software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/nginx/NginxSshDriver.java - brooklyn-library - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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
  *
  *     http://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.apache.brooklyn.entity.proxy.nginx;

 import static java.lang.String.format;

 import java.util.List;
 import java.util.concurrent.atomic.AtomicLong;

 import org.apache.brooklyn.api.entity.drivers.downloads.DownloadResolver;
 import org.apache.brooklyn.api.location.Location;
 import org.apache.brooklyn.api.location.OsDetails;
 import org.apache.brooklyn.api.mgmt.ManagementContext;
 import org.apache.brooklyn.core.entity.Attributes;
 import org.apache.brooklyn.core.entity.EntityInternal;
 import org.apache.brooklyn.core.entity.lifecycle.Lifecycle;
 import org.apache.brooklyn.entity.proxy.AbstractController;
 import org.apache.brooklyn.entity.software.base.AbstractSoftwareProcessSshDriver;
 import org.apache.brooklyn.entity.software.base.lifecycle.ScriptHelper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.apache.brooklyn.location.ssh.SshMachineLocation;
 import org.apache.brooklyn.util.collections.MutableMap;
 import org.apache.brooklyn.util.core.task.DynamicTasks;
 import org.apache.brooklyn.util.core.task.Tasks;
 import org.apache.brooklyn.util.core.task.ssh.SshTasks;
 import org.apache.brooklyn.util.core.task.ssh.SshTasks.OnFailingTask;
 import org.apache.brooklyn.util.exceptions.Exceptions;
 import org.apache.brooklyn.util.net.Networking;
 import org.apache.brooklyn.util.ssh.BashCommands;
 import org.apache.brooklyn.util.stream.Streams;
 import org.apache.brooklyn.util.text.Strings;

 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;

 /**
  * Start a {@link NginxController} in a {@link Location} accessible over ssh.
  */
 public class NginxSshDriver extends AbstractSoftwareProcessSshDriver implements NginxDriver {

     // TODO An alternative way of installing nginx is described at:
     //   http://sjp.co.nz/posts/building-nginx-for-debian-systems/
     // It's use of `apt-get source nginx` and `apt-get build-dep nginx` makes
     // it look higher level and therefore more appealing.

     public static final Logger log = LoggerFactory.getLogger(NginxSshDriver.class);
     public static final String NGINX_PID_FILE = "logs/nginx.pid";

     private boolean customizationCompleted = false;

     public NginxSshDriver(NginxControllerImpl entity, SshMachineLocation machine) {
         super(entity, machine);

         entity.sensors().set(Attributes.LOG_FILE_LOCATION, getLogFileLocation());
         entity.sensors().set(NginxController.ACCESS_LOG_LOCATION, getAccessLogLocation());
         entity.sensors().set(NginxController.ERROR_LOG_LOCATION, getErrorLogLocation());
     }

     @Override
     public NginxControllerImpl getEntity() {
         return (NginxControllerImpl) super.getEntity();
     }

     public String getLogFileLocation() {
         return format("%s/console", getRunDir());
     }

     public String getAccessLogLocation() {
         String accessLog = entity.getConfig(NginxController.ACCESS_LOG_LOCATION);
         return format("%s/%s", getRunDir(), accessLog);
     }

     public String getErrorLogLocation() {
         String errorLog = entity.getConfig(NginxController.ERROR_LOG_LOCATION);
         return format("%s/%s", getRunDir(), errorLog);
     }

     /** By default Nginx writes the pid of the master process to {@code logs/nginx.pid} */
     @Override
     public String getPidFile() {
         return format("%s/%s", getRunDir(), NGINX_PID_FILE);
     }

     @Deprecated /** @deprecated since 0.7.0 use #getPort */
     public Integer getHttpPort() {
         return getEntity().getPort();
     }

     public Integer getPort() {
         return getEntity().getPort();
     }

     @Override
     public void rebind() {
         customizationCompleted = true;
     }

     @Override
     public void postLaunch() {
         entity.sensors().set(NginxController.PID_FILE, getRunDir() + "/" + AbstractSoftwareProcessSshDriver.PID_FILENAME);
         if (((AbstractController)entity).isSsl()) {
             entity.sensors().set(Attributes.HTTPS_PORT, getPort());
             ((EntityInternal)entity).sensors().remove(Attributes.HTTP_PORT);
         } else {
             entity.sensors().set(Attributes.HTTP_PORT, getPort());
             ((EntityInternal)entity).sensors().remove(Attributes.HTTPS_PORT);
         }
         super.postLaunch();
     }

     @Override
     public void install() {
         // inessential here, installation will fail later if it needs to sudo (eg if using port 80)
         DynamicTasks.queueIfPossible(SshTasks.dontRequireTtyForSudo(getMachine(), OnFailingTask.WARN_OR_IF_DYNAMIC_FAIL_MARKING_INESSENTIAL)).orSubmitAndBlock();

         List<String> nginxUrls = resolver.getTargets();
         String nginxSaveAs = resolver.getFilename();

         boolean sticky = ((NginxController) entity).isSticky();
         boolean isMac = getMachine().getOsDetails().isMac();

         MutableMap<String, String> installGccPackageFlags = MutableMap.of(
                 "onlyifmissing", "gcc",
                 "yum", "gcc",
                 "apt", "gcc",
                 "zypper", "gcc",
                 "port", null);
         MutableMap<String, String> installMakePackageFlags = MutableMap.of(
                 "onlyifmissing", "make",
                 "yum", "make",
                 "apt", "make",
                 "zypper", "make",
                 "port", null);
         MutableMap<String, String> installPackageFlags = MutableMap.of(
                 "yum", "openssl-devel pcre-devel",
                 "apt", "libssl-dev zlib1g-dev libpcre3-dev",
                 "zypper", "libopenssl-devel pcre-devel",
                 "port", null);

         String stickyModuleVersion = entity.getConfig(NginxController.STICKY_VERSION);
         DownloadResolver stickyModuleResolver = mgmt().getEntityDownloadsManager().newDownloader(
                 this, "stickymodule", ImmutableMap.of("addonversion", stickyModuleVersion));
         List<String> stickyModuleUrls = stickyModuleResolver.getTargets();
         String stickyModuleSaveAs = stickyModuleResolver.getFilename();
         String stickyModuleExpandedInstallDir = String.format("%s/src/%s", getExpandedInstallDir(),
                 stickyModuleResolver.getUnpackedDirectoryName("nginx-sticky-module-"+stickyModuleVersion));

         List<String> cmds = Lists.newArrayList();

         cmds.add(BashCommands.ifExecutableElse0("yum", BashCommands.sudo("yum -y install kernel-headers --disableexcludes=all")));
         cmds.add(BashCommands.INSTALL_TAR);
         cmds.add(BashCommands.alternatives(
                 BashCommands.ifExecutableElse0("apt-get", BashCommands.installPackage("build-essential")),
                 BashCommands.ifExecutableElse0("yum", BashCommands.sudo("yum -y --nogpgcheck groupinstall \"Development Tools\""))));
         cmds.add(BashCommands.installPackage(installGccPackageFlags, "nginx-prerequisites-gcc"));
         cmds.add(BashCommands.installPackage(installMakePackageFlags, "nginx-prerequisites-make"));
         cmds.add(BashCommands.installPackage(installPackageFlags, "nginx-prerequisites"));
         cmds.addAll(BashCommands.commandsToDownloadUrlsAs(nginxUrls, nginxSaveAs));

         String pcreExpandedInstallDirname = "";
         if (isMac) {
             String pcreVersion = entity.getConfig(NginxController.PCRE_VERSION);
             DownloadResolver pcreResolver = mgmt().getEntityDownloadsManager().newDownloader(
                     this, "pcre", ImmutableMap.of("addonversion", pcreVersion));
             List<String> pcreUrls = pcreResolver.getTargets();
             String pcreSaveAs = pcreResolver.getFilename();
             pcreExpandedInstallDirname = pcreResolver.getUnpackedDirectoryName("pcre-"+pcreVersion);

             // Install PCRE
             cmds.addAll(BashCommands.commandsToDownloadUrlsAs(pcreUrls, pcreSaveAs));
             cmds.add(format("mkdir -p %s/pcre-dist", getInstallDir()));
             cmds.add(format("tar xvzf %s", pcreSaveAs));
             cmds.add(format("cd %s", pcreExpandedInstallDirname));
             cmds.add(format("./configure --prefix=%s/pcre-dist", getInstallDir()));
             cmds.add("make");
             cmds.add("make install");
             cmds.add("cd ..");
         }

         cmds.add(format("tar xvzf %s", nginxSaveAs));
         cmds.add(format("cd %s", getExpandedInstallDir()));

         if (sticky) {
             // Latest versions of sticky module expand to a different folder than the file name.
             // Extract to folder set by us so we know where the sources are.
             cmds.add(format("mkdir -p %s", stickyModuleExpandedInstallDir));
             cmds.add(format("pushd %s", stickyModuleExpandedInstallDir));
             cmds.addAll(BashCommands.commandsToDownloadUrlsAs(stickyModuleUrls, stickyModuleSaveAs));
             cmds.add(format("tar --strip-component=1 -xvzf %s", stickyModuleSaveAs));
             cmds.add("popd");
         }

         // Note that for OS X, not including space after "-L" because broken in 10.6.8 (but fixed in 10.7.x)
         //      see http://trac.nginx.org/nginx/ticket/227
         String withLdOpt = entity.getConfig(NginxController.WITH_LD_OPT);
         if (isMac) withLdOpt = format("-L%s/pcre-dist/lib", getInstallDir()) + (Strings.isBlank(withLdOpt) ? "" : " " + withLdOpt);
         String withCcOpt = entity.getConfig(NginxController.WITH_CC_OPT);

         if (isMac) {
             // TODO Upgrade sticky module as soon as a fix for https://bitbucket.org/nginx-goodies/nginx-sticky-module-ng/issue/16/can-not-compile-on-macosx-yosemite
             // is released and remove this block.
             withCcOpt = (Strings.isBlank(withCcOpt) ? "" : (withCcOpt + " ")) + "-Wno-error";
         }

         StringBuilder configureCommand = new StringBuilder("./configure")
                 .append(format(" --prefix=%s/dist", getExpandedInstallDir()))
                 .append(" --with-http_ssl_module")
                 .append(sticky ? format(" --add-module=%s ", stickyModuleExpandedInstallDir) : "")
                 .append(!Strings.isBlank(withLdOpt) ? format(" --with-ld-opt=\"%s\"", withLdOpt) : "")
                 .append(!Strings.isBlank(withCcOpt) ? format(" --with-cc-opt=\"%s\"", withCcOpt) : "")
                 ;
         if (isMac) {
             configureCommand.append(" --with-pcre=")
                     .append(getInstallDir()).append("/").append(pcreExpandedInstallDirname);
         }

         cmds.addAll(ImmutableList.of(
                 "mkdir -p dist",
                 configureCommand.toString(),
                 "make install"));

         ScriptHelper script = newScript(INSTALLING)
                 .body.append(cmds)
                 .header.prepend("set -x")
                 .gatherOutput()
                 .failOnNonZeroResultCode(false);

         int result = script.execute();

         if (result != 0) {
             String notes = "likely an error building nginx. consult the brooklyn log ssh output for further details.\n"+
                     "note that this Brooklyn nginx driver compiles nginx from source. " +
                     "it attempts to install common prerequisites but this does not always succeed.\n";
             OsDetails os = getMachine().getOsDetails();
             if (os.isMac()) {
                 notes += "deploying to Mac OS X, you will require Xcode and Xcode command-line tools, and on " +
                         "some versions the pcre library (e.g. using macports, sudo port install pcre).\n";
             }
             if (os.isWindows()) {
                 notes += "this nginx driver is not designed for windows, unless cygwin is installed, and you are patient.\n";
             }
             if (getEntity().getApplication().getClass().getCanonicalName().startsWith("brooklyn.demo.")) {
                 // this is maybe naughty ... but since we use nginx in the first demo example,
                 // and since it's actually pretty complicated, let's give a little extra hand-holding
                 notes +=
                         "if debugging this is all a bit much and you just want to run a demo, " +
                         "you have two fairly friendly options.\n" +
                         "1. you can use a well known cloud, like AWS or Rackspace, where this should run " +
                         "in a tried-and-tested Ubuntu or CentOS environment, without any problems " +
                         "(and if it does let us know and we'll fix it!).\n"+
                         "2. or you can just use the demo without nginx, instead access the appserver instances directly.\n";
             }

             if (!script.getResultStderr().isEmpty()) {
                 notes += "\n" + "STDERR\n" + script.getResultStderr()+"\n";
                 Streams.logStreamTail(log, "STDERR of problem in "+Tasks.current(), Streams.byteArrayOfString(script.getResultStderr()), 1024);
             }
             if (!script.getResultStdout().isEmpty()) {
                 notes += "\n" + "STDOUT\n" + script.getResultStdout()+"\n";
                 Streams.logStreamTail(log, "STDOUT of problem in "+Tasks.current(), Streams.byteArrayOfString(script.getResultStdout()), 1024);
             }

             Tasks.setExtraStatusDetails(notes.trim());

             throw new IllegalStateException("Installation of nginx failed (shell returned non-zero result "+result+")");
         }
     }

     private ManagementContext mgmt() {
         return ((EntityInternal) entity).getManagementContext();
     }

     @Override
     public void customize() {
         newScript(CUSTOMIZING)
                 .body.append(
                         format("mkdir -p %s", getRunDir()),
                         format("cp -R %s/dist/{conf,html,logs,sbin} %s", getExpandedInstallDir(), getRunDir()))
                 .execute();

         // Install static content archive, if specified
         String archiveUrl = entity.getConfig(NginxController.STATIC_CONTENT_ARCHIVE_URL);
         if (Strings.isNonBlank(archiveUrl)) {
             getEntity().deploy(archiveUrl);
         }

         customizationCompleted = true;
     }

     @Override
     public boolean isCustomizationCompleted() {
         return customizationCompleted;
     }

     @Override
     public void launch() {
         // TODO if can't be root, and ports > 1024 are in the allowed port range,
         // prefer that; could do this on SshMachineLocation which implements PortSupplier,
         // invoked from PortAttrSensorAndConfigKey, which is invoked from MachineLifecycleTasks.preStartCustom
         Networking.checkPortsValid(MutableMap.of("port", getPort()));

         getEntity().doExtraConfigurationDuringStart();

         // We wait for evidence of running because, using SshCliTool,
         // we saw the ssh session return before the tomcat process was fully running
         // so the process failed to start.
         newScript(MutableMap.of("usePidFile", false), LAUNCHING)
                 .body.append(
                         format("cd %s", getRunDir()),
                         BashCommands.requireExecutable("./sbin/nginx"),
                         sudoBashCIfPrivilegedPort(getPort(), format(
                                 "nohup ./sbin/nginx -p %s/ -c conf/server.conf > %s 2>&1 &", getRunDir(), getLogFileLocation())),
                         format("for i in {1..10}\n" +
                                 "do\n" +
                                 "    test -f %1$s && ps -p `cat %1$s` && exit\n" +
                                 "    sleep 1\n" +
                                 "done\n" +
                                 "echo \"No explicit error launching nginx but couldn't find process by pid; continuing but may subsequently fail\"\n" +
                                 "cat %2$s | tee /dev/stderr",
                                 getPidFile(), getLogFileLocation()))
                 .execute();
     }

     public static String sudoIfPrivilegedPort(int port, String command) {
         return port < 1024 ? BashCommands.sudo(command) : command;
     }

     public static String sudoBashCIfPrivilegedPort(int port, String command) {
         return port < 1024 ? BashCommands.sudo("bash -c '"+command+"'") : command;
     }

     @Override
     public boolean isRunning() {
         return newScript(MutableMap.of("usePidFile", getPidFile()), CHECK_RUNNING).execute() == 0;
     }

     @Override
     public void stop() {
         // Don't `kill -9`, as that doesn't stop the worker processes
         newScript(MutableMap.of("usePidFile", false), STOPPING).
                 body.append(
                         format("cd %s", getRunDir()),
                         format("export PID=`cat %s`", getPidFile()),
                         "test -n \"$PID\" || exit 0",
                         sudoIfPrivilegedPort(getPort(), "kill $PID"))
                 .execute();
     }

     @Override
     public void kill() {
         stop();
     }

     private final ExecController reloadExecutor = new ExecController(
             entity+"->reload",
             new Runnable() {
                 @Override
                 public void run() {
                     reloadImpl();
                 }
             });

     public void reload() {
         // If there are concurrent calls to reload (such that some calls come in when another call is queued), then
         // don't bother doing the subsequent calls. Instead just rely on the currently queued call.
         //
         // Motivation is that calls to nginx.reload were backing up: we ended up executing lots of them in parallel
         // when there were several changes to the nginx conifg that requiring a reload. The problem can be particularly
         // bad because the ssh commands take a second or two - if 10 changes were made to the config in that time, we'd
         // end up executing reload 10 times in parallel.

         reloadExecutor.run();
     }

     private void reloadImpl() {
         // Note that previously, if serviceUp==false then we'd restart nginx.
         // That caused a race on stop()+reload(): nginx could simultaneously be stopping and also reconfiguring
         // (e.g. due to a cluster-resize), the restart() would leave nginx running even after stop() had returned.
         //
         // Now we rely on NginxController always calling update (and thus reload) once it has started. This is
         // done in AbstractController.postActivation().
         //
         // If our blocking check sees that !isRunning() (and if a separate thread is starting it, and subsequently
         // calling waitForEntityStart()), we can guarantee that the start-thread's call to update will happen after
         // this call to reload. So we this can be a no-op, and just rely on that subsequent call to update.

         Lifecycle lifecycle = entity.getAttribute(NginxController.SERVICE_STATE_ACTUAL);
         if (lifecycle==Lifecycle.STOPPING || lifecycle==Lifecycle.STOPPED || !isRunning()) {
             log.debug("Ignoring reload of nginx "+entity+", because service is not running (state "+lifecycle+")");
             return;
         }

         doReloadNow();
     }

     /**
      * Instructs nginx to reload its configuration (without restarting, so don't lose any requests).
      * Can be overridden if necessary, to change the call used for reloading.
      */
     private void doReloadNow() {
         // We use kill -HUP because that is recommended at http://wiki.nginx.org/CommandLine,
         // but there is no noticeable difference (i.e. no impact on #365) compared to:
         //   sudoIfPrivilegedPort(getHttpPort(), format("./sbin/nginx -p %s/ -c conf/server.conf -s reload", getRunDir()))
         //
         // Note that if conf file is invalid, you'll get no stdout/stderr from `kill` but you
         // do from using `nginx ... -s reload` so that can be handy when manually debugging.

         log.debug("reloading nginx by simularing restart (kill -HUP) - {}", entity);
         newScript(RESTARTING)
                 .body.append(
                         format("cd %s", getRunDir()),
                         format("export PID=`cat %s`", getPidFile()),
                         sudoIfPrivilegedPort(getPort(), "kill -HUP $PID"))
                 .execute();
     }

     /**
      * Executes the given task, but only if another thread hasn't executed it for us (where the other thread
      * began executing it after the current caller of {@link #run()} began attempting to do so itself).
      *
      * @author aled
      */
     private static class ExecController {
         private final String summary;
         private final Runnable task;
         private final AtomicLong counter = new AtomicLong();

         ExecController(String summary, Runnable task) {
             this.summary = summary;
             this.task = task;
         }

         void run() {
             long preCount = counter.get();
             synchronized (this) {
                 if (counter.compareAndSet(preCount, preCount+1)) {
                     try {
                         if (log.isDebugEnabled()) log.debug("Executing {}; incremented count to {}", new Object[] {summary, counter});
                         task.run();
                     } catch (Exception e) {
                         if (log.isDebugEnabled()) log.debug("Failed executing {}; reseting count to {} and propagating exception: {}", new Object[] {summary, preCount, e});
                         counter.set(preCount);
                         throw Exceptions.propagate(e);
                     }
                 } else {
                     if (log.isDebugEnabled()) log.debug("Not executing {} because executed by another thread subsequent to us attempting (preCount {}; count {})", new Object[] {summary, preCount, counter});
                 }
             }
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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
	*
	* http://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.apache.brooklyn.entity.proxy.nginx;

	import static java.lang.String.format;

	import java.util.List;
	import java.util.concurrent.atomic.AtomicLong;

	import org.apache.brooklyn.api.entity.drivers.downloads.DownloadResolver;
	import org.apache.brooklyn.api.location.Location;
	import org.apache.brooklyn.api.location.OsDetails;
	import org.apache.brooklyn.api.mgmt.ManagementContext;
	import org.apache.brooklyn.core.entity.Attributes;
	import org.apache.brooklyn.core.entity.EntityInternal;
	import org.apache.brooklyn.core.entity.lifecycle.Lifecycle;
	import org.apache.brooklyn.entity.proxy.AbstractController;
	import org.apache.brooklyn.entity.software.base.AbstractSoftwareProcessSshDriver;
	import org.apache.brooklyn.entity.software.base.lifecycle.ScriptHelper;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;
	import org.apache.brooklyn.location.ssh.SshMachineLocation;
	import org.apache.brooklyn.util.collections.MutableMap;
	import org.apache.brooklyn.util.core.task.DynamicTasks;
	import org.apache.brooklyn.util.core.task.Tasks;
	import org.apache.brooklyn.util.core.task.ssh.SshTasks;
	import org.apache.brooklyn.util.core.task.ssh.SshTasks.OnFailingTask;
	import org.apache.brooklyn.util.exceptions.Exceptions;
	import org.apache.brooklyn.util.net.Networking;
	import org.apache.brooklyn.util.ssh.BashCommands;
	import org.apache.brooklyn.util.stream.Streams;
	import org.apache.brooklyn.util.text.Strings;

	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableMap;
	import com.google.common.collect.Lists;

	/**
	* Start a {@link NginxController} in a {@link Location} accessible over ssh.
	*/
	public class NginxSshDriver extends AbstractSoftwareProcessSshDriver implements NginxDriver {

	// TODO An alternative way of installing nginx is described at:
	// http://sjp.co.nz/posts/building-nginx-for-debian-systems/
	// It's use of `apt-get source nginx` and `apt-get build-dep nginx` makes
	// it look higher level and therefore more appealing.

	public static final Logger log = LoggerFactory.getLogger(NginxSshDriver.class);
	public static final String NGINX_PID_FILE = "logs/nginx.pid";

	private boolean customizationCompleted = false;

	public NginxSshDriver(NginxControllerImpl entity, SshMachineLocation machine) {
	super(entity, machine);

	entity.sensors().set(Attributes.LOG_FILE_LOCATION, getLogFileLocation());
	entity.sensors().set(NginxController.ACCESS_LOG_LOCATION, getAccessLogLocation());
	entity.sensors().set(NginxController.ERROR_LOG_LOCATION, getErrorLogLocation());
	}

	@Override
	public NginxControllerImpl getEntity() {
	return (NginxControllerImpl) super.getEntity();
	}

	public String getLogFileLocation() {
	return format("%s/console", getRunDir());
	}

	public String getAccessLogLocation() {
	String accessLog = entity.getConfig(NginxController.ACCESS_LOG_LOCATION);
	return format("%s/%s", getRunDir(), accessLog);
	}

	public String getErrorLogLocation() {
	String errorLog = entity.getConfig(NginxController.ERROR_LOG_LOCATION);
	return format("%s/%s", getRunDir(), errorLog);
	}

	/** By default Nginx writes the pid of the master process to {@code logs/nginx.pid} */
	@Override
	public String getPidFile() {
	return format("%s/%s", getRunDir(), NGINX_PID_FILE);
	}

	@Deprecated /** @deprecated since 0.7.0 use #getPort */
	public Integer getHttpPort() {
	return getEntity().getPort();
	}

	public Integer getPort() {
	return getEntity().getPort();
	}

	@Override
	public void rebind() {
	customizationCompleted = true;
	}

	@Override
	public void postLaunch() {
	entity.sensors().set(NginxController.PID_FILE, getRunDir() + "/" + AbstractSoftwareProcessSshDriver.PID_FILENAME);
	if (((AbstractController)entity).isSsl()) {
	entity.sensors().set(Attributes.HTTPS_PORT, getPort());
	((EntityInternal)entity).sensors().remove(Attributes.HTTP_PORT);
	} else {
	entity.sensors().set(Attributes.HTTP_PORT, getPort());
	((EntityInternal)entity).sensors().remove(Attributes.HTTPS_PORT);
	}
	super.postLaunch();
	}

	@Override
	public void install() {
	// inessential here, installation will fail later if it needs to sudo (eg if using port 80)
	DynamicTasks.queueIfPossible(SshTasks.dontRequireTtyForSudo(getMachine(), OnFailingTask.WARN_OR_IF_DYNAMIC_FAIL_MARKING_INESSENTIAL)).orSubmitAndBlock();

	List<String> nginxUrls = resolver.getTargets();
	String nginxSaveAs = resolver.getFilename();

	boolean sticky = ((NginxController) entity).isSticky();
	boolean isMac = getMachine().getOsDetails().isMac();

	MutableMap<String, String> installGccPackageFlags = MutableMap.of(
	"onlyifmissing", "gcc",
	"yum", "gcc",
	"apt", "gcc",
	"zypper", "gcc",
	"port", null);
	MutableMap<String, String> installMakePackageFlags = MutableMap.of(
	"onlyifmissing", "make",
	"yum", "make",
	"apt", "make",
	"zypper", "make",
	"port", null);
	MutableMap<String, String> installPackageFlags = MutableMap.of(
	"yum", "openssl-devel pcre-devel",
	"apt", "libssl-dev zlib1g-dev libpcre3-dev",
	"zypper", "libopenssl-devel pcre-devel",
	"port", null);

	String stickyModuleVersion = entity.getConfig(NginxController.STICKY_VERSION);
	DownloadResolver stickyModuleResolver = mgmt().getEntityDownloadsManager().newDownloader(
	this, "stickymodule", ImmutableMap.of("addonversion", stickyModuleVersion));
	List<String> stickyModuleUrls = stickyModuleResolver.getTargets();
	String stickyModuleSaveAs = stickyModuleResolver.getFilename();
	String stickyModuleExpandedInstallDir = String.format("%s/src/%s", getExpandedInstallDir(),
	stickyModuleResolver.getUnpackedDirectoryName("nginx-sticky-module-"+stickyModuleVersion));

	List<String> cmds = Lists.newArrayList();

	cmds.add(BashCommands.ifExecutableElse0("yum", BashCommands.sudo("yum -y install kernel-headers --disableexcludes=all")));
	cmds.add(BashCommands.INSTALL_TAR);
	cmds.add(BashCommands.alternatives(
	BashCommands.ifExecutableElse0("apt-get", BashCommands.installPackage("build-essential")),
	BashCommands.ifExecutableElse0("yum", BashCommands.sudo("yum -y --nogpgcheck groupinstall \"Development Tools\""))));
	cmds.add(BashCommands.installPackage(installGccPackageFlags, "nginx-prerequisites-gcc"));
	cmds.add(BashCommands.installPackage(installMakePackageFlags, "nginx-prerequisites-make"));
	cmds.add(BashCommands.installPackage(installPackageFlags, "nginx-prerequisites"));
	cmds.addAll(BashCommands.commandsToDownloadUrlsAs(nginxUrls, nginxSaveAs));

	String pcreExpandedInstallDirname = "";
	if (isMac) {
	String pcreVersion = entity.getConfig(NginxController.PCRE_VERSION);
	DownloadResolver pcreResolver = mgmt().getEntityDownloadsManager().newDownloader(
	this, "pcre", ImmutableMap.of("addonversion", pcreVersion));
	List<String> pcreUrls = pcreResolver.getTargets();
	String pcreSaveAs = pcreResolver.getFilename();
	pcreExpandedInstallDirname = pcreResolver.getUnpackedDirectoryName("pcre-"+pcreVersion);

	// Install PCRE
	cmds.addAll(BashCommands.commandsToDownloadUrlsAs(pcreUrls, pcreSaveAs));
	cmds.add(format("mkdir -p %s/pcre-dist", getInstallDir()));
	cmds.add(format("tar xvzf %s", pcreSaveAs));
	cmds.add(format("cd %s", pcreExpandedInstallDirname));
	cmds.add(format("./configure --prefix=%s/pcre-dist", getInstallDir()));
	cmds.add("make");
	cmds.add("make install");
	cmds.add("cd ..");
	}

	cmds.add(format("tar xvzf %s", nginxSaveAs));
	cmds.add(format("cd %s", getExpandedInstallDir()));

	if (sticky) {
	// Latest versions of sticky module expand to a different folder than the file name.
	// Extract to folder set by us so we know where the sources are.
	cmds.add(format("mkdir -p %s", stickyModuleExpandedInstallDir));
	cmds.add(format("pushd %s", stickyModuleExpandedInstallDir));
	cmds.addAll(BashCommands.commandsToDownloadUrlsAs(stickyModuleUrls, stickyModuleSaveAs));
	cmds.add(format("tar --strip-component=1 -xvzf %s", stickyModuleSaveAs));
	cmds.add("popd");
	}

	// Note that for OS X, not including space after "-L" because broken in 10.6.8 (but fixed in 10.7.x)
	// see http://trac.nginx.org/nginx/ticket/227
	String withLdOpt = entity.getConfig(NginxController.WITH_LD_OPT);
	if (isMac) withLdOpt = format("-L%s/pcre-dist/lib", getInstallDir()) + (Strings.isBlank(withLdOpt) ? "" : " " + withLdOpt);
	String withCcOpt = entity.getConfig(NginxController.WITH_CC_OPT);

	if (isMac) {
	// TODO Upgrade sticky module as soon as a fix for https://bitbucket.org/nginx-goodies/nginx-sticky-module-ng/issue/16/can-not-compile-on-macosx-yosemite
	// is released and remove this block.
	withCcOpt = (Strings.isBlank(withCcOpt) ? "" : (withCcOpt + " ")) + "-Wno-error";
	}

	StringBuilder configureCommand = new StringBuilder("./configure")
	.append(format(" --prefix=%s/dist", getExpandedInstallDir()))
	.append(" --with-http_ssl_module")
	.append(sticky ? format(" --add-module=%s ", stickyModuleExpandedInstallDir) : "")
	.append(!Strings.isBlank(withLdOpt) ? format(" --with-ld-opt=\"%s\"", withLdOpt) : "")
	.append(!Strings.isBlank(withCcOpt) ? format(" --with-cc-opt=\"%s\"", withCcOpt) : "")
	;
	if (isMac) {
	configureCommand.append(" --with-pcre=")
	.append(getInstallDir()).append("/").append(pcreExpandedInstallDirname);
	}

	cmds.addAll(ImmutableList.of(
	"mkdir -p dist",
	configureCommand.toString(),
	"make install"));

	ScriptHelper script = newScript(INSTALLING)
	.body.append(cmds)
	.header.prepend("set -x")
	.gatherOutput()
	.failOnNonZeroResultCode(false);

	int result = script.execute();

	if (result != 0) {
	String notes = "likely an error building nginx. consult the brooklyn log ssh output for further details.\n"+
	"note that this Brooklyn nginx driver compiles nginx from source. " +
	"it attempts to install common prerequisites but this does not always succeed.\n";
	OsDetails os = getMachine().getOsDetails();
	if (os.isMac()) {
	notes += "deploying to Mac OS X, you will require Xcode and Xcode command-line tools, and on " +
	"some versions the pcre library (e.g. using macports, sudo port install pcre).\n";
	}
	if (os.isWindows()) {
	notes += "this nginx driver is not designed for windows, unless cygwin is installed, and you are patient.\n";
	}
	if (getEntity().getApplication().getClass().getCanonicalName().startsWith("brooklyn.demo.")) {
	// this is maybe naughty ... but since we use nginx in the first demo example,
	// and since it's actually pretty complicated, let's give a little extra hand-holding
	notes +=
	"if debugging this is all a bit much and you just want to run a demo, " +
	"you have two fairly friendly options.\n" +
	"1. you can use a well known cloud, like AWS or Rackspace, where this should run " +
	"in a tried-and-tested Ubuntu or CentOS environment, without any problems " +
	"(and if it does let us know and we'll fix it!).\n"+
	"2. or you can just use the demo without nginx, instead access the appserver instances directly.\n";
	}

	if (!script.getResultStderr().isEmpty()) {
	notes += "\n" + "STDERR\n" + script.getResultStderr()+"\n";
	Streams.logStreamTail(log, "STDERR of problem in "+Tasks.current(), Streams.byteArrayOfString(script.getResultStderr()), 1024);
	}
	if (!script.getResultStdout().isEmpty()) {
	notes += "\n" + "STDOUT\n" + script.getResultStdout()+"\n";
	Streams.logStreamTail(log, "STDOUT of problem in "+Tasks.current(), Streams.byteArrayOfString(script.getResultStdout()), 1024);
	}

	Tasks.setExtraStatusDetails(notes.trim());

	throw new IllegalStateException("Installation of nginx failed (shell returned non-zero result "+result+")");
	}
	}

	private ManagementContext mgmt() {
	return ((EntityInternal) entity).getManagementContext();
	}

	@Override
	public void customize() {
	newScript(CUSTOMIZING)
	.body.append(
	format("mkdir -p %s", getRunDir()),
	format("cp -R %s/dist/{conf,html,logs,sbin} %s", getExpandedInstallDir(), getRunDir()))
	.execute();

	// Install static content archive, if specified
	String archiveUrl = entity.getConfig(NginxController.STATIC_CONTENT_ARCHIVE_URL);
	if (Strings.isNonBlank(archiveUrl)) {
	getEntity().deploy(archiveUrl);
	}

	customizationCompleted = true;
	}

	@Override
	public boolean isCustomizationCompleted() {
	return customizationCompleted;
	}

	@Override
	public void launch() {
	// TODO if can't be root, and ports > 1024 are in the allowed port range,
	// prefer that; could do this on SshMachineLocation which implements PortSupplier,
	// invoked from PortAttrSensorAndConfigKey, which is invoked from MachineLifecycleTasks.preStartCustom
	Networking.checkPortsValid(MutableMap.of("port", getPort()));

	getEntity().doExtraConfigurationDuringStart();

	// We wait for evidence of running because, using SshCliTool,
	// we saw the ssh session return before the tomcat process was fully running
	// so the process failed to start.
	newScript(MutableMap.of("usePidFile", false), LAUNCHING)
	.body.append(
	format("cd %s", getRunDir()),
	BashCommands.requireExecutable("./sbin/nginx"),
	sudoBashCIfPrivilegedPort(getPort(), format(
	"nohup ./sbin/nginx -p %s/ -c conf/server.conf > %s 2>&1 &", getRunDir(), getLogFileLocation())),
	format("for i in {1..10}\n" +
	"do\n" +
	" test -f %1$s && ps -p `cat %1$s` && exit\n" +
	" sleep 1\n" +
	"done\n" +
	"echo \"No explicit error launching nginx but couldn't find process by pid; continuing but may subsequently fail\"\n" +
	"cat %2$s \| tee /dev/stderr",
	getPidFile(), getLogFileLocation()))
	.execute();
	}

	public static String sudoIfPrivilegedPort(int port, String command) {
	return port < 1024 ? BashCommands.sudo(command) : command;
	}

	public static String sudoBashCIfPrivilegedPort(int port, String command) {
	return port < 1024 ? BashCommands.sudo("bash -c '"+command+"'") : command;
	}

	@Override
	public boolean isRunning() {
	return newScript(MutableMap.of("usePidFile", getPidFile()), CHECK_RUNNING).execute() == 0;
	}

	@Override
	public void stop() {
	// Don't `kill -9`, as that doesn't stop the worker processes
	newScript(MutableMap.of("usePidFile", false), STOPPING).
	body.append(
	format("cd %s", getRunDir()),
	format("export PID=`cat %s`", getPidFile()),
	"test -n \"$PID\" \|\| exit 0",
	sudoIfPrivilegedPort(getPort(), "kill $PID"))
	.execute();
	}

	@Override
	public void kill() {
	stop();
	}

	private final ExecController reloadExecutor = new ExecController(
	entity+"->reload",
	new Runnable() {
	@Override
	public void run() {
	reloadImpl();
	}
	});

	public void reload() {
	// If there are concurrent calls to reload (such that some calls come in when another call is queued), then
	// don't bother doing the subsequent calls. Instead just rely on the currently queued call.
	//
	// Motivation is that calls to nginx.reload were backing up: we ended up executing lots of them in parallel
	// when there were several changes to the nginx conifg that requiring a reload. The problem can be particularly
	// bad because the ssh commands take a second or two - if 10 changes were made to the config in that time, we'd
	// end up executing reload 10 times in parallel.

	reloadExecutor.run();
	}

	private void reloadImpl() {
	// Note that previously, if serviceUp==false then we'd restart nginx.
	// That caused a race on stop()+reload(): nginx could simultaneously be stopping and also reconfiguring
	// (e.g. due to a cluster-resize), the restart() would leave nginx running even after stop() had returned.
	//
	// Now we rely on NginxController always calling update (and thus reload) once it has started. This is
	// done in AbstractController.postActivation().
	//
	// If our blocking check sees that !isRunning() (and if a separate thread is starting it, and subsequently
	// calling waitForEntityStart()), we can guarantee that the start-thread's call to update will happen after
	// this call to reload. So we this can be a no-op, and just rely on that subsequent call to update.

	Lifecycle lifecycle = entity.getAttribute(NginxController.SERVICE_STATE_ACTUAL);
	if (lifecycle==Lifecycle.STOPPING \|\| lifecycle==Lifecycle.STOPPED \|\| !isRunning()) {
	log.debug("Ignoring reload of nginx "+entity+", because service is not running (state "+lifecycle+")");
	return;
	}

	doReloadNow();
	}

	/**
	* Instructs nginx to reload its configuration (without restarting, so don't lose any requests).
	* Can be overridden if necessary, to change the call used for reloading.
	*/
	private void doReloadNow() {
	// We use kill -HUP because that is recommended at http://wiki.nginx.org/CommandLine,
	// but there is no noticeable difference (i.e. no impact on #365) compared to:
	// sudoIfPrivilegedPort(getHttpPort(), format("./sbin/nginx -p %s/ -c conf/server.conf -s reload", getRunDir()))
	//
	// Note that if conf file is invalid, you'll get no stdout/stderr from `kill` but you
	// do from using `nginx ... -s reload` so that can be handy when manually debugging.

	log.debug("reloading nginx by simularing restart (kill -HUP) - {}", entity);
	newScript(RESTARTING)
	.body.append(
	format("cd %s", getRunDir()),
	format("export PID=`cat %s`", getPidFile()),
	sudoIfPrivilegedPort(getPort(), "kill -HUP $PID"))
	.execute();
	}

	/**
	* Executes the given task, but only if another thread hasn't executed it for us (where the other thread
	* began executing it after the current caller of {@link #run()} began attempting to do so itself).
	*
	* @author aled
	*/
	private static class ExecController {
	private final String summary;
	private final Runnable task;
	private final AtomicLong counter = new AtomicLong();

	ExecController(String summary, Runnable task) {
	this.summary = summary;
	this.task = task;
	}

	void run() {
	long preCount = counter.get();
	synchronized (this) {
	if (counter.compareAndSet(preCount, preCount+1)) {
	try {
	if (log.isDebugEnabled()) log.debug("Executing {}; incremented count to {}", new Object[] {summary, counter});
	task.run();
	} catch (Exception e) {
	if (log.isDebugEnabled()) log.debug("Failed executing {}; reseting count to {} and propagating exception: {}", new Object[] {summary, preCount, e});
	counter.set(preCount);
	throw Exceptions.propagate(e);
	}
	} else {
	if (log.isDebugEnabled()) log.debug("Not executing {} because executed by another thread subsequent to us attempting (preCount {}; count {})", new Object[] {summary, preCount, counter});
	}
	}
	}
	}
	}