Always write to log on startup failure (#1550)

microsoft · Mar 12, 2021 · 93657fd · 93657fd
1 parent c85fa18
commit 93657fd
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Showing 3 changed files with 35 additions and 4 deletions.
diff --git a/...in/java/com/microsoft/applicationinsights/agent/internal/wasbootstrap/MainEntryPoint.java b/...in/java/com/microsoft/applicationinsights/agent/internal/wasbootstrap/MainEntryPoint.java
@@ -21,8 +21,12 @@
 package com.microsoft.applicationinsights.agent.internal.wasbootstrap;
 
 import java.io.File;
+import java.io.FileOutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
 import java.lang.instrument.Instrumentation;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.util.Locale;
 
@@ -134,19 +138,34 @@ private static void logErrorMessage(Logger startupLogger, String message, boolea
             try {
                 // IF the startupLogger failed to be initialized due to configuration syntax error, try initializing it here
                 Path agentPath = new File(bootstrapURL.toURI()).toPath();
-                startupLogger = configureLogging(new SelfDiagnostics(), agentPath);
+                SelfDiagnostics selfDiagnostics = new SelfDiagnostics();
+                selfDiagnostics.file.path = ConfigurationBuilder.overlayWithEnvVar(
+                        ConfigurationBuilder.APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH, selfDiagnostics.file.path);
+                startupLogger = configureLogging(selfDiagnostics, agentPath);
                 if (isFriendlyException) {
                     startupLogger.error(message);
                 } else {
                     startupLogger.error(message, t);
                 }
-            } catch (Throwable e) {
-                // If the startupLogger still have some issues being initialized, just print the error stack trace
+            } catch (Throwable ignored) {
+                // this is a last resort in cases where the JVM doesn't have write permission to the directory where the agent lives
+                // and the user has not specified APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH
+
+                // If the startupLogger still have some issues being initialized, print the error stack trace to stderr
                 if (isFriendlyException) {
                     System.err.println(message);
                 } else {
                     t.printStackTrace();
                 }
+                // and write to a temp file because some environments do not have (easy) access to stderr
+                String tmpDir = System.getProperty("java.io.tmpdir");
+                File file = new File(tmpDir, "applicationinsights.log");
+                try {
+                    Writer out = new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8);
+                    out.write(message);
+                    out.close();
+                } catch (Throwable ignored2) {
+                }
             }
         }
     }

diff --git a/...t/applicationinsights/agent/internal/wasbootstrap/configuration/ConfigurationBuilder.java b/...t/applicationinsights/agent/internal/wasbootstrap/configuration/ConfigurationBuilder.java
@@ -64,6 +64,7 @@ public class ConfigurationBuilder {
     private static final String APPLICATIONINSIGHTS_INSTRUMENTATION_LOGGING_LEVEL = "APPLICATIONINSIGHTS_INSTRUMENTATION_LOGGING_LEVEL";
 
     private static final String APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_LEVEL = "APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_LEVEL";
+    public static final String APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH = "APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH";
 
     private static final String APPLICATIONINSIGHTS_PREVIEW_OTEL_API_SUPPORT = "APPLICATIONINSIGHTS_PREVIEW_OTEL_API_SUPPORT";
 
@@ -218,6 +219,7 @@ public static void overlayEnvVars(Configuration config) throws IOException {
         config.sampling.percentage = overlayWithEnvVar(APPLICATIONINSIGHTS_SAMPLING_PERCENTAGE, config.sampling.percentage);
 
         config.selfDiagnostics.level = overlayWithEnvVar(APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_LEVEL, config.selfDiagnostics.level);
+        config.selfDiagnostics.file.path = overlayWithEnvVar(APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH, config.selfDiagnostics.file.path);
 
         config.preview.openTelemetryApiSupport = overlayWithEnvVar(APPLICATIONINSIGHTS_PREVIEW_OTEL_API_SUPPORT, config.preview.openTelemetryApiSupport);
 
@@ -250,7 +252,7 @@ private static String getWebsiteSiteNameEnvVar() {
         return value;
     }
 
-    static String overlayWithEnvVar(String name, String defaultValue) {
+    public static String overlayWithEnvVar(String name, String defaultValue) {
         String value = getEnvVar(name);
         return value != null ? value : defaultValue;
     }

diff --git a/...soft/applicationinsights/agent/internal/wasbootstrap/configuration/ConfigurationTest.java b/...soft/applicationinsights/agent/internal/wasbootstrap/configuration/ConfigurationTest.java
@@ -337,6 +337,16 @@ public void shouldOverrideSelfDiagnosticsLevel() throws IOException {
         assertEquals("DEBUG", configuration.selfDiagnostics.level);
     }
 
+    @Test
+    public void shouldOverrideSelfDiagnosticsFilePath() throws IOException {
+        envVars.set("APPLICATIONINSIGHTS_SELF_DIAGNOSTICS_FILE_PATH", "/tmp/ai.log");
+
+        Configuration configuration = loadConfiguration();
+        ConfigurationBuilder.overlayEnvVars(configuration);
+
+        assertEquals("/tmp/ai.log", configuration.selfDiagnostics.file.path);
+    }
+
     @Test
     public void shouldOverridePreviewOtelApiSupport() throws IOException {
         envVars.set("APPLICATIONINSIGHTS_PREVIEW_OTEL_API_SUPPORT", "true");