Can anyone give a good example of using org.apache.maven.cli.MavenCli programmatically?

Question

I'm trying to create an intelliJ plugin that needs to execute maven targets on the current project. All the talk in the intertubes recommends using the MavenEmbedder. Good luck with that. The 2.0.4 version isn't well supported and there are no references for how to use it.

I gave it a whirl and ran into a wall where the embedder had not been initialized with all the fields it needs. Reflective private member injection? Awesome! Why would anyone need an obvious way to initialize an object?

It seems a few people are using a 2.1 version with some success. I have been unable to find that in a jar or even sources.

I went and checked out the 3.0 version of the embedder project: http://maven.apache.org/ref/3.0-beta-3/maven-embedder/ It does away with the MavenEmbedder object all together and seems to only support access through the main or doMain methods on MavenCli. Has anyone used these methods and can give some advice?

Answer 1

Yeah, the's not much in the way of documentation of MavenCli. The API is significatly simpler but i'd still like some examples. Here's one that works...

MavenCli cli = new MavenCli();
int result = cli.doMain(new String[]{"compile"},
        "/home/aioffe/workspace/MiscMaven",
        System.out, System.out);
System.out.println("result: " + result);

It takes a dir and runs the 'compile' phase...

Answer 2

Working maven configuration for maven 3.1.1

Dependencies

<dependencies>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-embedder</artifactId>
        <version>3.1.1</version>
    </dependency>
    <dependency>
        <groupId>org.eclipse.aether</groupId>
        <artifactId>aether-connector-wagon</artifactId>
        <version>0.9.0.M2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.wagon</groupId>
        <artifactId>wagon-http-lightweight</artifactId>
        <version>2.5</version>
    </dependency>
</dependencies>

Code

MavenCli cli = new MavenCli();

cli.doMain(new String[]{"clean", "compile"}, "project_dir", System.out, System.out);

Answer 3

The dependency matrix information for provided scopes and dynamically acquired components can be a bit confusing. It was for me, since it appeared to me that I got all the required items by direct or transitive dependency, but then remote resolution didn't work.

I wanted to jump to Maven 3.3.3 (latest as of 2015-05-25). I got it working without the sisu errors that presented when I tried to optimistically update to current versions of things specified here (and elsewhere). This is a project with a tag that worked with the example specified as of today using JDK8.

https://github.com/mykelalvis/test-maven-embedder/tree/20150525-working

Relevant deps (SLF4J is just so I can see the logs)

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.5</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-embedder</artifactId>
        <version>3.3.3</version>
    </dependency>
    <dependency>
        <groupId>org.eclipse.aether</groupId>
        <artifactId>aether-connector-basic</artifactId>
        <version>1.0.2.v20150114</version>
    </dependency>
    <dependency>
        <groupId>org.eclipse.aether</groupId>
        <artifactId>aether-transport-wagon</artifactId>
        <version>1.0.2.v20150114</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.wagon</groupId>
        <artifactId>wagon-http</artifactId>
        <version>2.9</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.wagon</groupId>
        <artifactId>wagon-provider-api</artifactId>
        <version>2.9</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.wagon</groupId>
        <artifactId>wagon-http-lightweight</artifactId>
        <version>2.9</version>
    </dependency>   

Running this is:

rm -r ~/.m2/repository/org/apache/maven/plugins/maven-clean-plugin/
mvn exec:java

Probably should have made it a unit test of some sort.

If someone has a superior solution for embedded Maven 3.3.3 (i.e. came up with a smaller or more range-oriented set of required dependencies), please post them.

Answer 4

to build on the comment from @StevePerkins, and using maven version 3.1.0,

I had to exclude the transitive dependency from aether-connector-wagon to wagon-provider-api to get it working.

pom.xml:

(...)
<dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-embedder</artifactId>
    <version>3.1.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.eclipse.aether</groupId>
    <artifactId>aether-connector-wagon</artifactId>
    <version>0.9.0.M2</version>
    <scope>test</scope>
    <exclusions>
        <exclusion>
            <groupId>org.apache.maven.wagon</groupId>
            <artifactId>wagon-provider-api</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.apache.maven.wagon</groupId>
    <artifactId>wagon-http</artifactId>
    <version>2.5</version>
    <scope>test</scope>
</dependency>
(...)

and here is a java example:

(...)
MavenCli cli = new MavenCli();

ByteArrayOutputStream baosOut = new ByteArrayOutputStream();
ByteArrayOutputStream baosErr = new ByteArrayOutputStream();

PrintStream out = new PrintStream(baosOut, true);
PrintStream err = new PrintStream(baosErr, true);

cli.doMain( new String[] { "clean" }, new File("."), out, err );

String stdout = baosOut.toString("UTF-8");
String stderr = baosErr.toString("UTF-8");
(...)

full example here

Answer 5

There is a dependency matrix for each version of maven-embedder, e.g. for 3.2.5: http://maven.apache.org/ref/3.2.5/maven-embedder/dependencies.html

Based on that I had to use org.apache.maven:maven-embedder:jar:3.2.5, org.apache.maven:maven-aether-provider:jar:3.2.5, and org.apache.maven.wagon:wagon-provider-api:jar:2.8.

It also fixes dependency on very old Guava library, since this version uses 18.0.