Add Observability Sample

Closes gh-313

servlet/spring-boot/java/observability/.vscode/settings.json

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+{
+	"java.configuration.updateBuildConfiguration": "interactive"
+}

servlet/spring-boot/java/observability/README.adoc

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+= Spring Observability Sample
+
+This sample demonstrates https://docs.spring.io/spring-security/reference/servlet/integrations/observability.html#page-title[Spring Security's integration with Micrometer].
+
+== Prerequisites
+
+The sample is configured to export traces to Zipkin.
+In order to see these traces, you will need https://github.com/jonatan-ivanov/local-services/tree/main/zipkin[a Zipkin instance] running on `localhost`.
+
+== Using the Sample
+
+After running this sample like so:
+
+.Java
+[source,java,role="primary"]
+----
+./gradlew :bootRun
+----
+
+Then you can query `GET /message` using `user/password` and `admin/password`.
+Using HTTPie, that would look something like this to get a successful response:
+
+```bash
+http -a user:password :8080/message`
+```
+
+If you want to see a failed authentication, try `http -a user:wrong :8080/message`.
+
+If you want to see a failed authorization, try `http -a user:password :8080/secret`

servlet/spring-boot/java/observability/build.gradle

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+plugins {
+	alias(libs.plugins.org.springframework.boot)
+	alias(libs.plugins.io.spring.dependency.management)
+	id "nebula.integtest" version "8.2.0"
+	id 'java'
+}
+
+repositories {
+	mavenCentral()
+	maven { url "https://repo.spring.io/milestone" }
+	maven { url "https://repo.spring.io/snapshot" }
+}
+
+
+dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-actuator'
+	implementation 'org.springframework.boot:spring-boot-starter-security'
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'io.micrometer:micrometer-tracing-bridge-brave'
+	implementation 'io.zipkin.reporter2:zipkin-reporter-brave'
+
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+	testImplementation 'org.springframework.security:spring-security-test'
+}
+
+tasks.withType(Test).configureEach {
+	useJUnitPlatform()
+	
+}

servlet/spring-boot/java/observability/gradle.properties

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+version=6.1.1
+spring-security.version=6.4.0-SNAPSHOT
+org.gradle.jvmargs=-Xmx6g -XX:+HeapDumpOnOutOfMemoryError
+org.gradle.caching=true

servlet/spring-boot/java/observability/gradle/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https://services.gradle.org/distributions/gradle-7.5.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

servlet/spring-boot/java/observability/gradle/libs.versions.toml

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+../../../../../gradle/libs.versions.toml

servlet/spring-boot/java/observability/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.3-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

servlet/spring-boot/java/observability/gradlew

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+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

servlet/spring-boot/java/observability/gradlew.bat

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+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

servlet/spring-boot/java/observability/settings.gradle

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+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+        maven { url 'https://repo.spring.io/milestone' }
+        maven { url "https://repo.spring.io/snapshot" }
+    }
+}

servlet/spring-boot/java/observability/src/integTest/java/example/HelloMethodApplicationITests.java

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+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.util.List;
+
+import io.micrometer.observation.Observation.Context;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.client.observation.ClientRequestObservationContext;
+import org.springframework.http.server.observation.ServerRequestObservationContext;
+import org.springframework.security.authentication.AuthenticationObservationContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests.
+ *
+ * @author Rob Winch
+ * @since 5.0
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class HelloMethodApplicationITests {
+
+	@Autowired
+	TestRestTemplate rest;
+
+	@Autowired
+	ObservationCollector collector;
+
+	// --- /message ---
+
+	@Test
+	void messageWhenNotAuthenticated() {
+		// @formatter:off
+		assertThat(this.rest.getForEntity("/message", String.class).getStatusCode()).isEqualTo(HttpStatus.UNAUTHORIZED);
+		List<Context> starts = this.collector.getStarts();
+		assertThat(starts).extracting((context) -> context.getClass())
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) ClientRequestObservationContext.class)
+				.contains((Class) ServerRequestObservationContext.class);
+	}
+
+	@Test
+	void messageWhenUserThenOk() {
+		ResponseEntity<?> response = this.rest.exchange("/message", HttpMethod.GET, userCredentials(), String.class);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(response.getBody().toString()).isEqualTo("Hello User!");
+		List<Context> starts = this.collector.getStarts();
+		assertThat(starts).extracting((context) -> context.getClass())
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) ClientRequestObservationContext.class)
+				.contains((Class) ServerRequestObservationContext.class);
+	}
+
+	// --- /secret ---
+
+	@Test
+	void secretWhenNotAuthenticated() {
+		assertThat(this.rest.getForEntity("/secret", String.class).getStatusCode()).isEqualTo(HttpStatus.UNAUTHORIZED);
+		List<Context> starts = this.collector.getStarts();
+		assertThat(starts).extracting((context) -> context.getClass())
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) ClientRequestObservationContext.class)
+				.contains((Class) ServerRequestObservationContext.class);
+	}
+
+	@Test
+	void secretWhenUserThenForbidden() {
+		assertThat(this.rest.exchange("/secret", HttpMethod.GET, userCredentials(), String.class).getStatusCode()).isEqualTo(HttpStatus.FORBIDDEN);
+		List<Context> starts = this.collector.getStarts();
+		assertThat(starts).extracting((context) -> context.getClass())
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) ClientRequestObservationContext.class)
+				.contains((Class) ServerRequestObservationContext.class);
+	}
+
+	@Test
+	void secretWhenAdminThenOk() {
+		ResponseEntity<?> response = this.rest.exchange("/secret", HttpMethod.GET, adminCredentials(), String.class);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(response.getBody().toString()).isEqualTo("Hello Admin!");
+		List<Context> starts = this.collector.getStarts();
+		assertThat(starts).extracting((context) -> context.getClass())
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) AuthenticationObservationContext.class)
+				.contains((Class) ClientRequestObservationContext.class)
+				.contains((Class) ServerRequestObservationContext.class);
+	}
+
+	private HttpEntity<?> userCredentials() {
+		HttpHeaders headers = new HttpHeaders();
+		headers.setBasicAuth("user", "password");
+		return new HttpEntity<>(headers);
+	}
+
+	private HttpEntity<?> adminCredentials() {
+		HttpHeaders headers = new HttpHeaders();
+		headers.setBasicAuth("admin", "password");
+		return new HttpEntity<>(headers);
+	}
+
+}

servlet/spring-boot/java/observability/src/integTest/java/resources/application.properties

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+management.tracing.sampling.probability=1.0

servlet/spring-boot/java/observability/src/main/java/example/HelloMethodApplication.java

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+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Simple application that uses method security.
+ *
+ * @author Rob Winch
+ * @since 5.0
+ */
+@SpringBootApplication
+public class HelloMethodApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(HelloMethodApplication.class, args);
+	}
+
+}

servlet/spring-boot/java/observability/src/main/java/example/MessageController.java

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+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Controller for the messages.
+ *
+ * @author Rob Winch
+ * @since 5.0
+ */
+@RestController
+public class MessageController {
+
+	private final MessageService messages;
+
+	public MessageController(MessageService messages) {
+		this.messages = messages;
+	}
+
+	@GetMapping("/message")
+	public String message() {
+		return this.messages.findMessage();
+	}
+
+	@GetMapping("/secret")
+	public String secretMessage() {
+		return this.messages.findSecretMessage();
+	}
+
+}

servlet/spring-boot/java/observability/src/main/java/example/MessageService.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.stereotype.Component;
+
+/**
+ * Message service that has method security on it.
+ *
+ * @author Rob Winch
+ * @since 5.0
+ */
+@Component
+public class MessageService {
+
+	/**
+	 * Gets a message if authenticated.
+	 * @return the message
+	 */
+	@PreAuthorize("isAuthenticated()")
+	public String findMessage() {
+		return "Hello User!";
+	}
+
+	/**
+	 * Gets a message if admin.
+	 * @return the message
+	 */
+	@PreAuthorize("hasRole('ADMIN')")
+	public String findSecretMessage() {
+		return "Hello Admin!";
+	}
+
+}

servlet/spring-boot/java/observability/src/main/java/example/ObservationCollector.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import io.micrometer.observation.Observation.Context;
+import io.micrometer.observation.ObservationHandler;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class ObservationCollector implements ObservationHandler {
+
+	private List<Context> starts = new ArrayList<>();
+
+	@Override
+	public boolean supportsContext(Context context) {
+		return true;
+	}
+
+	@Override
+	public void onStart(Context context) {
+		this.starts.add(context);
+	}
+
+	public List<Context> getStarts() {
+		return this.starts;
+	}
+
+}

servlet/spring-boot/java/observability/src/main/java/example/SecurityConfiguration.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.core.userdetails.User;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.core.userdetails.UserDetailsService;
+import org.springframework.security.provisioning.InMemoryUserDetailsManager;
+import org.springframework.security.web.SecurityFilterChain;
+
+import static org.springframework.security.config.Customizer.withDefaults;
+
+/**
+ * Minimal method security configuration.
+ *
+ * @author Rob Winch
+ * @since 5.0
+ */
+@Configuration
+@EnableMethodSecurity
+public class SecurityConfiguration {
+
+	@Bean
+	SecurityFilterChain springFilterChain(HttpSecurity http) throws Exception {
+		// @formatter:off
+		http
+			// Demonstrate that method security works
+			// Best practice to use both for defense in depth
+			.authorizeHttpRequests((authorize) -> authorize
+				.anyRequest().permitAll()
+			)
+			.httpBasic(withDefaults());
+		// @formatter:on
+		return http.build();
+	}
+
+	@Bean
+	UserDetailsService userDetailsService() {
+		// @formatter:off
+		UserDetails user = User.withDefaultPasswordEncoder()
+			.username("user")
+			.password("password")
+			.roles("USER")
+			.build();
+		UserDetails admin = User.withDefaultPasswordEncoder()
+			.username("admin")
+			.password("password")
+			.roles("ADMIN", "USER")
+			.build();
+		// @formatter:on
+		return new InMemoryUserDetailsManager(user, admin);
+	}
+
+}

servlet/spring-boot/java/observability/src/test/java/example/HelloMethodApplicationTests.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.security.test.context.support.WithAnonymousUser;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * @author Josh Cummings
+ */
+@SpringBootTest
+@AutoConfigureMockMvc
+public class HelloMethodApplicationTests {
+
+	@Autowired
+	MockMvc mvc;
+
+	// --- /message ---
+
+	@Test
+	@WithAnonymousUser
+	void messageWhenNotAuthenticatedThenUnAuthorized() throws Exception {
+		this.mvc.perform(get("/message")).andExpect(status().isUnauthorized());
+	}
+
+	@Test
+	@WithMockUser
+	void messageWhenAuthenticatedThenOk() throws Exception {
+		this.mvc.perform(get("/message")).andExpect(status().isOk());
+	}
+
+	// --- /secret ---
+
+	@Test
+	void secretWhenNotAuthenticatedThenUnAuthorized() throws Exception {
+		this.mvc.perform(get("/secret")).andExpect(status().isUnauthorized());
+	}
+
+	@Test
+	@WithMockUser
+	void secretWhenNotAuthorizedThenForbidden() throws Exception {
+		this.mvc.perform(get("/secret")).andExpect(status().isForbidden());
+	}
+
+	@Test
+	@WithMockUser(roles = "ADMIN")
+	void secretWhenAuthorizedThenOk() throws Exception {
+		this.mvc.perform(get("/secret")).andExpect(status().isOk());
+	}
+
+}

servlet/spring-boot/java/observability/src/test/java/example/MessageServiceTests.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package example;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.security.access.AccessDeniedException;
+import org.springframework.security.authentication.TestingAuthenticationToken;
+import org.springframework.security.core.context.SecurityContext;
+import org.springframework.security.core.context.SecurityContextImpl;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.security.test.context.support.WithSecurityContext;
+import org.springframework.security.test.context.support.WithSecurityContextFactory;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+/**
+ * @author Josh Cummings
+ */
+@SpringBootTest
+public class MessageServiceTests {
+
+	@Autowired
+	MessageService messages;
+
+	// -- findMessage ---
+
+	@Test
+	@WithUnauthenticatedUser
+	void findMessageWhenNotAuthenticatedThenDenied() {
+		assertThatExceptionOfType(AccessDeniedException.class).isThrownBy(this.messages::findMessage);
+	}
+
+	@Test
+	@WithMockUser
+	void findMessageWhenUserThenSuccess() {
+		assertThat(this.messages.findMessage()).isEqualTo("Hello User!");
+	}
+
+	// -- findSecretMessage ---
+
+	@Test
+	@WithUnauthenticatedUser
+	void findSecretMessageWhenNotAuthenticatedThenDenied() {
+		assertThatExceptionOfType(AccessDeniedException.class).isThrownBy(this.messages::findSecretMessage);
+	}
+
+	@Test
+	@WithMockUser
+	void findSecretMessageWhenNotAuthorizedThenDenied() {
+		assertThatExceptionOfType(AccessDeniedException.class).isThrownBy(this.messages::findSecretMessage);
+	}
+
+	@Test
+	@WithMockUser(roles = "ADMIN")
+	void findSecretMessageWhenAuthorizedThenSuccess() {
+		assertThat(this.messages.findSecretMessage()).isEqualTo("Hello Admin!");
+	}
+
+	@Target({ ElementType.METHOD, ElementType.TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@WithSecurityContext(factory = WithUnauthenticatedUserSecurityContextFactory.class)
+	private @interface WithUnauthenticatedUser {
+
+	}
+
+	private static final class WithUnauthenticatedUserSecurityContextFactory
+			implements WithSecurityContextFactory<WithUnauthenticatedUser> {
+
+		@Override
+		public SecurityContext createSecurityContext(WithUnauthenticatedUser annotation) {
+			TestingAuthenticationToken token = new TestingAuthenticationToken("user", "password");
+			token.setAuthenticated(false);
+			return new SecurityContextImpl(token);
+		}
+
+	}
+
+}

settings.gradle

@@ -64,6 +64,7 @@ include ":servlet:spring-boot:java:oauth2:resource-server:multi-tenancy"
 include ":servlet:spring-boot:java:oauth2:resource-server:opaque"
 include ":servlet:spring-boot:java:oauth2:resource-server:static"
 include ":servlet:spring-boot:java:oauth2:webclient"
+include ":servlet:spring-boot:java:observability"
 include ":servlet:spring-boot:java:saml2:login"
 include ":servlet:spring-boot:java:saml2:login-single-tenant"
 include ":servlet:spring-boot:java:saml2:refreshable-metadata"