org.springframework.boot.context.ApplicationPidFileWriter Maven / Gradle / Ivy
/*
* Copyright 2012-2020 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 org.springframework.boot.context;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
import org.springframework.boot.context.event.ApplicationPreparedEvent;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.boot.context.event.SpringApplicationEvent;
import org.springframework.boot.system.ApplicationPid;
import org.springframework.boot.system.SystemProperties;
import org.springframework.context.ApplicationListener;
import org.springframework.core.Ordered;
import org.springframework.core.env.Environment;
import org.springframework.util.Assert;
/**
* An {@link ApplicationListener} that saves application PID into file. This application
* listener will be triggered exactly once per JVM, and the file name can be overridden at
* runtime with a System property or environment variable named "PIDFILE" (or "pidfile")
* or using a {@code spring.pid.file} property in the Spring {@link Environment}.
*
* If PID file can not be created no exception is reported. This behavior can be changed
* by assigning {@code true} to System property or environment variable named
* {@code PID_FAIL_ON_WRITE_ERROR} (or "pid_fail_on_write_error") or to
* {@code spring.pid.fail-on-write-error} property in the Spring {@link Environment}.
*
* Note: access to the Spring {@link Environment} is only possible when the
* {@link #setTriggerEventType(Class) triggerEventType} is set to
* {@link ApplicationEnvironmentPreparedEvent}, {@link ApplicationReadyEvent}, or
* {@link ApplicationPreparedEvent}.
*
* @author Jakub Kubrynski
* @author Dave Syer
* @author Phillip Webb
* @author Tomasz Przybyla
* @author Madhura Bhave
* @since 2.0.0
*/
public class ApplicationPidFileWriter implements ApplicationListener, Ordered {
private static final Log logger = LogFactory.getLog(ApplicationPidFileWriter.class);
private static final String DEFAULT_FILE_NAME = "application.pid";
private static final List FILE_PROPERTIES;
static {
List properties = new ArrayList<>();
properties.add(new SpringProperty("spring.pid.", "file"));
properties.add(new SpringProperty("spring.", "pidfile"));
properties.add(new SystemProperty("PIDFILE"));
FILE_PROPERTIES = Collections.unmodifiableList(properties);
}
private static final List FAIL_ON_WRITE_ERROR_PROPERTIES;
static {
List properties = new ArrayList<>();
properties.add(new SpringProperty("spring.pid.", "fail-on-write-error"));
properties.add(new SystemProperty("PID_FAIL_ON_WRITE_ERROR"));
FAIL_ON_WRITE_ERROR_PROPERTIES = Collections.unmodifiableList(properties);
}
private static final AtomicBoolean created = new AtomicBoolean();
private int order = Ordered.HIGHEST_PRECEDENCE + 13;
private final File file;
private Class triggerEventType = ApplicationPreparedEvent.class;
/**
* Create a new {@link ApplicationPidFileWriter} instance using the filename
* 'application.pid'.
*/
public ApplicationPidFileWriter() {
this(new File(DEFAULT_FILE_NAME));
}
/**
* Create a new {@link ApplicationPidFileWriter} instance with a specified filename.
* @param filename the name of file containing pid
*/
public ApplicationPidFileWriter(String filename) {
this(new File(filename));
}
/**
* Create a new {@link ApplicationPidFileWriter} instance with a specified file.
* @param file the file containing pid
*/
public ApplicationPidFileWriter(File file) {
Assert.notNull(file, "File must not be null");
this.file = file;
}
/**
* Sets the type of application event that will trigger writing of the PID file.
* Defaults to {@link ApplicationPreparedEvent}. NOTE: If you use the
* {@link org.springframework.boot.context.event.ApplicationStartingEvent} to trigger
* the write, you will not be able to specify the PID filename in the Spring
* {@link Environment}.
* @param triggerEventType the trigger event type
*/
public void setTriggerEventType(Class triggerEventType) {
Assert.notNull(triggerEventType, "Trigger event type must not be null");
this.triggerEventType = triggerEventType;
}
@Override
public void onApplicationEvent(SpringApplicationEvent event) {
if (this.triggerEventType.isInstance(event) && created.compareAndSet(false, true)) {
try {
writePidFile(event);
}
catch (Exception ex) {
String message = String.format("Cannot create pid file %s", this.file);
if (failOnWriteError(event)) {
throw new IllegalStateException(message, ex);
}
logger.warn(message, ex);
}
}
}
private void writePidFile(SpringApplicationEvent event) throws IOException {
File pidFile = this.file;
String override = getProperty(event, FILE_PROPERTIES);
if (override != null) {
pidFile = new File(override);
}
new ApplicationPid().write(pidFile);
pidFile.deleteOnExit();
}
private boolean failOnWriteError(SpringApplicationEvent event) {
String value = getProperty(event, FAIL_ON_WRITE_ERROR_PROPERTIES);
return Boolean.parseBoolean(value);
}
private String getProperty(SpringApplicationEvent event, List candidates) {
for (Property candidate : candidates) {
String value = candidate.getValue(event);
if (value != null) {
return value;
}
}
return null;
}
public void setOrder(int order) {
this.order = order;
}
@Override
public int getOrder() {
return this.order;
}
/**
* Reset the created flag for testing purposes.
*/
protected static void reset() {
created.set(false);
}
/**
* Provides access to a property value.
*/
private interface Property {
String getValue(SpringApplicationEvent event);
}
/**
* {@link Property} obtained from Spring's {@link Environment}.
*/
private static class SpringProperty implements Property {
private final String prefix;
private final String key;
SpringProperty(String prefix, String key) {
this.prefix = prefix;
this.key = key;
}
@Override
public String getValue(SpringApplicationEvent event) {
Environment environment = getEnvironment(event);
if (environment == null) {
return null;
}
return environment.getProperty(this.prefix + this.key);
}
private Environment getEnvironment(SpringApplicationEvent event) {
if (event instanceof ApplicationEnvironmentPreparedEvent) {
return ((ApplicationEnvironmentPreparedEvent) event).getEnvironment();
}
if (event instanceof ApplicationPreparedEvent) {
return ((ApplicationPreparedEvent) event).getApplicationContext().getEnvironment();
}
if (event instanceof ApplicationReadyEvent) {
return ((ApplicationReadyEvent) event).getApplicationContext().getEnvironment();
}
return null;
}
}
/**
* {@link Property} obtained from {@link SystemProperties}.
*/
private static class SystemProperty implements Property {
private final String[] properties;
SystemProperty(String name) {
this.properties = new String[] { name.toUpperCase(Locale.ENGLISH), name.toLowerCase(Locale.ENGLISH) };
}
@Override
public String getValue(SpringApplicationEvent event) {
return SystemProperties.get(this.properties);
}
}
}