Switch to slf4k and logback to be able to set the log level at runtime

SimpleLogger cannot set the log level at runtime, and kotlin-logging
does not seem to expose a way to access the actual logger implementation
in order to set the log level, see

oshai/kotlin-logging#20 (comment)

Change-Id: I8f769fc4113bff25ac2dc84732862523025edd68

Author: sschuberth

build.gradle

@@ -34,14 +34,8 @@ dependencyUpdates.resolutionStrategy = {
     }
 }
 
-mainClassName = 'Main'
-
 applicationName = 'pran'
-applicationDefaultJvmArgs = [
-        '-Dorg.slf4j.simpleLogger.levelInBrackets=true',
-        '-Dorg.slf4j.simpleLogger.showLogName=false',
-        '-Dorg.slf4j.simpleLogger.showThreadName=false'
-]
+mainClassName = 'Main'
 
 sourceSets {
     funTest {
@@ -52,6 +46,10 @@ sourceSets {
 
 repositories {
     jcenter()
+
+    maven {
+        url 'http://dl.bintray.com/nfrankel/maven'
+    }
 }
 
 dependencies {
@@ -61,10 +59,9 @@ dependencies {
     compile 'com.github.salomonbrys.kotson:kotson:2.5.0'
     compile 'com.vdurmont:semver4j:2.0.2'
 
-    // Use slf4j-simple as logger for kotlin-logging, as the latter is a wrapper for slf4j and depends on an
-    // implementation of slf4j.
-    compile 'io.github.microutils:kotlin-logging:1.4.5'
-    compile 'org.slf4j:slf4j-simple:1.7.25'
+    // Use logback-classic as the logger for slf4k as it allows to change the log level at runtime.
+    compile 'ch.frankel.log4k:slf4k-api:1.0.0'
+    compile 'ch.qos.logback:logback-classic:1.2.3'
 
     funTestCompile sourceSets.main.output
     funTestCompile sourceSets.test.output

src/main/kotlin/Main.kt

@@ -13,14 +13,18 @@ import java.nio.file.attribute.BasicFileAttributes
 
 import kotlin.system.exitProcess
 
-import mu.KotlinLogging
-
-internal val log = KotlinLogging.logger {}
+@Suppress("UnsafeCast")
+internal val log = org.slf4j.LoggerFactory.getLogger({}.javaClass) as ch.qos.logback.classic.Logger
 
 /**
  * The main entry point of the application.
  */
 object Main {
+    init {
+        // Change the default log level from DEBUG to INFO before any other constructors are run.
+        log.level = ch.qos.logback.classic.Level.INFO
+    }
+
     class PackageManagerListConverter : IStringConverter<List<PackageManager>> {
         override fun convert(managers: String): List<PackageManager> {
             // Map lower-cased package manager class names to their instances.
@@ -57,6 +61,10 @@ object Main {
         jc.parse(*args)
         jc.programName = "pran"
 
+        if (debug) {
+            log.level = ch.qos.logback.classic.Level.DEBUG
+        }
+
         if (help) {
             jc.usage()
             exitProcess(1)

src/main/kotlin/Utils.kt

@@ -44,7 +44,7 @@ class ProcessCapture(workingDir: File?, vararg command: String) {
     private val process = builder.start()
 
     init {
-        if (Main.debug) {
+        if (log.isDebugEnabled) {
             log.debug("Keeping temporary files:")
             log.debug(stdoutFile.absolutePath)
             log.debug(stderrFile.absolutePath)

src/main/kotlin/managers/NPM.kt

@@ -1,5 +1,7 @@
 package com.here.provenanceanalyzer.managers
 
+import ch.frankel.slf4k.*
+
 import com.github.salomonbrys.kotson.contains
 import com.github.salomonbrys.kotson.forEach
 import com.github.salomonbrys.kotson.fromJson
@@ -11,7 +13,6 @@ import com.google.gson.Gson
 import com.google.gson.JsonObject
 
 import com.here.provenanceanalyzer.model.Dependency
-import com.here.provenanceanalyzer.Main
 import com.here.provenanceanalyzer.OS
 import com.here.provenanceanalyzer.PackageManager
 import com.here.provenanceanalyzer.ProcessCapture
@@ -98,9 +99,7 @@ object NPM : PackageManager(
      * dependency tree.
      */
     fun installDependencies(workingDir: File, managerCommand: String): Dependency {
-        if (Main.debug) {
-            log.debug("Using '$managerCommand' to install ${javaClass.simpleName} dependencies.")
-        }
+        log.debug { "Using '$managerCommand' to install ${javaClass.simpleName} dependencies." }
 
         // Install all NPM dependencies to enable NPM to list dependencies.
         val install = ProcessCapture(workingDir, managerCommand, "install")
@@ -124,9 +123,7 @@ object NPM : PackageManager(
         val modulesDir = File(workingDir, "node_modules")
 
         // Collect first-order production dependencies and their transitive production dependencies.
-        if (Main.debug) {
-            log.debug("Using '$npm' to list production dependencies.")
-        }
+        log.debug { "Using '$npm' to list production dependencies." }
 
         // Note that listing dependencies fails if peer dependencies are missing.
         @Suppress("UnsafeCast")
@@ -138,9 +135,7 @@ object NPM : PackageManager(
         }
 
         // Collect first-order development dependencies and their transitive production dependencies.
-        if (Main.debug) {
-            log.debug("Using '$npm' to list development dependencies.")
-        }
+        log.debug { "Using '$npm' to list development dependencies." }
 
         // Note that listing dependencies fails if peer dependencies are missing.
         @Suppress("UnsafeCast")