Add kubernetes-log4j module

This module adds the ability to Log4j Core to use Kubernetes attributes
in a configuration file.

It is a cleaned-up version of the
`org.apache.logging.log4j:log4j-kubernetes`.

As explained in fabric8io#5682, it does make more sense to host is here since:

 * it only depends on a very stable `StrLookup` dependency from
   `log4j-core`,
 * the number and kind of properties available through
   `kubernetes-client` depend on its version.

log4j/pom.xml

@@ -0,0 +1,89 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright (C) 2015 Red Hat, Inc.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+            http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>io.fabric8</groupId>
+    <artifactId>kubernetes-client-project</artifactId>
+    <version>6.11-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>kubernetes-log4j</artifactId>
+  <packaging>jar</packaging>
+  <name>Fabric8 :: Kubernetes :: Log4j Core components</name>
+  <description>Provides a lookup to use Kubernetes attributes in a Log4j Core configuration.</description>
+
+  <properties>
+    <osgi.export>io.fabric8.kubernetes.log4j.*</osgi.export>
+    <osgi.import>*</osgi.import>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.fabric8</groupId>
+      <artifactId>kubernetes-client</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.fabric8</groupId>
+      <artifactId>kubernetes-model-core</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.logging.log4j</groupId>
+      <artifactId>log4j-core</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-params</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <!-- Replace `jar:jar` execution with `bundle:bundle` -->
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-jar-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>default-jar</id>
+            <phase>none</phase>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.felix</groupId>
+        <artifactId>maven-bundle-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>generate-osgi-bundle</id>
+            <goals>
+              <goal>bundle</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

log4j/src/main/java/io/fabric8/kubernetes/log4j/lookup/ClientBuilder.java

@@ -0,0 +1,69 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.kubernetes.log4j.lookup;
+
+import io.fabric8.kubernetes.client.Config;
+import io.fabric8.kubernetes.client.ConfigBuilder;
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.KubernetesClientBuilder;
+
+/**
+ * Builds a Kubernetes Client.
+ */
+class ClientBuilder {
+
+  public KubernetesClient createClient() {
+    final Config config = kubernetesClientConfig();
+    return config != null ? new KubernetesClientBuilder()
+        .withConfig(config).build() : null;
+  }
+
+  private Config kubernetesClientConfig() {
+    Config base = null;
+    try {
+      base = Config.autoConfigure(null);
+    } catch (Exception ex) {
+      if (ex instanceof NullPointerException) {
+        return null;
+      }
+    }
+    final ClientProperties props = new ClientProperties(base);
+    final Config properties = new ConfigBuilder(base)
+        .withApiVersion(props.getApiVersion())
+        .withCaCertData(props.getCaCertData())
+        .withCaCertFile(props.getCaCertFile())
+        .withClientCertData(props.getClientCertData())
+        .withClientCertFile(props.getClientCertFile())
+        .withClientKeyAlgo(props.getClientKeyAlgo())
+        .withClientKeyData(props.getClientKeyData())
+        .withClientKeyFile(props.getClientKeyFile())
+        .withClientKeyPassphrase(props.getClientKeyPassphrase())
+        .withConnectionTimeout(props.getConnectionTimeout())
+        .withHttpProxy(props.getHttpProxy())
+        .withHttpsProxy(props.getHttpsProxy())
+        .withMasterUrl(props.getMasterUrl())
+        .withNamespace(props.getNamespace())
+        .withNoProxy(props.getNoProxy())
+        .withPassword(props.getPassword())
+        .withProxyPassword(props.getProxyPassword())
+        .withProxyUsername(props.getProxyUsername())
+        .withRequestTimeout(props.getRequestTimeout())
+        .withTrustCerts(props.isTrustCerts())
+        .withUsername(props.getUsername())
+        .build();
+    return properties;
+  }
+}

log4j/src/main/java/io/fabric8/kubernetes/log4j/lookup/ClientProperties.java

@@ -0,0 +1,180 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.fabric8.kubernetes.log4j.lookup;
+
+import io.fabric8.kubernetes.client.Config;
+import org.apache.logging.log4j.util.PropertiesUtil;
+
+import java.time.Duration;
+
+/**
+ * Obtains properties used to configure the Kubernetes client.
+ */
+class ClientProperties {
+
+  private static final String[] PREFIXES = { "log4j2.kubernetes.client.", "spring.cloud.kubernetes.client." };
+  private static final String API_VERSION = "apiVersion";
+  private static final String CA_CERT_FILE = "caCertFile";
+  private static final String CA_CERT_DATA = "caCertData";
+  private static final String CLIENT_CERT_FILE = "clientCertFile";
+  private static final String CLIENT_CERT_DATA = "clientCertData";
+  private static final String CLIENT_KEY_FILE = "clientKeyFile";
+  private static final String CLIENT_KEY_DATA = "clientKeyData";
+  private static final String CLIENT_KEY_ALGO = "clientKeyAlgo";
+  private static final String CLIENT_KEY_PASSPHRASE = "clientKeyPassphrase";
+  private static final String CONNECTION_TIMEOUT = "connectionTimeout";
+  private static final String HTTP_PROXY = "httpProxy";
+  private static final String HTTPS_PROXY = "httpsProxy";
+  private static final String LOGGING_INTERVAL = "loggingInterval";
+  private static final String MASTER_URL = "masterUrl";
+  private static final String NAMESPACE = "namespace";
+  private static final String NO_PROXY = "noProxy";
+  private static final String PASSWORD = "password";
+  private static final String PROXY_USERNAME = "proxyUsername";
+  private static final String PROXY_PASSWORD = "proxyPassword";
+  private static final String REQUEST_TIMEOUT = "requestTimeout";
+  private static final String TRUST_CERTS = "trustCerts";
+  private static final String USERNAME = "username";
+  private static final String WATCH_RECONNECT_INTERVAL = "watchReconnectInterval";
+  private static final String WATCH_RECONNECT_LIMIT = "watchReconnectLimit";
+
+  private final PropertiesUtil props = PropertiesUtil.getProperties();
+  private final Config base;
+
+  public ClientProperties(final Config base) {
+    this.base = base;
+  }
+
+  public String getApiVersion() {
+    return props.getStringProperty(PREFIXES, API_VERSION, base::getApiVersion);
+  }
+
+  public String getCaCertFile() {
+    return props.getStringProperty(PREFIXES, CA_CERT_FILE, base::getCaCertFile);
+  }
+
+  public String getCaCertData() {
+    return props.getStringProperty(PREFIXES, CA_CERT_DATA, base::getCaCertData);
+  }
+
+  public String getClientCertFile() {
+    return props.getStringProperty(PREFIXES, CLIENT_CERT_FILE, base::getClientCertFile);
+  }
+
+  public String getClientCertData() {
+    return props.getStringProperty(PREFIXES, CLIENT_CERT_DATA, base::getClientCertData);
+  }
+
+  public String getClientKeyFile() {
+    return props.getStringProperty(PREFIXES, CLIENT_KEY_FILE, base::getClientKeyFile);
+  }
+
+  public String getClientKeyData() {
+    return props.getStringProperty(PREFIXES, CLIENT_KEY_DATA, base::getClientKeyData);
+  }
+
+  public String getClientKeyAlgo() {
+    return props.getStringProperty(PREFIXES, CLIENT_KEY_ALGO, base::getClientKeyAlgo);
+  }
+
+  public String getClientKeyPassphrase() {
+    return props.getStringProperty(PREFIXES, CLIENT_KEY_PASSPHRASE, base::getClientKeyPassphrase);
+  }
+
+  public int getConnectionTimeout() {
+    final Duration timeout = props.getDurationProperty(PREFIXES, CONNECTION_TIMEOUT, null);
+    if (timeout != null) {
+      return (int) timeout.toMillis();
+    }
+    return base.getConnectionTimeout();
+  }
+
+  public String getHttpProxy() {
+    return props.getStringProperty(PREFIXES, HTTP_PROXY, base::getHttpProxy);
+  }
+
+  public String getHttpsProxy() {
+    return props.getStringProperty(PREFIXES, HTTPS_PROXY, base::getHttpsProxy);
+  }
+
+  public int getLoggingInterval() {
+    final Duration interval = props.getDurationProperty(PREFIXES, LOGGING_INTERVAL, null);
+    if (interval != null) {
+      return (int) interval.toMillis();
+    }
+    return base.getLoggingInterval();
+  }
+
+  public String getMasterUrl() {
+    return props.getStringProperty(PREFIXES, MASTER_URL, base::getMasterUrl);
+  }
+
+  public String getNamespace() {
+    return props.getStringProperty(PREFIXES, NAMESPACE, base::getNamespace);
+  }
+
+  public String[] getNoProxy() {
+    final String result = props.getStringProperty(PREFIXES, NO_PROXY, null);
+    if (result != null) {
+      return result.replace("\\s", "").split(",");
+    }
+    return base.getNoProxy();
+  }
+
+  public String getPassword() {
+    return props.getStringProperty(PREFIXES, PASSWORD, base::getPassword);
+  }
+
+  public String getProxyUsername() {
+    return props.getStringProperty(PREFIXES, PROXY_USERNAME, base::getProxyUsername);
+  }
+
+  public String getProxyPassword() {
+    return props.getStringProperty(PREFIXES, PROXY_PASSWORD, base::getProxyPassword);
+  }
+
+  public int getRequestTimeout() {
+    final Duration interval = props.getDurationProperty(PREFIXES, REQUEST_TIMEOUT, null);
+    if (interval != null) {
+      return (int) interval.toMillis();
+    }
+    return base.getRequestTimeout();
+  }
+
+  public Boolean isTrustCerts() {
+    return props.getBooleanProperty(PREFIXES, TRUST_CERTS, base::isTrustCerts);
+  }
+
+  public String getUsername() {
+    return props.getStringProperty(PREFIXES, USERNAME, base::getUsername);
+  }
+
+  public int getWatchReconnectInterval() {
+    final Duration interval = props.getDurationProperty(PREFIXES, WATCH_RECONNECT_INTERVAL, null);
+    if (interval != null) {
+      return (int) interval.toMillis();
+    }
+    return base.getWatchReconnectInterval();
+  }
+
+  public int getWatchReconnectLimit() {
+    final Duration interval = props.getDurationProperty(PREFIXES, WATCH_RECONNECT_LIMIT, null);
+    if (interval != null) {
+      return (int) interval.toMillis();
+    }
+    return base.getWatchReconnectLimit();
+  }
+}