Add Docker-based Identity Provider

Issue gh-127

servlet/spring-boot/java/saml2/identity-provider/README.adoc

@@ -0,0 +1,51 @@
+= SAML 2.0 Login & Logout Sample
+
+This guide provides instructions on setting up this SAML 2.0 Login & Logout sample application.
+It uses https://simplesamlphp.org/[SimpleSAMLphp] as its asserting party.
+
+The sample application uses Spring Boot and the `spring-security-saml2-service-provider`
+module which is new in Spring Security 5.2.
+
+The https://docs.spring.io/spring-security/reference/servlet/saml2/logout.html[SAML 2.0 Logout feature] is new in Spring Security 5.6.
+
+== Goals
+
+=== SAML 2.0 Login
+
+`saml2Login()` provides a very simple implementation of a Service Provider that can receive a SAML 2.0 Response via the HTTP-POST and HTTP-REDIRECT bindings against the https://developer.okta.com/docs/guides/build-sso-integration/saml2/main/[Okta SAML 2.0 IDP] reference implementation.
+
+The following features are implemented in the MVP:
+
+1. Receive and validate a SAML 2.0 Response containing an assertion, and create a corresponding authentication in Spring Security
+2. Send a SAML 2.0 AuthNRequest to an Identity Provider
+3. Provide a framework for components used in SAML 2.0 authentication that can be swapped by configuration
+4. Work against the Okta SAML 2.0 IDP reference implementation
+
+=== SAML 2.0 Single Logout
+
+`saml2Logout()` supports RP- and AP-initiated SAML 2.0 Single Logout via the HTTP-POST and HTTP-REDIRECT bindings against the https://developer.okta.com/docs/guides/build-sso-integration/saml2/main/[Okta SAML 2.0 IDP] reference implementation.
+
+On this sample, the SAML 2.0 Logout is using the HTTP-POST binding.
+
+You can refer to the https://docs.spring.io/spring-security/reference/servlet/saml2/logout.html[reference documentation] for more details about the RP- and AP-initiated SAML 2.0 Logout.
+
+== Run the Sample
+
+=== Start up the Sample Boot Application
+```
+ ./gradlew :servlet:spring-boot:java:saml2:login:bootRun
+```
+
+=== Open a Browser
+
+http://localhost:8080/
+
+You will be redirect to the Okta SAML 2.0 IDP
+
+=== Type in your credentials
+
+```
+User: [email protected]
+Password: 12345678
+```
+

servlet/spring-boot/java/saml2/identity-provider/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'
+	runtimeOnly "org.springframework.boot:spring-boot-docker-compose"
+}
+
+tasks.withType(Test).configureEach {
+	useJUnitPlatform()
+
+}

servlet/spring-boot/java/saml2/identity-provider/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/saml2/identity-provider/gradle/libs.versions.toml

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

servlet/spring-boot/java/saml2/identity-provider/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.10.2-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists