeutils
-#import docopt
+import std/[json, options, sequtils, streams, strutils, terminal, times]
+import docopt, timeutils, zero_functional
 
-const VERSION = "0.1.0"
+from std/logging import Level
+from std/sequtils import toSeq
 
-# const USAGE = """Usage:
-#   slfmt
-#
-# Options:
-#
-#   -h, --help            Print this usage and help information
+const VERSION = "0.2.4"
+
+const USAGE = """Usage:
+   slfmt [options]
+
+Options:
+
+   -h, --help               Print this usage and help information
+   -c, --compact            Compact output
+   -l, --log-level <lvl>    Only show log events at or above this level
+   -n, --namespace <ns>     Only show log events from this namespace
+"""
 
 const fieldDisplayOrder = @[
   "scope", "level", "ts", "code", "sid", "sub", "msg", "err", "stack", "method", "args"]
 
+func parseLogLevel(s: string): Level =
+  case s.toUpper
+  of "DEBUG": result = Level.lvlDebug
+  of "INFO": result = Level.lvlInfo
+  of "NOTICE": result = Level.lvlNotice
+  of "WARN": result = Level.lvlWarn
+  of "ERROR": result = Level.lvlError
+  of "FATAL": result = Level.lvlFatal
+  else: result = Level.lvlAll
+
 func decorate(
     s: string,
     fg = fgDefault,
@@ -29,7 +45,7 @@ func decorate(
   result &= s & ansiResetCode
 
 
-proc formatField(name: string, value: JsonNode): string =
+proc fullFormatField(name: string, value: JsonNode): string =
   result = decorate(name, fgCyan) & ":" & " ".repeat(max(1, 10 - name.len))
 
   var strVal: string = ""
@@ -42,38 +58,103 @@ proc formatField(name: string, value: JsonNode): string =
     of "err": strVal = decorate(value.getStr, fgRed)
     of "msg": strVal = decorate(value.getStr, fgYellow)
     of "stack": strVal = decorate(value.getStr, fgBlack, {styleBright})
+    else:
+      if value.kind == JString: strVal = decorate(value.getStr)
       else: strVal = pretty(value)
 
   let valLines = splitLines(strVal)
-  if name.len > 10 or strVal.len + 16 > terminalWidth() or valLines.len > 1:
-    result &= "\n" & valLines.mapIt("  " & it).join("\n") & "\n"
-  else: result &= strVal & "\n"
+  if name.len + strVal.len + 6 > terminalWidth() or valLines.len > 1:
+    result &= "\p" & valLines.mapIt("  " & it).join("\p") & "\p"
+  else: result &= strVal & "\p"
 
-proc prettyPrintFormat(logLine: string): string =
-  try:
-    var logJson = parseJson(logLine)
-
-    result = '-'.repeat(terminalWidth())
+proc fullFormat(logJson: JsonNode): string =
+  result = '-'.repeat(terminalWidth()) & "\p"
 
   # Print the known fields in order first
   for f in fieldDisplayOrder:
     if logJson.hasKey(f):
-        result &= formatField(f, logJson[f])
+      result &= fullFormatField(f, logJson[f])
       logJson.delete(f)
 
   # Print the rest of the fields
-    for (key, val) in pairs(logJson): result &= formatField(key, val)
+  for (key, val) in pairs(logJson): result &= fullFormatField(key, val)
 
-    result &= "\n"
+  result &= "\p"
 
-  except ValueError, JsonParsingError:
-    result = logLine
+proc compactFormat(logJson: JsonNode): string =
+  let ts = parseIso8601(logJson["ts"].getStr).local.formatIso8601
+  var level = logJson["level"].getStr
+  if level == "ERROR": level = decorate(alignLeft(level, 7), fgRed)
+  elif level == "WARN": level = decorate(alignLeft(level, 7), fgYellow)
+  else: level = alignLeft(level, 7)
+
+  result = "$1 $2 $3: $4" % [
+    level,
+    decorate(alignLeft(ts[0..21], 23), fgBlue, {styleBright}),
+    decorate(logJson["scope"].getStr, fgGreen),
+    decorate(logJson["msg"].getStr, fgYellow)]
+
+  let restNodes = (toSeq(pairs(logJson))) -->
+    filter(not ["level", "scope", "ts", "msg"].contains(it[0]))
+
+  let restMsg = join(restNodes -->
+    map("$1: $2" % [
+      decorate(it[0], fgCyan),
+      if it[1].kind == JString: it[1].getStr
+      else: pretty(it[1]),
+      "  "]))
+
+  if restMsg.len + result.len + 2 < terminalWidth():
+    result &= "  " & restMsg
+  else:
+    var line = "  "
+    for (key, val) in restNodes:
+      let fieldVal =
+        if val.kind == JString: val.getStr
+        else: pretty(val)
+      let field = "$1: $2" % [decorate(key, fgCyan), fieldVal]
+      if line.len + field.len + 2 > terminalWidth():
+        result &= "\p  " & line
+        line = "  "
+      line &= field & "  "
+    result &= "\p  " & line
+
+proc parseLogLine(logLine: string): JsonNode =
+  result = parseJson(logLine)
 
 when isMainModule:
   try:
+    let args = docopt(USAGE, version = VERSION)
+
+    let logLevel =
+      if args["--log-level"]: some(parseLogLevel($args["--log-level"]))
+      else: none[Level]()
+
+    let namespace =
+      if args["--namespace"]: some($args["--namespace"])
+      else: none[string]()
+
+    let compact = args["--compact"]
+
     var line: string = ""
     let sin = newFileStream(stdin)
-    while(sin.readLine(line)): stdout.writeLine(prettyPrintFormat(line))
+    while(sin.readLine(line)):
+      try:
+        let logJson = parseLogLine(line)
+        if logJson.kind != JObject:
+          raise newException(JsonParsingError, "Expected a JSON object")
+
+        if logLevel.isSome and logJson.hasKey("level"):
+          let lvl = parseLogLevel(logJson["level"].getStr)
+          if lvl < logLevel.get: continue
+
+        if namespace.isSome and logJson.hasKey("scope"):
+          if not logJson["scope"].getStr.startsWith(namespace.get): continue
+
+        if compact: stdout.writeLine(compactFormat(logJson))
+        else: stdout.writeLine(fullFormat(logJson))
+      except ValueError, JsonParsingError:
+        stdout.writeLine(line)
   except:
     stderr.writeLine("slfmt - FATAL: " & getCurrentExceptionMsg())
     stderr.writeLine(getCurrentException().getStackTrace())