![]() Version: 9.4.30.v20200611 |
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Table of Contents
The start.jar bootstrap manages the startup of standalone Jetty.
It is responsible for:
start.jar bootstrap builds a classpath for all the required Jetty features and their dependencies.
It builds the classpath using either the --lib option to start.jar to add an individual classpath entry, or with the --module option that includes all the libs and their dependencies for a module (a named Jetty feature).start.jar.start.jar mechanism resolves canonical locations for the ${jetty.home} and the ${jetty.base} directories.
The ${jetty.home} directory is the location of the standard distribution of Jetty.
The ${jetty.base} directory is the location of the local server customization and configurations.
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If you want to modify the Jetty distribution, base and home can be the same directory.
Separating the base and home directories allows the distribution to remain unmodified, with all customizations in the base directory, and thus simplifies subsequent server version upgrades.start.jar mechanism allows you to set parameters on the command line or in properties files.To achieve these start up mechanisms, the start.jar uses:
start.jar mechanism uses the contents of the ${jetty.base}/start.ini and ${jetty.base}/start.d/*.ini files with each line equivalent to a start.jar command line argument.
This means that either a global start.ini file or multiple start.d/feature.ini files control the configuration of the server.It is important to chose either ${jetty.base}/start.ini or ${jetty.base}/start.d/*.ini to manage configuration.
Using both is not recommended and can lead to issues with your server.
start.jar mechanism allows you to create modules.
A module is defined in a modules/*.mod file, including the libraries, dependencies, XML, and template INI files for a Jetty feature.
Thus you can use a single --module=name command line option as the equivalent of specifying --lib=location, feature.xml or name=value arguments for a feature and all its dependencies.
Modules also use their dependencies to control the ordering of libraries and XML files.
There are several module files included with the Jetty distribution that cover the most common server features, such as HTTP, HTTPS, SSL, Logging, Annotations…etc.
These module files should only be edited if you are making structural changes to the way the feature will perform.
For more information, refer to the section on managing startup modules later in this chapter.The simplest way to start Jetty is via the start.jar mechanism using the following Java command line:
[user]$ cd jetty-distribution-9.4.30.v20200611 [jetty-distribution-9.4.30.v20200611]$ java -jar start.jar --module=http jetty.http.port=8080
This command uses the start.jar mechanism to bootstrap the classpath, properties, and XML files with the metadata obtained from the http module.
Specifically the http module is defined in the ${jetty.home}/modules/http.mod file, and includes the following:
[jetty-distribution-9.4.30.v20200611]$ cat modules/http.mod [depend] server [xml] etc/jetty-http.xml [ini-template] jetty.http.port=8080 http.timeout=30000
The http module declares that http depends on the server module, uses the jetty-http.xml file, and can be parameterized with jetty.http.port and http.timeout parameters.
The INI-template section is not actually used by the command above, so the jetty.http.port must still be defined on the command line.
Following the server dependency, the ${jetty.home}/modules/server.mod file includes:
[jetty-distribution-9.4.30.v20200611]$ cat modules/server.mod
[lib]
lib/servlet-api-3.1.jar
lib/jetty-http-${jetty.version}.jar
lib/jetty-server-${jetty.version}.jar
lib/jetty-xml-${jetty.version}.jar
lib/jetty-util-${jetty.version}.jar
lib/jetty-io-${jetty.version}.jar
[xml]
etc/jetty.xml
[ini-template]
threads.min=10
threads.max=200The server module declares the libraries the server needs and to use jetty.xml file.
The combined metadata of the http and server modules results in start.jar generating the effective Java command line required to start Jetty.
Another way to see this is by asking Jetty what its configuration looks like by appending --list-config to the command line:
[jetty-distribution-9.4.30.v20200611]$ java -jar start.jar --module=http jetty.http.port=9099 --list-config
Java Environment:
-----------------
java.home=/user/lib/jvm/jdk-7u21-x64/jre
java.vm.vendor=Oracle Corporation
java.vm.version=23.25-b01
java.vm.name=Java HotSpot(TM) 64-Bit Server VM
java.vm.info=mixed mode
java.runtime.name=Java(TM) SE Runtime Environment
java.runtime.version=1.7.0_25-b15
java.io.tmpdir=/tmp
Jetty Environment:
-----------------
jetty.home=/opt/jetty/jetty-distribution-9.4.30.v20200611
jetty.base=/opt/jetty/jetty-distribution-9.4.30.v20200611
jetty.version=9.4.30.v20200611
JVM Arguments:
--------------
(no jvm args specified)
System Properties:
------------------
jetty.home = /opt/jetty/jetty-distribution-9.4.30.v20200611
jetty.base = /opt/jetty/jetty-distribution-9.4.30.v20200611
Properties:
-----------
jetty.http.port = 9099
Jetty Server Classpath:
-----------------------
Version Information on 7 entries in the classpath.
Note: order presented here is how they would appear on the classpath.
changes to the --module=name command line options will be reflected here.
0: 3.1.0 | ${jetty.home}/lib/servlet-api-3.1.jar
1: 3.1.RC0 | ${jetty.home}/lib/jetty-schemas-3.1.jar
2: 9.4.30.v20200611 | ${jetty.home}/lib/jetty-http-9.4.30.v20200611.jar
3: 9.4.30.v20200611 | ${jetty.home}/lib/jetty-server-9.4.30.v20200611.jar
4: 9.4.30.v20200611 | ${jetty.home}/lib/jetty-xml-9.4.30.v20200611.jar
5: 9.4.30.v20200611 | ${jetty.home}/lib/jetty-util-9.4.30.v20200611.jar
6: 9.4.30.v20200611 | ${jetty.home}/lib/jetty-io-9.4.30.v20200611.jar
Jetty Active XMLs:
------------------
${jetty.home}/etc/jetty.xml
${jetty.home}/etc/jetty-http.xmlThis represents the entirety of the configuration that is applied to start Jetty.
If you don’t want to use the start.jar bootstrap, you can start Jetty using a traditional Java command line.
The following is the equivalent Java command line for what the start.jar bootstrap above performs.
[user]$ cd jetty-distribution-9.4.30.v20200611
[jetty-distribution-9.4.30.v20200611]$ echo jetty.http.port=8080 > /tmp/jetty.properties
[jetty-distribution-9.4.30.v20200611]$ export JETTY_HOME=`pwd`
[jetty-distribution-9.4.30.v20200611]$ export JETTY_BASE=`pwd`
[jetty-distribution-9.4.30.v20200611]$ export JETTY_VERSION="${project.version}"
[jetty-distribution-9.4.30.v20200611]$ java -Djetty.home=$JETTY_HOME \
-Djetty.base=$JETTY_BASE \
-cp \
$JETTY_HOME/lib/servlet-api-3.1.jar\
:$JETTY_HOME/lib/jetty-schemas-3.1.jar\
:$JETTY_HOME/lib/jetty-http-$JETTY_VERSION.jar\
:$JETTY_HOME/lib/jetty-server-$JETTY_VERSION.jar \
:$JETTY_HOME/lib/jetty-xml-$JETTY_VERSION.jar\
:$JETTY_HOME/lib/jetty-util-$JETTY_VERSION.jar\
:$JETTY_HOME/lib/jetty-io-$JETTY_VERSION.jar\
org.eclipse.jetty.xml.XmlConfiguration \
/tmp/jetty.properties \
$JETTY_HOME/etc/jetty.xml \
$JETTY_HOME/etc/jetty-http.xmlThe Java command line sets up the classpath with the core Jetty jars and the servlet API, executes the XmlConfiguration class and passes it some XML files that define the server and an HTTP connector running on the port defined in the jetty.properties file.
You can further simplify the startup of this server by using the INI template defined by the modules to create a start.ini file with the command:
[user]$ cd jetty-distribution-9.4.30.v20200611
[jetty-distribution-9.4.30.v20200611]$ mkdir example-base
[example-base]$ cd example-base
[example-base]$ ls -la
total 8
drwxrwxr-x 2 user webgroup 4096 Oct 4 11:49 ./
drwxrwxr-x 12 user webgroup 4096 Oct 4 11:49 ../
[example-base]$ java -jar $JETTY_HOME/start.jar --add-to-start=http
WARNING: http initialised in ${jetty.base}/start.ini (appended)
WARNING: http enabled in ${jetty.base}/start.ini
WARNING: server initialised in ${jetty.base}/start.ini (appended)
WARNING: server enabled in ${jetty.base}/start.ini
[example-base]$ ls -la
total 12
drwxrwxr-x 2 user webgroup 4096 Oct 4 11:55 ./
drwxrwxr-x 12 user webgroup 4096 Oct 4 11:49 ../
-rw-rw-r-- 1 user webgroup 250 Oct 4 11:55 start.iniOnce complete, you can edit the start.ini file to modify any parameters and you can run the server with the simple command:
[example-base]$ java -jar $JETTY_HOME/start.jar