Develop Reference

SnapStart function priming - Doesn't seem to be working

I’m somewhat new to Kotlin/Java, but I have been using AWS Lambda for several years now (all Python and Node). I’ve been trying to “successfully” enable SnapStart on a SpringBoot Lambda using Kotlin running on java11 corretto (the only runtime supported currently), but it doesn’t seem to be working as I would have expected.
I have hooked into the CRaC lifecycle methods beforeCheckpoint and afterRestore. In beforeCheckpoint I’ve initialized the SpringBoot application and I can see it in the deployment logs (AWS creates log streams for the deployment phase with SnapStart lambdas).
However, the concerning thing is I’m also seeing the SpringBoot app get initialized in the function invocation logs too. I would have expected that to only happen during the deployment/initialization phase when the snapshot is being created. As a result I’m not really seeing a tremendous improvement on latency or overall.
Any ideas why this is happening?

I ran into essentially the same issue (with Java instead of Kotlin) and the solution was to switch the runtime->handler from
org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler
to
org.springframework.cloud.function.adapter.aws.FunctionInvoker::handleRequest

It would probably be worth mentioning that as of 2023-02-20 SnapStart isn't engaged for $LATEST version of an AWS Lambda function, i.e. make sure you are invoking a particular published version. Otherwise, Best practices for working with Lambda SnapStart article says that the main performance killers are dynamically loaded classes, and network connections that need to be re-established from time to time.
From Snapstart Integration issue raised for Spring Cloud Function on GitHub I tend to think that switching to org.springframework.cloud.function.adapter.aws.FunctionInvoker probably somewhat helps, but doesn't address the performance challenges mentioned above. I'm not sure if I'm interpreting olegz's advice correctly, but what worked best so far for my AWS lambda function built with Spring Boot/Spring Cloud Function is a "warm-up" config. It hooks into the CRaC lifecycle via beforeCheckpoint() and issues dummy requests to S3 and DynamoDB before the VM snapshot is made. This way most dynamically-loaded classes are pre-loaded, and network connections are pre-established, before any subsequent function invocation takes place.
package eu.mycompany.mysamplesystem.attachmentstore.configuration;
import com.amazonaws.services.lambda.runtime.events.S3Event;
import eu.mycompany.mysamplesystem.attachmentstore.handlers.MainEventHandler;
import lombok.extern.slf4j.Slf4j;
import org.crac.Core;
import org.crac.Resource;
import org.springframework.context.annotation.Configuration;
import software.amazon.awssdk.services.s3.model.NoSuchKeyException;
import java.util.ArrayList;
import java.util.List;
#Configuration
#Slf4j
public class WarmUpConfig implements Resource {
private final MainEventHandler mainEventHandler;
public WarmUpConfig(final MainEventHandler mainEventHandler) {
Core.getGlobalContext().register(this);
this.mainEventHandler = mainEventHandler;
}
#Override
public void beforeCheckpoint(org.crac.Context<? extends Resource> context) {
log.debug("Warm-up MainEventHandler by issuing dummy requests");
dummyS3Invocation();
dummyDynamoDbInvocation();
}
#Override
public void afterRestore(org.crac.Context<? extends Resource> context) {
}
public void dummyS3Invocation() {
S3Event s3Event = generateWarmUpEvent("ObjectCreated:Put");
try {
mainEventHandler.handleRequest(s3Event, null);
throw new IllegalStateException("Warm-up event processing should have reached S3 and failed with S3Exception");
} catch (NoSuchKeyException e) {
log.debug("S3Exception is expected, since it is a warm-up");
}
}
public void dummyDynamoDbInvocation() {
S3Event s3Event = generateWarmUpEvent("ObjectRemoved:Delete");
mainEventHandler.handleRequest(s3Event, null);
}
private S3Event generateWarmUpEvent(String eventName) {
S3Event.S3BucketEntity s3BucketEntity = new S3Event.S3BucketEntity("hopefully_non_existing_bucket", null, null);
S3Event.S3ObjectEntity s3ObjectEntity = new S3Event.S3ObjectEntity("hopefully/non/existing.key", 0L, null, null, null);
S3Event.S3Entity s3Entity = new S3Event.S3Entity(null, s3BucketEntity, s3ObjectEntity, null);
List<S3Event.S3EventNotificationRecord> records = new ArrayList<>();
records.add(new S3Event.S3EventNotificationRecord(null, eventName, null, null, null, null, null, s3Entity, null));
return new S3Event(records);
}
}
P.S.: The MainEventHandler is basically the entry point to all the business logic exposed by the Function.
#SpringBootApplication
#RequiredArgsConstructor
public class Lambda {
private final MainEventHandler mainEventHandler;
public static void main(String... args) {
SpringApplication.run(Lambda.class, args);
}
#Bean
public Function<Message<S3Event>, String> defaultFunctionLambda() {
return message -> {
Context context = message.getHeaders().get("aws-context", Context.class);
return mainEventHandler.handleRequest(message.getPayload(), context);
};
}
}

How to install or register a Saxon HE 10.3 Configuration? Configuration is not being used

I'm trying to use a custom Configuration for saxon HE 10.3.
The Configuration is not being used. Presumably the config needs to be registered or installed? But how?
Here's my code:
final Configuration config = new net.sf.saxon.Configuration();
/**/ config.setLocalizerFactory(new LocalizerFactory() {
public Numberer getNumberer(final String language, final String country) {
if (language.equals("de")) {
return Numberer_de.getInstance();
} else {
return null;
}
}
});
net.sf.saxon.Transform.main(new String[] {
"-s:source.xml",
"-xsl:stylesheet.xslt",
"-o:result.txt"
});

You really don't want to be running net.sf.saxon.Transform.main from a Java application: use either the s9api or JAXP transformation APIs. The net.sf.saxon.Transform.main interface is designed for use from the command line, and it can therefore only modify the configuration through command line switches. It also has drawbacks like shutting down the Java VM if the transformation fails.
There is a workaround, which is to use the -init option on the command line to trigger user-supplied initialisation code (which has access to the Configuration object), but that's only really digging yourself deeper into your hole. I'd recommend switching to the s9api API.
Documentation: https://saxonica.com/documentation/index.html#!using-xsl/embedding

If you want to change the configuration when running Saxon from the command line, as Michael said, there is the -init option to pass in the name of a class implementing the Initializer interface https://saxonica.com/documentation/index.html#!javadoc/net.sf.saxon.lib/Initializer so you would use roughly e.g.
package com.example;
import net.sf.saxon.option.local.Numberer_de;
import net.sf.saxon.lib.Initializer;
import net.sf.saxon.Configuration;
import net.sf.saxon.lib.LocalizerFactory;
import net.sf.saxon.lib.Numberer;
import javax.xml.transform.TransformerException;
public class MyInitializer implements Initializer {
public override void initialize(Configuration config) throws TransformerException {
config.setLocalizerFactory(new LocalizerFactory() {
public Numberer getNumberer(final String language, final String country) {
if (language.equals("de")) {
return Numberer_de.getInstance();
} else {
return null;
}
}
});
}
}
compile that, put it on the classpath and then run e.g. java -cp saxon-he-10.3.jar;com/example/MyInitializer;net/sf/saxon/option/local/Numberer_de net.sf.saxon.Transform -init:com.example.MyInitializer -s:source.xml -xsl:stylesheet.xslt -o:result.txt.
Or you can subclass net.sf.saxon.Transform.
On the other hand, if you don't want to run Saxon from the command line but from the JAXP API then I think one approach is to create the Configuration e.g.
Configuration config = new Configuration();
config.setLocalizerFactory(new LocalizerFactory() {
public Numberer getNumberer(final String language, final String country) {
if (language.equals("de")) {
return Numberer_de.getInstance();
} else {
return null;
}
}
});
TransformerFactory transformerFactory = new TransformerFactoryImpl(config);
Templates templates = transformerFactory.newTemplates(xsltSource);

What was missing, was how to inject the Config. This worked for me:
import net.sf.saxon.Configuration;
import net.sf.saxon.TransformerFactoryImpl;
import net.sf.saxon.lib.Feature;
final TransformerFactoryImpl factory = (TransformerFactoryImpl) TransformerFactory.newInstance();
factory.getProcessor().setConfigurationProperty(Feature.CONFIGURATION, config);

Broadleaf Commerce Embedded Solr cannot run with root user

I download a fresh 6.1 broadleaf-commerce and run my local machine via java -javaagent:./admin/target/agents/spring-instrument.jar -jar admin/target/admin.jar successfully on mine macbook. But in my centos 7 I run sudo java -javaagent:./admin/target/agents/spring-instrument.jar -jar admin/target/admin.jar with following error
2020-10-12 13:20:10.838 INFO 2481 --- [ main] c.b.solr.autoconfigure.SolrServer : Syncing solr config file: jar:file:/home/mynewuser/seafood-broadleaf/admin/target/admin.jar!/BOOT-INF/lib/broadleaf-boot-starter-solr-2.2.1-GA.jar!/solr/standalone/solrhome/configsets/fulfillment_order/conf/solrconfig.xml to: /tmp/solr-7.7.2/solr-7.7.2/server/solr/configsets/fulfillment_order/conf/solrconfig.xml
*** [WARN] *** Your Max Processes Limit is currently 62383.
It should be set to 65000 to avoid operational disruption.
If you no longer wish to see this warning, set SOLR_ULIMIT_CHECKS to false in your profile or solr.in.sh
WARNING: Starting Solr as the root user is a security risk and not considered best practice. Exiting.
Please consult the Reference Guide. To override this check, start with argument '-force'
2020-10-12 13:20:11.021 ERROR 2481 --- [ main] c.b.solr.autoconfigure.SolrServer : Problem starting Solr
Here is the source code of solr configuration, I believe it is the place to change the configuration to run with the argument -force in programming way.
package com.community.core.config;
import org.apache.solr.client.solrj.SolrClient;
import org.apache.solr.client.solrj.impl.HttpSolrClient;
import org.broadleafcommerce.core.search.service.SearchService;
import org.broadleafcommerce.core.search.service.solr.SolrConfiguration;
import org.broadleafcommerce.core.search.service.solr.SolrSearchServiceImpl;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
/**
*
*
* #author Phillip Verheyden (phillipuniverse)
*/
#Component
public class ApplicationSolrConfiguration {
#Value("${solr.url.primary}")
protected String primaryCatalogSolrUrl;
#Value("${solr.url.reindex}")
protected String reindexCatalogSolrUrl;
#Value("${solr.url.admin}")
protected String adminCatalogSolrUrl;
#Bean
public SolrClient primaryCatalogSolrClient() {
return new HttpSolrClient.Builder(primaryCatalogSolrUrl).build();
}
#Bean
public SolrClient reindexCatalogSolrClient() {
return new HttpSolrClient.Builder(reindexCatalogSolrUrl).build();
}
#Bean
public SolrClient adminCatalogSolrClient() {
return new HttpSolrClient.Builder(adminCatalogSolrUrl).build();
}
#Bean
public SolrConfiguration blCatalogSolrConfiguration() throws IllegalStateException {
return new SolrConfiguration(primaryCatalogSolrClient(), reindexCatalogSolrClient(), adminCatalogSolrClient());
}
#Bean
protected SearchService blSearchService() {
return new SolrSearchServiceImpl();
}
}

Let me preface this by saying you would be better off simply not starting the application as root. If you are in Docker, you can use the USER command to switch to a non-root user.
The Solr server startup in Broadleaf Community is done programmatically via the broadleaf-boot-starter-solr dependency. This is the wrapper around Solr that ties it to the Spring lifecycle. All of the real magic happens in the com.broadleafcommerce.solr.autoconfigure.SolrServer class.
In that class, you will see a startSolr() method. This method is what adds startup arguments to Solr.
In your case, you will need to mostly copy this method wholesale and use cmdLine.addArgument(...) to add additional arguments. Example:
class ForceStartupSolrServer extends SolrServer {
public ForceStartupSolrServer(SolrProperties props) {
super(props);
}
protected void startSolr() {
if (!isRunning()) {
if (!downloadSolrIfApplicable()) {
throw new IllegalStateException("Could not download or expand Solr, see previous logs for more information");
}
stopSolr();
synchConfig();
{
CommandLine cmdLine = new CommandLine(getSolrCommand());
cmdLine.addArgument("start");
cmdLine.addArgument("-p");
cmdLine.addArgument(Integer.toString(props.getPort()));
// START MODIFICATION
cmdLine.addArgument("-force");
// END MODIFICATION
Executor executor = new DefaultExecutor();
PumpStreamHandler streamHandler = new PumpStreamHandler(System.out);
streamHandler.setStopTimeout(1000);
executor.setStreamHandler(streamHandler);
try {
executor.execute(cmdLine);
created = true;
checkCoreStatus();
} catch (IOException e) {
LOG.error("Problem starting Solr", e);
}
}
}
}
}
Then create an #Configuration class to override the blAutoSolrServer bean created by SolrAutoConfiguration (note the specific package requirement for org.broadleafoverrides.config):
package org.broadleafoverrides.config;
public class OverrideConfiguration {
#Bean
public ForceStartupSolrServer blAutoSolrServer(SolrProperties props) {
return new ForceStartupSolrServer(props);
}
}

wildfly: reading properties from configuration directory

I'm trying to read deployment specific information from a properties file in my wildfly configuration folder. I tried this:
#Singleton
#Startup
public class DeploymentConfiguration {
protected Properties props;
#PostConstruct
public void readConfig() {
props = new Properties();
try {
props.load(getClass().getClassLoader().getResourceAsStream("my.properties"));
} catch (IOException e) {
// ... whatever
}
}
But apparently this is not working since the configuration folder is not in the classpath anymore. Now I can't find an easy way to do it. My favorite would be something like this:
#InjectProperties("my.properties")
protected Properties props;
The only solution I found on the web so far involves making my own OSGi module, but I believe there must be an easier way to do it (one without OSGi!). Can anyone show me how?

If you want to explicitly read a file from the configuration directory (e.g. $WILDFLY_HOME/standalone/configuration or domain/configuration) there's a system property with the path in it. Simply do System.getProperty("jboss.server.config.dir"); and append your file name to that to get the file.
You wouldn't read it as a resource though, so...
String fileName = System.getProperty("jboss.server.config.dir") + "/my.properties";
try(FileInputStream fis = new FileInputStream(fileName)) {
properties.load(fis);
}
Then the file would be loaded for you.
Also, since WildFly doesn't ship with OSGi support anymore, I don't know how creating an OSGi module would help you here.

Here is a full example using just CDI, taken from this site.
Create and populate a properties file inside the WildFly configuration folder
$ echo 'docs.dir=/var/documents' >> .standalone/configuration/application.properties
Add a system property to the WildFly configuration file.
$ ./bin/jboss-cli.sh --connect
[standalone#localhost:9990 /] /system-property=application.properties:add(value=${jboss.server.config.dir}/application.properties)
This will add the following to your server configuration file (standalone.xml or domain.xml):
<system-properties>
<property name="application.properties" value="${jboss.server.config.dir}/application.properties"/>
</system-properties>
Create the singleton session bean that loads and stores the application wide properties
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import javax.annotation.PostConstruct;
import javax.ejb.Singleton;
#Singleton
public class PropertyFileResolver {
private Logger logger = Logger.getLogger(PropertyFileResolver.class);
private String properties = new HashMap<>();
#PostConstruct
private void init() throws IOException {
//matches the property name as defined in the system-properties element in WildFly
String propertyFile = System.getProperty("application.properties");
File file = new File(propertyFile);
Properties properties = new Properties();
try {
properties.load(new FileInputStream(file));
} catch (IOException e) {
logger.error("Unable to load properties file", e);
}
HashMap hashMap = new HashMap<>(properties);
this.properties.putAll(hashMap);
}
public String getProperty(String key) {
return properties.get(key);
}
}
Create the CDI Qualifier. We will use this annotation on the Java variables we wish to inject into.
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import javax.inject.Qualifier;
#Qualifier
#Retention(RetentionPolicy.RUNTIME)
#Target({ ElementType.METHOD, ElementType.FIELD, ElementType.CONSTRUCTOR })
public #interface ApplicationProperty {
// no default meaning a value is mandatory
#Nonbinding
String name();
}
Create the producer method; this generates the object to be injected
import javax.enterprise.inject.Produces;
import javax.enterprise.inject.spi.InjectionPoint;
import javax.inject.Inject;
public class ApplicaitonPropertyProducer {
#Inject
private PropertyFileResolver fileResolver;
#Produces
#ApplicationProperty(name = "")
public String getPropertyAsString(InjectionPoint injectionPoint) {
String propertyName = injectionPoint.getAnnotated().getAnnotation(ApplicationProperty.class).name();
String value = fileResolver.getProperty(propertyName);
if (value == null || propertyName.trim().length() == 0) {
throw new IllegalArgumentException("No property found with name " + value);
}
return value;
}
#Produces
#ApplicationProperty(name="")
public Integer getPropertyAsInteger(InjectionPoint injectionPoint) {
String value = getPropertyAsString(injectionPoint);
return value == null ? null : Integer.valueOf(value);
}
}
Lastly inject the property into one of your CDI beans
import javax.ejb.Stateless;
import javax.inject.Inject;
#Stateless
public class MySimpleEJB {
#Inject
#ApplicationProperty(name = "docs.dir")
private String myProperty;
public String getProperty() {
return myProperty;
}
}

The simplest thing you can do is to run standalone.sh with a -P option referencing your properties file (you need a URL file:/path/to/my.properties, or put the file in $WILDFLY_HOME/bin).
Then all properties from the file will be loaded as system properties.
For injecting configuration properties into your application classes, have a look at DeltaSpike Configuration, which supports different property sources like system properties, environment variables, JNDI entries and hides the specific source from your application.
Alternatively, to avoid setting system properties (which will be global in the sense of being visible to all applications deployed to your WildFly instance), you can also define a custom property source for DeltaSpike reading a properties file from any given location, and these properties will be local to your application.

It sounds like the problem you are trying to solve is managing different (but probably similar) configuration files for running your application in different environments (ie, Production, QA, or even different customers). If that is the case, take a look at Jfig http://jfig.sourceforge.net/ . It would obviate the need for storing property files outside your classpath (but you still could).
What is needed is a hierarchical approach to configuration files. The ninety percent of configuration values that do not change can be maintained in a base file. The other ten percent (or less) may be maintained in their own distinct configuration file. At run time, the files are layered on top of each other to provide a flexible, manageable configuration. For example, in a development environment myhost.config.xml combines with dev.config.xml and base.config.xml to form my unique configuration.
Each configuration file may then be maintained in version control as they have unique names. Only the base files need to be modified when base values change, and it is easy to see the difference between versions. Another major benefit is that changes to the base configuration file will be exhaustively tested before deployment.

InputStream in = null;
File confDir = new File(System.getProperty("jboss.server.config.dir"));
File fileProp = new File(confDir, "my.properties");
try{
//teste fileProp.exists etc.
in = new FileInputStream(fileProp);
Properties properties = new Properties();
properties.load(in);
//You should throws or handle FileNotFoundException and IOException
}finally{
try{
in.close();
}catch(Exception ignored){
}
}

To avoid this kind of problem the issue is to set the jboss.server.config.dir in VM arguments like that :
-Djboss.server.config.dir="[jboss_repository]/server/[default-all-standard-standalone]/conf" –server

If you have in standalone.xml property:
<property name="my.properties" value="propertyValue"/>
you can wasily read it with:
static final String MY_PROPERTY = System.getProperty("my.properties");
Or if you specify context param in web.xml like:
<context-param>
<param-name>MyProperty</param-name>
<param-value>MyPropertyValue</param-value>
</context-param>
You can read it in Java bean:
String myProperty= getServletContext().getInitParameter("MyProperty");

How to log the active configuration in a Spring Boot application?

I would really like to use YAML config for Spring Boot, as I find it quite readable and useful to have a single file showing what properties are active in my different profiles. Unfortunately, I'm finding that setting properties in application.yml can be rather fragile.
Things like using a tab instead of spaces will cause properties to not exist (without warnings as far as I can see), and all too often I find that my active profiles are not being set, due to some unknown issue with my YAML.
So I was wondering whether there are any hooks that would enable me to get hold of the currently active profiles and properties, so that I could log them.
Similarly, is there a way to cause start-up to fail if the application.yml contains errors? Either that or a means for me to validate the YAML myself, so that I could kill the start-up process.

In addition to other answers: logging active properties on context refreshed event.
Java 8
package mypackage;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.stereotype.Component;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
#Slf4j
#Component
public class AppContextEventListener {
#EventListener
public void handleContextRefreshed(ContextRefreshedEvent event) {
printActiveProperties((ConfigurableEnvironment) event.getApplicationContext().getEnvironment());
}
private void printActiveProperties(ConfigurableEnvironment env) {
System.out.println("************************* ACTIVE APP PROPERTIES ******************************");
List<MapPropertySource> propertySources = new ArrayList<>();
env.getPropertySources().forEach(it -> {
if (it instanceof MapPropertySource && it.getName().contains("applicationConfig")) {
propertySources.add((MapPropertySource) it);
}
});
propertySources.stream()
.map(propertySource -> propertySource.getSource().keySet())
.flatMap(Collection::stream)
.distinct()
.sorted()
.forEach(key -> {
try {
System.out.println(key + "=" + env.getProperty(key));
} catch (Exception e) {
log.warn("{} -> {}", key, e.getMessage());
}
});
System.out.println("******************************************************************************");
}
}
Kotlin
package mypackage
import mu.KLogging
import org.springframework.context.event.ContextRefreshedEvent
import org.springframework.context.event.EventListener
import org.springframework.core.env.ConfigurableEnvironment
import org.springframework.core.env.MapPropertySource
import org.springframework.stereotype.Component
#Component
class AppContextEventListener {
companion object : KLogging()
#EventListener
fun handleContextRefreshed(event: ContextRefreshedEvent) {
printActiveProperties(event.applicationContext.environment as ConfigurableEnvironment)
}
fun printActiveProperties(env: ConfigurableEnvironment) {
println("************************* ACTIVE APP PROPERTIES ******************************")
env.propertySources
.filter { it.name.contains("applicationConfig") }
.map { it as EnumerablePropertySource<*> }
.map { it -> it.propertyNames.toList() }
.flatMap { it }
.distinctBy { it }
.sortedBy { it }
.forEach { it ->
try {
println("$it=${env.getProperty(it)}")
} catch (e: Exception) {
logger.warn("$it -> ${e.message}")
}
}
println("******************************************************************************")
}
}
Output like:
************************* ACTIVE APP PROPERTIES ******************************
server.port=3000
spring.application.name=my-app
...
2017-12-29 13:13:32.843 WARN 36252 --- [ main] m.AppContextEventListener : spring.boot.admin.client.service-url -> Could not resolve placeholder 'management.address' in value "http://${management.address}:${server.port}"
...
spring.datasource.password=
spring.datasource.url=jdbc:postgresql://localhost/my_db?currentSchema=public
spring.datasource.username=db_user
...
******************************************************************************

I had the same problem, and wish there was a debug flag that would tell the profile processing system to spit out some useful logging. One possible way of doing it would be to register an event listener for your application context, and print out the profiles from the environment. I haven't tried doing it this way myself, so your mileage may vary. I think maybe something like what's outlined here:
How to add a hook to the application context initialization event?
Then you'd do something like this in your listener:
System.out.println("Active profiles: " + Arrays.toString(ctxt.getEnvironment().getActiveProfiles()));
Might be worth a try. Another way you could probably do it would be to declare the Environment to be injected in the code where you need to print the profiles. I.e.:
#Component
public class SomeClass {
#Autowired
private Environment env;
...
private void dumpProfiles() {
// Print whatever needed from env here
}
}

Actuator /env service displays properties, but it doesn't displays which property value is actually active. Very often you may want to override your application properties with
profile-specific application properties
command line arguments
OS environment variables
Thus you will have the same property and different values in several sources.
Snippet bellow prints active application properties values on startup:
#Configuration
public class PropertiesLogger {
private static final Logger log = LoggerFactory.getLogger(PropertiesLogger.class);
#Autowired
private AbstractEnvironment environment;
#PostConstruct
public void printProperties() {
log.info("**** APPLICATION PROPERTIES SOURCES ****");
Set<String> properties = new TreeSet<>();
for (PropertiesPropertySource p : findPropertiesPropertySources()) {
log.info(p.toString());
properties.addAll(Arrays.asList(p.getPropertyNames()));
}
log.info("**** APPLICATION PROPERTIES VALUES ****");
print(properties);
}
private List<PropertiesPropertySource> findPropertiesPropertySources() {
List<PropertiesPropertySource> propertiesPropertySources = new LinkedList<>();
for (PropertySource<?> propertySource : environment.getPropertySources()) {
if (propertySource instanceof PropertiesPropertySource) {
propertiesPropertySources.add((PropertiesPropertySource) propertySource);
}
}
return propertiesPropertySources;
}
private void print(Set<String> properties) {
for (String propertyName : properties) {
log.info("{}={}", propertyName, environment.getProperty(propertyName));
}
}
}

If application.yml contains errors it will cause a failure on startup. I guess it depends what you mean by "error" though. Certainly it will fail if the YAML is not well formed. Also if you are setting #ConfigurationProperties that are marked as ignoreInvalidFields=true for instance, or if you set a value that cannot be converted. That's a pretty wide range of errors.
The active profiles will probably be logged on startup by the Environment implementation (but in any case it's easy for you to grab that and log it in your launcher code - the toString() of teh Environment will list the active profiles I think). Active profiles (and more) are also available in the /env endpoint if you add the Actuator.

In case you want to get the active profiles before initializing the beans/application, the only way I found is registering a custom Banner in your SpringBootServletInitializer/SpringApplication (i.e. ApplicationWebXml in a JHipster application).
e.g.
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder builder)
{
// set a default to use when no profile is configured.
DefaultProfileUtil.addDefaultProfile(builder.application());
return builder.sources(MyApp.class).banner(this::printBanner);
}
/** Custom 'banner' to obtain early access to the Spring configuration to validate and debug it. */
private void printBanner(Environment env, Class<?> sourceClass, PrintStream out)
{
if (env.getProperty("spring.datasource.url") == null)
{
throw new RuntimeException(
"'spring.datasource.url' is not configured! Check your configuration files and the value of 'spring.profiles.active' in your launcher.");
}
...
}