When it comes to deploying your application, simplicity is the biggest advantage. You’ll understand that especially when project evolves and needs some changes in the environment. Packaging up your whole application in one, standalone and self-sufficient JAR seems like a good idea, especially compared to installing and upgrading Tomcat in target environment. In the past I would typically include Tomcat JARs in my web application and write thin command-line runner using Tomcat API. Luckily there is a tomcat7:exec-war maven goal that does just that. It takes your WAR artifact and packages it together with all Tomcat dependencies. At the end it also includes Tomcat7RunnerCli Main-class to manifest.
Curious to try it? Take your existing WAR project and add the following to your pom.xml:
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 | <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.0</version> <executions> <execution> <id>tomcat-run</id> <goals> <goal>exec-war-only</goal> </goals> <phase>package</phase> <configuration> <path>/standalone</path> <enableNaming>false</enableNaming> <finalName>standalone.jar</finalName> <charset>utf-8</charset> </configuration> </execution> </executions></plugin> |
Run mvn package and few seconds later you’ll find shiny standalone.jar in your target directory. Running your web application was never that simple:
1 | $ java -jar target/standalone.jar |
…and you can browse localhost:8080/standalone. Although the documentation of path parameter says (emphasis mine):
The webapp context path to use for the web application being run. The name to store webapp in exec jar. Do not use / just between the two of us, <path>/</path> seems to work after all. It turns out that built in main class is actually a little bit more flexible. For example you can say (I hope it’s self-explanatory):
1 | $ java -jar standalone.jar -httpPort=7070 |
What this runnable JAR does is it first unpacks WAR file inside of it to some directory (.extract by default1) and deploys it to Tomcat – all required Tomcat JARs are also included. Empty standalone.jar (with few KiB WAR inside) weights around 8.5 MiB – not that much if you claim that pushing whole Tomcat with every release alongside your application is wasteful.
Talking about Tomcat JARs, you should wonder how to choose Tomcat version included in this runnable? Unfortunately I couldn’t find any simple option, so we must fall back to explicitly redefining plugin dependencies (version 2.0 has hardcoded 7.0.30 Tomcat). It’s quite boring, but not that complicated and might be useful for future reference:
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 | <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <tomcat7Version>7.0.33</tomcat7Version></properties><build> <plugins> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.0</version> <executions> <execution> <id>tomcat-run</id> <goals> <goal>exec-war-only</goal> </goals> <phase>package</phase> <configuration> <path>/standalone</path> <enableNaming>false</enableNaming> <finalName>standalone.jar</finalName> <charset>utf-8</charset> </configuration> </execution> </executions> <dependencies> <dependency> <groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-core</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-util</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-coyote</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-api</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-jdbc</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-dbcp</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-servlet-api</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-jsp-api</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-jasper</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-jasper-el</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-el-api</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-catalina</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-tribes</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-catalina-ha</artifactId> <version>${tomcat7Version}</version> </dependency> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-annotations-api</artifactId> <version>${tomcat7Version}</version> </dependency> </dependencies> </plugin> </plugins></build> |
In the next article we will learn how to tame these pesky Tomcat internal logs appearing in the terminal (java.util.logging…) In the meantime I discovered and reported MTOMCAT-186 Closing executable JAR does not call ServletContextListener.contextDestroyed() – have look if this is a deal breaker for you.
1 – it might be a good idea to specify different directory using –extractDirectory and clean it before every restart with –resetExtract.
Reference: Standalone web application with executable Tomcat from our JCG partner Tomasz Nurkiewicz at the Java and neighbourhood blog.
Hi, I follow your steps but I received following error:
mac79:kbappsdev2 timba$ java -jar target/standalone.jar
Exception in thread “main” java.lang.NullPointerException
at java.util.StringTokenizer.(StringTokenizer.java:182)
at java.util.StringTokenizer.(StringTokenizer.java:204)
at org.apache.tomcat.maven.runner.Tomcat7Runner.populateWebAppWarPerContext(Tomcat7Runner.java:528)
at org.apache.tomcat.maven.runner.Tomcat7Runner.extract(Tomcat7Runner.java:444)
at org.apache.tomcat.maven.runner.Tomcat7Runner.run(Tomcat7Runner.java:158)
at org.apache.tomcat.maven.runner.Tomcat7RunnerCli.main(Tomcat7RunnerCli.java:204)
Thanks