[Rejected by License Issue]add cluster nacos support

[litian33]

Please answer these questions before submitting pull request

• Why submit this pull request?
• Bug fix
• [ x ] New feature provided
• Improve performance

---

New feature or improvement

• Support for discovering cluster nodes through nacos.

This feature depends on alibaba/nacos (https://github.com/alibaba/nacos).

The LICENSE is APL 2.0 (https://github.com/alibaba/nacos/blob/master/LICENSE).

[wu-sheng]

This feature depends on alibaba/nacos (https://github.com/alibaba/nacos).

Does nacos-client depend on other 3rd-party libs? I assume YES. And what are they?

[litian33]

This feature depends on alibaba/nacos (https://github.com/alibaba/nacos).

Does nacos-client depend on other 3rd-party libs? I assume YES. And what are they?

This is the list of 3rd-party libs depended by nacos-client:

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-slf4j-impl</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>nacos-common</artifactId>
        </dependency>

        <dependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>nacos-api</artifactId>
        </dependency>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
        </dependency>

        <dependency>
            <artifactId>commons-codec</artifactId>
            <groupId>commons-codec</groupId>
        </dependency>

        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-lgpl</artifactId>
        </dependency>
        <dependency>
            <groupId>net.jcip</groupId>
            <artifactId>jcip-annotations</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>com.github.spotbugs</groupId>
            <artifactId>spotbugs-annotations</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient</artifactId>
            <version>0.5.0</version>
        </dependency>

The license info:

component	license
slf4j-api	MIT License
junit	EPL 1.0
spotbugs-annotations	LGPL
jackson-mapper-lgpl	LGPL 2.1
logback	EPL 1.0 & LGPL 2.1

The other compotents license is APL 2.0.

[wu-sheng]

The licenses look like good, but what does the optional mean? Does the end user need that or not?

The right list would be the jars added in skywalking dist tar. Could you cross check your new dist with skywalking's master dist?

[JaredTan95]

Wow, It's a cool feature for skywalking cluster.

[litian33]

The licenses look like good, but what does the optional mean? Does the end user need that or not?

The right list would be the jars added in skywalking dist tar. Could you cross check your new dist with skywalking's master dist?

'optional' means it will not be included in the dist jars.

[coveralls]

Coverage remained the same at 13.898% when pulling 29c6fae on litian33:cluster-nacos-support into 16aca37 on apache:master.

[wu-sheng]

@JaredTan95 Could you test and verify this PR?

@litian33 You need to follow this LICENSE file, https://github.com/apache/incubator-skywalking/blob/master/apm-dist/release-docs/LICENSE#L204

1. add license descriptions of your new jars(in dist lib)
2. If LICENSE is not Apache 2.0, you need to copy the license file to license folder
3. If LICENSE is Apache 2.0, and it includes NOTICE file in same folder, you need to copy the contents into our dist NOTICE

This is the legal way :) So you must follow. Also, after you have done, please provide a list in here to help us recheck these dependencies.

[peng-yongsheng]

| spotbugs-annotations | LGPL |
| jackson-mapper-lgpl | LGPL 2.1 |

@wu-sheng GNU LGPL 2, 2.1, 3 may NOT be included within Apache products.

[wu-sheng]

GNU LGPL 2, 2.1, 3 may NOT be included within Apache products.

@peng-yongsheng Oh, sorry I miss one. Dependency jackson-mapper-lgpl is not optional. Thank you for pointing this out.

@litian33 We can't accept this PR because it breaks the Apache foundation requirements. You can use them, but in Apache release and source code host, we can't. If you want to contribute this, I will recommend you open source in another repo, and release there, we could provide a document link to there. In that repo, you could do release by following your own wish and provide the document to guide user to use.

If you want to make this in Apache repo, then all GPL/LGPC must be removed, please read catalog-x

[litian33]

OK. I will matain the fork myself.

[wu-sheng]

@litian33 I suggest you do something like https://github.com/SkyAPM/java-plugin-extensions . You deploy the plugin based on our release API, then release by yourself.

People could download from your page, and copy them into skywalking lib folder to active it.

The fork is unsearchable in GitHub. So, a new repo is a better choice from my perspective.

[wu-sheng]

@litian33 After you released, we are welcome to accept your PR to submit documents in cluster management section, which could include a link to your repo or release page.

We are highly appreciated your contributions and extension.

[wu-sheng]

@litian33 Nacos team is responding. You could follow the issue I just raised.

[wu-sheng]

@litian33 I have got contact with Nacos team, they are working on removing the LGPL libs. So, could you try to update to next release, and submit a new PR again?

[wu-sheng]

@litian33 Could you try to use the latest Nacos release to submit a new PR and list the new dependencies there?