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Adding Version Details on MANIFEST.MF via Jenkins

· DevOps Zone

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Article Purpose:

The following article will suggest a solution for adding custom information to your web application using manifest.mf file and expose that information in API.

The necessity for this solution came to solve "blindness" in deployment. in simpler words,

I want to know what war i deployed, what build version it has and more useful information i might need.

Since i exposed the information via API, this could function as application "health-check", so this is a nice little addition for the solution.

Techs:

  • war (your web application)
  • mvn - build tool
  • maven-war-plugin
  • Jenkins job

Step 1 - Adding maven war plugin

First you should add the maven war plugin to your pom.xml.

In the <manifestEntries> tag you should add the custom information you need. in case you want to use the default information the plugin gives you out of the box, just mark the value of <addDefaultImplementationEntries> as true.

In the following example you can see i added fields like buildVersion, build time and so on. This build tool is going to provide this data, in this case jenkins.

<build>
    <plugins>
 <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <configuration>
   <manifest>
    <addDefaultImplementationEntries>false</addDefaultImplementationEntries>
   </manifest>
   <archive>
    <manifestEntries>
     <Major-Version>${project.version}</Major-Version>
     <Build-Version>${build.number}</Build-Version>
     <Build-Time>${maven.build.timestamp}</Build-Time>
     <Build-Host>${agent.name}</Build-Host>
     <Build-User>${user.name}</Build-User>
    </manifestEntries>
   </archive>
  </configuration>
 </plugin>
   </plugins>
 <finalName>${[yourWarName].war.finalName}</finalName>
</build>

Step 2 - Define maven variables

The properties you want to add should be provided from "out side", you should add variables in your pom so Jenkins assign the values there.

In the following example below, you can see the build.number variable i defined in the previous step.

<build.number>SNAPSHOT</build.number>

Step 3 - Adding maven goals to your Jenkins job definitions

Jenkins has available environment variables you can pass to the maven goal,
such as BUILD_NUMBER, BUILD_ID and so on.
assign the Jenkins variable to the maven variable in the build step.
when Jenkins is going to build the code, it going to sign the manifest,mf file with the custom information we wanted.


Step 4 - Exposing the information of war

We did all this hard work for one purpose. so we will have this information available in deployment stage.

you should expose via API this information. in this example i used Spring MVC controller, and mapped the data to json format but you can have your pick.

  package your.package;

  @Controller
  @RequestMapping(value = "/version", produces = MediaType.APPLICATION_JSON_VALUE)
    public class VersionController {

 @Autowired
 ApplicationContext applicationContext;
 
 @RequestMapping(method = RequestMethod.GET)
 @ResponseBody
 public JSONObject getVersion() {
  JSONObject result = new JSONObject();
  Resource resource = applicationContext.getResource("/META-INF/MANIFEST.MF");
  
  try {
   Manifest manifest = new Manifest(resource.getInputStream());
   if (manifest != null){
    Attributes mainAttributes = manifest.getMainAttributes();
    if(mainAttributes != null){
     for (Object key : mainAttributes.keySet()) {
      result.put(key, mainAttributes.get(key));
     }
    }
   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
     return result;

 }

}
       

Step 5 - Enjoy :)

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