Maven and Spring Boot - non resolvable parent pom - repo.spring.io (Unknown host)

Question

I am trying to build my project but I get this:

Non-resolvable parent POM: Could not transfer artifact org.springframework.boot:spring-boot-starter-parent:pom:1.3.0.M3 from/to spring-snapshots (http://repo.spring.io/snapshot): repo.spring.io and 'parent.relativePath' points at no local POM @ line 16, column 10: Unknown host repo.spring.io -> [Help 2]

Here is how I specify the parent of my pom.xml:

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.0.M3</version>
        <relativePath></relativePath>
    </parent>

The is empty so that it forces maven to look for the parent in the remote repository. However, it says that repo.spring.io is an unknown host.

Here is how I define the repositories in my pom.xml:

<repositories>
        <repository>
            <id>spring-snapshots</id>
            <url>http://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>spring-milestones</id>
            <url>http://repo.spring.io/milestone</url>
        </repository>
    </repositories>

<pluginRepositories>
    <pluginRepository>
        <id>spring-snapshots</id>
        <url>http://repo.spring.io/snapshot</url>
    </pluginRepository>
    <pluginRepository>
        <id>spring-milestones</id>
        <url>http://repo.spring.io/milestone</url>
    </pluginRepository>
</pluginRepositories>

Any ideas?

Answer 1

Obviously it's a problem with your internet connection. Check, if you can reach http://repo.spring.io with your browser. If yes, check if you need to configure a proxy server. If no, you should contact your internet provider.

Here is the documentation, how you configure a proxy server for Maven: https://maven.apache.org/guides/mini/guide-proxies.html

Answer 2

The issue is with your project which is not able to complete maven build. Steps to follow :

1. Right Click Application and RunAs maven install.
2. If you get any error while reaching the repos online try giving the proxies in settings.xml under your .m2 directory.Check this link for setting proxies for maven build.
3. Once done , try doing a Update Project by Right Click Project , Maven->Update Maven Project and select codebase and do check the Force Update of Snapshot/Release check box.

This will update your maven build and will surely remove your errors with pom.xml

Answer 3

If you're using docker-machine (docker on Windows or OSX).

Currently docker-machine has a bug that it loses internet connection if you switch between wifi networks or wifi and cable.

Make sure you restart your docker-machine

usually: docker-machine restart default

Answer 4

Rigth button on your project -> Maven -> Update

Answer 5

Project->maven->Update Project->tick all checkboxes expect offline and error is solved soon.

Answer 6

it's a problem with your internet connection. Might be there are some restriction thats why you are unable to reach http://repo.spring.io with your browser.

Answer 7

In my case the problem was with the java version mismatch of pom.xml (java 1.8) and environment variables JAVA_HOME/JDK_HOME (java 1.7). After pointing environment variables JAVA_HOME & JDK_HOME to Java 1.8, the issue got resolved.