Repository: societe-generale/github-crawler (kotlin)

Issue:
Running a simple configuration to crawl a Github organisation seems to fail
## Summary

I am not able to run and test the github-crawler without showing me always the message:

`Factory method 'remoteGitHub' threw exception; nested exception is java.lang.NullPointerException: name`

## Type of Issue
It is a : 
 - [ ] bug
 - [ ] request
 - [X] question regarding the documentation


## Motivation
I really would like to test your github-crawler, but it seems that I am doing something wrong in the `application.yml` file.
For testing your application, I am trying to crawl the **python** organisation:

https://github.com/python/

(Later I would like to focus on specific repositories, so not directly on organisation, but for simplicity reasons I am asking right now for an organisation).

This is the `application.yml` conifugration file I am using:

```
crawler:
    
    source-control:    
        # since v2.0.0, we need to mention the source control type. defaults to GitHub, but other options are possible
        # as defined in https://github.com/societe-generale/github-crawler/blob/master/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/GithubConfig.kt
        type: "GITHUB"
        # the base GitHub URL for your Github enterprise instance to crawl
        # or if it's github.com...
        gitHub.url: https://api.github.com
        # url: https://my.githubEnterprise/api/v3
        apiToken: "YOUR_TOKEN"
        # the name of the GitHub organization to crawl. To fetch the repositories, the crawler will hit 
        # https://${gitHub.url}/api/v3/orgs/${organizationName}/repos
        organizationName: python
        # default is false - API URL is slightly different depending on whether you're crawling an organization (most common case) or a user's repositories
        crawlUsersRepoInsteadOfOrgasRepos: false
     
     
    #### From here is the same configuration as written in README.MD, but even without the default configuration below it also seems to fail

```

For creating the token, I generated a **Personal Access Token** as described here in the offical guide from GitHub:

https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/creating-a-personal-access-token

For testing I gave my Personal Access Token full-access, just to make sure it is not because of the given rights of the token itself.


For crawling itself I am using this version:
https://repo1.maven.org/maven2/com/societegenerale/github-crawler/github-crawler-starter/2.0.1/

And this is how I am running the jar file:
`java -jar github-crawler-starter-2.0.1-exec.jar --spring.config.location=./`



## Current Behavior

The current provided `application.yml` seems to be fine, since I am able to run the application, however if fails with this error message:

`org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'gitHubCrawlerApplication': Unsatisfied dependency expressed through field 'crawler'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'crawler' defined in class path resource [com/societegenerale/githubcrawler/config/GitHubCrawlerAutoConfiguration.class]: Unsatisfied dependency expressed through method 'crawler' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'remoteGitHub' defined in class path resource [com/societegenerale/githubcrawler/config/GitHubConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.societegenerale.githubcrawler.remote.RemoteSourceControl]: Factory method 'remoteGitHub' threw exception; nested exception is java.lang.NullPointerException: name`


## Expected Behavior

I am expecting that the github-crawler application is doing the crawler, but for right now it is not able to do it so.



I am definitely doing something wrong, but I cannot figure out what it is.
Could you please help me on that, since I cannot figure out from the documentation what else I am missing.

If you need more information, please do not hesitate to contact me!

Pull request description:
fixes #105

Patch:
diff --git a/README.md b/README.md
index 0993d26..1028fa2 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ Following a simple configuration, it will use Github API starting from a given o
 
 You can easily exclude repositories from the analysis, configure the files and patterns you're interested in. If you have several types of repositories (front-end, back-end, config repositories for instance), you can have separate configuration files so that the information retrieved is relevant to each scope of analysis.
 
-Several output types are available in [this package](./github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/output/) :
+Several output types are available in [this package](./tree/master/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/output) :
 - console is the default and will be used if no output is configured
 - a simple "raw" file output
 - HTTP output, which enables you to POST the results to an endpoint like ElasticSearch, for easy analysis in Kibana
@@ -59,12 +59,11 @@ crawler:
         # since v2.0.0, we need to mention the source control type. defaults to GitHub, but other options are possible
         # as defined in https://github.com/societe-generale/github-crawler/blob/master/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/GithubConfig.kt
         type: "GITHUB"
-        # the base GitHub URL for your Github enterprise instance to crawl
-        # or if it's github.com...
-        # gitHub.url: https://api.github.com
+        # the base GitHub URL for your Github enterprise or on prem GitLab instance to crawl. 
+        # defaults to public URL for GitHub and Azure Devops if not provided in config. 
         url: https://my.githubEnterprise/api/v3
         apiToken: "YOUR_TOKEN"
-        # the name of the GitHub organization to crawl. To fetch the repositories, the crawler will hit 
+        # the name of the GitHub organization (or equivalent for other systems) to crawl. To fetch the repositories, the crawler will hit 
         # https://${gitHub.url}/api/v3/orgs/${organizationName}/repos
         organizationName: MyOrganization
         # default is false - API URL is slightly different depending on whether you're crawling an organization (most common case) or a user's repositories
diff --git a/github-crawler-autoconfigure/src/main/kotlin/com/societegenerale/githubcrawler/config/GitHubConfiguration.kt b/github-crawler-autoconfigure/src/main/kotlin/com/societegenerale/githubcrawler/config/GitHubConfiguration.kt
index 9c9a507..7d542e6 100644
--- a/github-crawler-autoconfigure/src/main/kotlin/com/societegenerale/githubcrawler/config/GitHubConfiguration.kt
+++ b/github-crawler-autoconfigure/src/main/kotlin/com/societegenerale/githubcrawler/config/GitHubConfiguration.kt
@@ -4,6 +4,7 @@ package com.societegenerale.githubcrawler.config
 import com.societegenerale.githubcrawler.GitHubCrawlerProperties
 import com.societegenerale.githubcrawler.remote.RemoteGitHubImpl
 import com.societegenerale.githubcrawler.remote.RemoteSourceControl
+import org.slf4j.LoggerFactory
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
@@ -12,10 +13,22 @@ import org.springframework.context.annotation.Configuration
 @ConditionalOnProperty(prefix = "crawler.source-control", name = ["type"], havingValue = "GITHUB")
 open class GitHubConfiguration {
 
+    val log = LoggerFactory.getLogger(this.javaClass)
+
     @Bean
     open fun remoteGitHub(gitHubCrawlerProperties: GitHubCrawlerProperties): RemoteSourceControl {
 
-        return RemoteGitHubImpl(gitHubCrawlerProperties.sourceControl.url,
+        val targetUrl:String
+
+        if(gitHubCrawlerProperties.sourceControl.url.isEmpty()){
+            log.info("'source-control.url' is not provided - defaulting to "+RemoteGitHubImpl.GITHUB_URL)
+            targetUrl = RemoteGitHubImpl.GITHUB_URL
+        }
+        else{
+            targetUrl=gitHubCrawlerProperties.sourceControl.url
+        }
+
+        return RemoteGitHubImpl(targetUrl,
                                 gitHubCrawlerProperties.sourceControl.crawlUsersRepoInsteadOfOrgasRepos,
                                 gitHubCrawlerProperties.sourceControl.apiToken)
     }
diff --git a/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/ConfigValidator.kt b/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/ConfigValidator.kt
index f766580..ddb2a6f 100644
--- a/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/ConfigValidator.kt
+++ b/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/ConfigValidator.kt
@@ -17,8 +17,9 @@ class ConfigValidator(val properties : GitHubCrawlerProperties,
 
         val validationErrors = mutableListOf<String>()
 
-        // there's a default url for AzureDevops, no need to configure it
-        if(properties.sourceControl.type!= SourceControlType.AZURE_DEVOPS &&
+        // there's a default url for AzureDevops and GitHub, no need to configure it
+        if(properties.sourceControl.type != SourceControlType.AZURE_DEVOPS &&
+            properties.sourceControl.type != SourceControlType.GITHUB &&
            properties.sourceControl.url.isBlank()){
             validationErrors.add("source-control.url can't be empty")
         }
@@ -28,10 +29,10 @@ class ConfigValidator(val properties : GitHubCrawlerProperties,
         }
 
         if(validationErrors.isNotEmpty()){
-            return ImmutableList.copyOf(validationErrors);
+            return ImmutableList.copyOf(validationErrors)
         }
 
-        val organizationName=properties.sourceControl.organizationName;
+        val organizationName=properties.sourceControl.organizationName
 
         try{
             remoteSourceControl.validateRemoteConfig(organizationName)
@@ -50,7 +51,7 @@ class ConfigValidator(val properties : GitHubCrawlerProperties,
             return ImmutableList.of(errorMessage)
         }
 
-        return ImmutableList.of();
+        return ImmutableList.of()
 
     }
 
diff --git a/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/remote/RemoteGitHubImpl.kt b/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/remote/RemoteGitHubImpl.kt
index b5c9302..77de868 100644
--- a/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/remote/RemoteGitHubImpl.kt
+++ b/github-crawler-core/src/main/kotlin/com/societegenerale/githubcrawler/remote/RemoteGitHubImpl.kt
@@ -46,6 +46,7 @@ import java.lang.reflect.Type
 class RemoteGitHubImpl @JvmOverloads constructor(val gitHubUrl: String, val usersReposInsteadOfOrgasRepos: Boolean = false, val apiKey: String) : RemoteSourceControl {
 
     companion object {
+        const val GITHUB_URL= "https://api.github.com"
         const val REPO_LEVEL_CONFIG_FILE = ".githubCrawler"
         const val APPLICATION_JSON = "application/json"
         const val ACCEPT = "accept"
@@ -223,7 +224,7 @@ class RemoteGitHubImpl @JvmOverloads constructor(val gitHubUrl: String, val user
 
         val searchCodeUrl = HttpUrl.parse(gitHubUrl +buildQueryString(query,repositoryFullName))!!.newBuilder().build().toString()
 
-        log.info("fetching code search result from $searchCodeUrl");
+        log.info("fetching code search result from $searchCodeUrl")
 
         val requestBuilder = okhttp3.Request.Builder()
             .url(searchCodeUrl)
@@ -381,7 +382,7 @@ internal class GiHubErrorDecoder : ErrorDecoder {
             throw GitHubResponseDecoder.GithubException("problem while fetching content... conflict state as per HTTP 409 code")
         }
 
-        return errorStatus(methodKey, response);
+        return errorStatus(methodKey, response)
     }
 }
 
@@ -395,7 +396,7 @@ internal class GitHubResponseDecoder : Decoder {
         repoConfigMapper.registerModule(KotlinModule.Builder().build())
     }
 
-    fun decodeRepoConfig(response: okhttp3.Response): RepositoryConfig {
+    fun decodeRepoConfig(response: Response): RepositoryConfig {
 
         val writer = StringWriter()
         IOUtils.copy(response.body()?.byteStream(), writer, "UTF-8")
@@ -436,7 +437,7 @@ internal class GitHubResponseDecoder : Decoder {
         }
     }
 
-    private fun parseRepositoryConfigResponse(responseAsString: String, response: okhttp3.Response): RepositoryConfig {
+    private fun parseRepositoryConfigResponse(responseAsString: String, response: Response): RepositoryConfig {
         if (responseAsString.isEmpty()) {
             return RepositoryConfig()
         }


Test patch:
diff --git a/github-crawler-core/src/test/java/com/societegenerale/githubcrawler/ConfigValidatorTest.kt b/github-crawler-core/src/test/java/com/societegenerale/githubcrawler/ConfigValidatorTest.kt
index be15c18..738e079 100644
--- a/github-crawler-core/src/test/java/com/societegenerale/githubcrawler/ConfigValidatorTest.kt
+++ b/github-crawler-core/src/test/java/com/societegenerale/githubcrawler/ConfigValidatorTest.kt
@@ -12,14 +12,23 @@ class ConfigValidatorTest {
     private val mockRemoteSourceControl = mock(RemoteSourceControl::class.java)
 
     @Test
-    fun shouldNotHaveEmptyGitHubUrl() {
+    fun shouldNotHaveEmptyGitLabUrl() {
 
-        val configValidator = ConfigValidator(GitHubCrawlerProperties(SourceControlConfig(url = "",organizationName="notEmpty")),mockRemoteSourceControl)
+        val configValidator = ConfigValidator(GitHubCrawlerProperties(SourceControlConfig(type=SourceControlType.GITLAB, url = "",organizationName="notEmpty")),mockRemoteSourceControl)
 
         assertThat(configValidator.getValidationErrors()).containsOnly("source-control.url can't be empty");
 
     }
 
+    @Test
+    fun gitHubUrlCanBeEmpty() {
+
+        val configValidator = ConfigValidator(GitHubCrawlerProperties(SourceControlConfig(type=SourceControlType.GITHUB, url = "",organizationName="notEmpty")),mockRemoteSourceControl)
+
+        assertThat(configValidator.getValidationErrors()).isEmpty();
+
+    }
+
     @Test
     fun shouldNotHaveEmptyOrganization() {