How do I create my procfile file for heroku?

Question

I'm trying to use Heroku with Java, I have this directory structure and I'm using IntelliJ:

target
  com
    x
     y
      Main.java

in the procfile:

web: java -cp target/classes/;target/dependency/* com.x.y.Main

When I try heroku local web I get " Could not find or load main class com.x.y.Main "

However, it is there. I'm using Windows.

CrazyCoder · Accepted Answer · 2017-02-14T16:03:56.680

3

Java classpath separator is platform dependent, ; for Windows and : for Unix.

If you are trying to run heroku local on Windows, your command will fail with exactly the message you posted. Replacing it with:

web: java -cp target/classes/;target/dependency/* com.x.y.Main

will make it run on Windows.

If you get this error with the app deployed in the cloud (which is Unix), then there is no com.x.y.Main class in the target/classes directory. You can verify that by running heroku run bash followed by ls -lR and checking the directory/files layout on the server.

If you run on Windows ensure to run mvn clean install to compile the sources into target/classes directory.

For Gradle based projects you would need to adjust the classpath since it uses the different layout (build/classes) or the jar file in build/libs, see the guide for the details:

web: java -jar build/libs/myprojectname-1.0-SNAPSHOT.jar

To make it work in cloud and on Windows without changing Procfile every time, create Procfile.windows with web: java -cp target/classes/;target/dependency/* com.x.y.Main and start the app using heroku local web -f Procfile.windows command locally.

edited Feb 14 '17 at 16:03

answered Feb 13 '17 at 20:31

CrazyCoder

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Check my updated post. I updated my procfile but I'm still getting the error – Ali Bdeir Feb 14 '17 at 15:09
@AbAppletic How exactly do you run the app, locally or in cloud, what command is used? Can you provide the list of files in `target/classes`? – CrazyCoder Feb 14 '17 at 15:11
`heroku local web` – Ali Bdeir Feb 14 '17 at 15:13
I don't have a `classes` folder in target – Ali Bdeir Feb 14 '17 at 15:13
That is the case of the problem then, `mvn clean install` should produce the `.class` files there. – CrazyCoder Feb 14 '17 at 15:15
I'm using Gradle, not maven – Ali Bdeir Feb 14 '17 at 15:16
Even when I run `gradlew clean install` no files are created in the `target` directory – Ali Bdeir Feb 14 '17 at 15:32
Gradle probably has different layout, see where the classes are produced and adjust your classpath, in my testing I was using Maven. – CrazyCoder Feb 14 '17 at 15:35
I found it. They're generated in build/classes – Ali Bdeir Feb 14 '17 at 15:39
Great, I've updated the answer to cover all possible cases, hope it works for you now or at least you know where to look. – CrazyCoder Feb 14 '17 at 15:41
So now that I know where they are, what do I do? – Ali Bdeir Feb 14 '17 at 15:41
You need to adjust the classpath to include the classes and dependencies. If you don't have target folder, then your dependencies are also elsewhere. The `-cp` should list everything required to start the app. Adjust the locations depending on the app requirements. – CrazyCoder Feb 14 '17 at 15:44
Is dependecy-cache the dependency folder? – Ali Bdeir Feb 14 '17 at 15:53
it is also in `build` – Ali Bdeir Feb 14 '17 at 15:53
Why don't you just use the final jar with all the dependencies? Does gradle produce one? `web: java -jar /path/to/jar.jar` – CrazyCoder Feb 14 '17 at 15:54
Where would I find that? – Ali Bdeir Feb 14 '17 at 15:55
Should be in `build/libs`, see https://devcenter.heroku.com/articles/deploying-gradle-apps-on-heroku for the sample. – CrazyCoder Feb 14 '17 at 15:56
Error: Unable to access jarfile /build/libs/myprojectname-1.0-SNAPSHOT.jar – Ali Bdeir Feb 14 '17 at 15:59
Do you have `build/libs/myprojectname-1.0-SNAPSHOT.jar` file? What's your `Procfile` now? – CrazyCoder Feb 14 '17 at 16:00
`web: java -jar /build/libs/myprojectname-1.0-SNAPSHOT.jar` is my procfile. I'm sure I have the jar in there – Ali Bdeir Feb 14 '17 at 16:01
You have an extra slash in the start of the path, as you can see from the example, the slash is not used, try this: `web: java -jar build/libs/myprojectname-1.0-SNAPSHOT.jar` – CrazyCoder Feb 14 '17 at 16:02
Now I get this: `no main manifest attribute, in build/libs/myprojectname-1.0-SNAPSHOT.jar` – Ali Bdeir Feb 14 '17 at 16:04
Your jar file doesn't specify the entry point (the main class) in its Manifest. You either need to adjust `build.gradle` to produce the jar with the main class in the manifest or adjust the Procfile to specify the main class. See [this answer](http://stackoverflow.com/a/5474748/104891) for details. – CrazyCoder Feb 14 '17 at 16:08
Exactly what do I add to the build.gradle to produce the jar with the main class in the manifest? – Ali Bdeir Feb 14 '17 at 16:15
I understood what I need to do, but what do i edit? Where is this manifest located? – Ali Bdeir Feb 14 '17 at 16:20
You edit `build.gradle` file and it generates the jar with the manifest for you. – CrazyCoder Feb 14 '17 at 16:21
I understand, but where is the manifest generated so I can edit it? – Ali Bdeir Feb 14 '17 at 16:22
It's generated inside the jar file. `file.jar/META-INF/MANIFEST.MF`. You are not supposed to edit it manually, rather let Gradle generate it. – CrazyCoder Feb 14 '17 at 16:23
If i'm not supposed to edit it manually, then how do I change it? – Ali Bdeir Feb 14 '17 at 16:23
You change `build.gradle` file which in turn affects the Manifest file that is generated by Gradle. – CrazyCoder Feb 14 '17 at 16:24
So what do i change the build.gradle? I can't see anything related to the manifest there – Ali Bdeir Feb 14 '17 at 16:25
It would be much easier to help you if you share your complete project in its current state. As you can see in the [linked answer](http://stackoverflow.com/a/32567525/104891), you add the directive for jar file to specify the main class attribute in the generated jar/manifest. – CrazyCoder Feb 14 '17 at 16:26
I really don't know what you mean by "add the directinve for jar file to specify...". – Ali Bdeir Feb 14 '17 at 16:28
I'll just [refer you to the official Gradle documentation](https://docs.gradle.org/current/userguide/java_plugin.html#sec:jar) so that you study it yourself. Sorry, but I can't explain it any better. – CrazyCoder Feb 14 '17 at 16:30

How do I create my procfile file for heroku?

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