Four things Heroku stumbled upon when deploying a web app created in Java with GitHub
Trigger I had a web application I created on GitHub, "I want to publish it in a moving state!" That was the reason why I started to feel that.
Various googles "It looks like Heroku can be used." I found out that, so I decided to deploy it after studying.
Source: https://github.com/ShandyGaffLover/sample001
Premise
・ Heroku for the first time
・ Experienced Java, Git, Maven
・ GitHub account created
What I did
Create Heroku account ⇒ GitHub integration
I was able to do it relatively smoothly while googled.
The articles I referred to are as follows: I tried Heroku, which can publish web applications for free --Qiita https://qiita.com/fkooo/items/0365b50d4534a236dcb2
Heroku Usage Memo (Java)-Qiita https://qiita.com/opengl-8080/items/9dc9243c4e68cd0674f8
Stumble
① "I don't know the language of the app" and it doesn't build
Phenomenon
After selecting the repository to be linked and the branch to deploy, when the "Deploy Branch" button was pressed, "No default language could be detected for this app." Was displayed.
Phenomenon After selecting the repository to be linked and the branch to deploy, when the "Deploy Branch" button was pressed, "No default language could be detected for this app." Was displayed.
Cause
Because Buildpack is not set.
Correspondence
Click "Add build pack" from the bottom of the "Settings" tab page, and select "heroku / java" to add it.
Result
When I pressed the "Deploy Branch" button again, I still got a build error as shown below.
Result When I pressed the "Deploy Branch" button again, I still got a build error as shown below.
② "pom.xml cannot be found" and it is not built
Phenomenon
After responding to ①, when the "Deploy Branch" button was pressed again, "Could not find a pom.xml file! Please check that it exists and is committed to Git." Was displayed.
Cause
Because pom.xml does not exist directly under the repository.
Cause Because pom.xml does not exist directly under the repository.
I originally created the sample001 project under the training repository, so pom.xml was in the location training / sample001 / pom.xml. Apparently you can't deploy to Heroku at this location.
- There was a similar example. Heroku: I'm addicted to Buildpack errors-Qiita https://qiita.com/arekore0/items/eae550bdbcc78eeac082
Correspondence
I created a new repository sample001, placed pom.xml directly under it, and moved the source.
Result
When I pressed the "Deploy Branch" button again, the build was successful as shown below. You did it!
I thought ... for a moment
When I access the URL, I get an Application Error ...
③ Web process is not running after deployment
Phenomenon
After successful deployment, click the "View" button to access the application URL, and a screen notifying Application Error will be displayed.
If you refer to the log, it will be displayed as follows.
2018-12-06T07:09:36.166348+00:00 heroku[router]: at=error code=H14 desc="No web processes running"
Cause
The web application is not running without the Procfile being created. [^ 1]
[^ 1]: I'm not so sure if this Japanese is technically correct. Anyone who is familiar with the relationship between Procfile and deployed assets, would appreciate it if you could point out any mistakes.
Correspondence
Refer to the following, (1) Create a Procfile, and (2) Add webapp-runner to the plugin of pom.xml.
Deploying Tomcat-based Java Web Applications with Webapp Runner | Heroku Dev Center
https://devcenter.heroku.com/articles/java-webapp-runner#deploy-your-application-to-heroku
Result
2018-12-06T07:09:36.166348+00:00 heroku[router]: at=error code=H14 desc="No web processes running"
Cause
The web application is not running without the Procfile being created. [^ 1]
[^ 1]: I'm not so sure if this Japanese is technically correct. Anyone who is familiar with the relationship between Procfile and deployed assets, would appreciate it if you could point out any mistakes.
Correspondence
Refer to the following, (1) Create a Procfile, and (2) Add webapp-runner to the plugin of pom.xml.
Deploying Tomcat-based Java Web Applications with Webapp Runner | Heroku Dev Center
https://devcenter.heroku.com/articles/java-webapp-runner#deploy-your-application-to-heroku
Result
Result 
The Application Error is still displayed. Yeah ... why ...
④ "war file does not exist" is displayed in the log
Phenomenon
After responding to (3), if the deployment is successful and the "View" button is pressed to access the application URL, a screen notifying Application Error will be displayed.
If you refer to the log, it will be displayed as follows.
2018-12-06T10:51:25.163976+00:00 app[web.1]: The specified path "target/*.war" does not exist.
2018-12-06T10:51:25.163976+00:00 app[web.1]: The specified path "target/*.war" does not exist.
I was confused because I didn't know the cause at first [^ 2], but in most cases, the cause is often poor.
Cause
Because packaging of pom.xml was not described.
Correspondence
Specify "war" in packaging of pom.xml.
Result
Successful deployment!
Summary
When using Heroku for the first time, you should be aware of the following.
(1) Buildpack settings are required.
(2) For Java, it is necessary to place pom.xml directly under the repository.
③Procfile is required.
Result
Successful deployment!
Summary
When using Heroku for the first time, you should be aware of the following.
(1) Buildpack settings are required.
(2) For Java, it is necessary to place pom.xml directly under the repository.
③Procfile is required.
I was afraid that I forgot to specify "war" in
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