[CAMEL-15196] adds support for opentracing tags

components/camel-opentracing/src/main/docs/opentracing.adoc

@@ -104,3 +104,32 @@ You can find an example demonstrating the three ways to configure OpenTracing he
 https://github.com/apache/camel-spring-boot-examples/tree/master/camel-example-spring-boot-opentracing[camel-example-spring-boot-opentracing]
 
 include::camel-spring-boot::page$opentracing-starter.adoc[]
+
+== Span Operations Processors
+
+The OpenTracing Component exposes the Java API span operations as a set of Processors: `TagProcessor`, `SetBaggageProcessor`, and `GetBaggageProcessor`.
+
+=== Example
+
+[source,java]
+---------------------------------------------------------------------------------------------------------
+from("seda:a").routeId("a")
+        .process(new SetBaggageProcessor("a-baggage", simple("${header.request-header}")))
+        .to("seda:b")
+        .to("seda:c");
+
+from("seda:b").routeId("b")
+        .process(new TagProcessor("b-tag", simple("${header.request-header}")));
+
+from("seda:c").routeId("c")
+        .process(new GetBaggageProcessor("a-baggage", "baggage-header"));
+---------------------------------------------------------------------------------------------------------
+
+Where the value of header "request-header" is "foo", the resulting trace from executing route "seda:a" would include:
+
+* Span "a" with a baggage item named "a-baggage" of value "foo"
+* Span "b" with a tag named "b-tag" of value "foo"
+
+and the resulting message would contain:
+
+* Header "baggage-header" of value "foo"

components/camel-opentracing/src/main/java/org/apache/camel/opentracing/GetBaggageProcessor.java

@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.camel.opentracing;
+
+import io.opentracing.Span;
+import org.apache.camel.AsyncCallback;
+import org.apache.camel.Exchange;
+import org.apache.camel.Expression;
+import org.apache.camel.Traceable;
+import org.apache.camel.spi.IdAware;
+import org.apache.camel.spi.RouteIdAware;
+import org.apache.camel.support.AsyncProcessorSupport;
+import org.apache.camel.util.ObjectHelper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A processor which gets a baggage item from the active {@link Span} and sets it as a Header
+ */
+public class GetBaggageProcessor extends AsyncProcessorSupport implements Traceable, IdAware, RouteIdAware {
+
+    private static final Logger LOG = LoggerFactory.getLogger(GetBaggageProcessor.class);
+
+    private String id;
+    private String routeId;
+    private final String headerName;
+    private final String baggageName;
+
+    public GetBaggageProcessor(String baggageName, String headerName) {
+        this.baggageName = baggageName;
+        this.headerName = headerName;
+        ObjectHelper.notNull(baggageName, "baggageName");
+        ObjectHelper.notNull(headerName, "headerName");
+    }
+
+    @Override
+    public boolean process(Exchange exchange, AsyncCallback callback) {
+        try {
+            Span span = ActiveSpanManager.getSpan(exchange);
+            if (span != null) {
+                String item = span.getBaggageItem(baggageName);
+                exchange.getMessage().setHeader(headerName, item);
+            } else {
+                LOG.warn("OpenTracing: could not find managed span for exchange={}", exchange);
+            }
+        } catch (Exception e) {
+            exchange.setException(e);
+        } finally {
+            // callback must be invoked
+            callback.done(true);
+        }
+
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return id;
+    }
+
+    @Override
+    public String getTraceLabel() {
+        return "getBaggage[" + baggageName + ", " + headerName + "]";
+    }
+
+    @Override
+    public String getId() {
+        return id;
+    }
+
+    @Override
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    @Override
+    public String getRouteId() {
+        return routeId;
+    }
+
+    @Override
+    public void setRouteId(String routeId) {
+        this.routeId = routeId;
+    }
+
+    public String getBaggageName() {
+        return baggageName;
+    }
+
+    public String getHeaderName() {
+        return headerName;
+    }
+
+    @Override
+    protected void doStart() throws Exception {
+        // noop
+    }
+
+    @Override
+    protected void doStop() throws Exception {
+        // noop
+    }
+}

components/camel-opentracing/src/main/java/org/apache/camel/opentracing/SetBaggageProcessor.java

@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.camel.opentracing;
+
+import io.opentracing.Span;
+import org.apache.camel.AsyncCallback;
+import org.apache.camel.Exchange;
+import org.apache.camel.Expression;
+import org.apache.camel.Traceable;
+import org.apache.camel.spi.IdAware;
+import org.apache.camel.spi.RouteIdAware;
+import org.apache.camel.support.AsyncProcessorSupport;
+import org.apache.camel.util.ObjectHelper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A processor which adds a baggage item on the active {@link Span} with an {@link Expression}
+ */
+public class SetBaggageProcessor extends AsyncProcessorSupport implements Traceable, IdAware, RouteIdAware {
+
+    private static final Logger LOG = LoggerFactory.getLogger(SetBaggageProcessor.class);
+
+    private String id;
+    private String routeId;
+    private final String baggageName;
+    private final Expression expression;
+
+    public SetBaggageProcessor(String baggageName, Expression expression) {
+        this.baggageName = baggageName;
+        this.expression = expression;
+        ObjectHelper.notNull(baggageName, "baggageName");
+        ObjectHelper.notNull(expression, "expression");
+    }
+
+    @Override
+    public boolean process(Exchange exchange, AsyncCallback callback) {
+        try {
+            Span span = ActiveSpanManager.getSpan(exchange);
+            if (span != null) {
+                String item = expression.evaluate(exchange, String.class);
+                span.setBaggageItem(baggageName, item);
+            } else {
+                LOG.warn("OpenTracing: could not find managed span for exchange={}", exchange);
+            }
+        } catch (Exception e) {
+            exchange.setException(e);
+        } finally {
+            // callback must be invoked
+            callback.done(true);
+        }
+
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return id;
+    }
+
+    @Override
+    public String getTraceLabel() {
+        return "setBaggage[" + baggageName + ", " + expression + "]";
+    }
+
+    @Override
+    public String getId() {
+        return id;
+    }
+
+    @Override
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    @Override
+    public String getRouteId() {
+        return routeId;
+    }
+
+    @Override
+    public void setRouteId(String routeId) {
+        this.routeId = routeId;
+    }
+
+    public String getBaggageName() {
+        return baggageName.toString();
+    }
+
+    public Expression getExpression() {
+        return expression;
+    }
+
+    @Override
+    protected void doStart() throws Exception {
+        // noop
+    }
+
+    @Override
+    protected void doStop() throws Exception {
+        // noop
+    }
+}

components/camel-opentracing/src/main/java/org/apache/camel/opentracing/TagProcessor.java

@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.camel.opentracing;
+
+import io.opentracing.Span;
+import org.apache.camel.AsyncCallback;
+import org.apache.camel.Exchange;
+import org.apache.camel.Expression;
+import org.apache.camel.Traceable;
+import org.apache.camel.spi.IdAware;
+import org.apache.camel.spi.RouteIdAware;
+import org.apache.camel.support.AsyncProcessorSupport;
+import org.apache.camel.util.ObjectHelper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A processor which adds a tag on the active {@link io.opentracing.Span} with an {@link org.apache.camel.Expression}
+ */
+public class TagProcessor extends AsyncProcessorSupport implements Traceable, IdAware, RouteIdAware {
+
+    private static final Logger LOG = LoggerFactory.getLogger(TagProcessor.class);
+
+    private String id;
+    private String routeId;
+    private final String tagName;
+    private final Expression expression;
+
+    public TagProcessor(String tagName, Expression expression) {
+        this.tagName = tagName;
+        this.expression = expression;
+        ObjectHelper.notNull(tagName, "tagName");
+        ObjectHelper.notNull(expression, "expression");
+    }
+
+    @Override
+    public boolean process(Exchange exchange, AsyncCallback callback) {
+        try {
+            Span span = ActiveSpanManager.getSpan(exchange);
+            if (span != null) {
+                String tag = expression.evaluate(exchange, String.class);
+                span.setTag(tagName, tag);
+            } else {
+                LOG.warn("OpenTracing: could not find managed span for exchange={}", exchange);
+            }
+        } catch (Exception e) {
+            exchange.setException(e);
+        } finally {
+            // callback must be invoked
+            callback.done(true);
+        }
+
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return id;
+    }
+
+    @Override
+    public String getTraceLabel() {
+        return "tag[" + tagName + ", " + expression + "]";
+    }
+
+    @Override
+    public String getId() {
+        return id;
+    }
+
+    @Override
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    @Override
+    public String getRouteId() {
+        return routeId;
+    }
+
+    @Override
+    public void setRouteId(String routeId) {
+        this.routeId = routeId;
+    }
+
+    public String getTagName() {
+        return tagName;
+    }
+
+    public Expression getExpression() {
+        return expression;
+    }
+
+    @Override
+    protected void doStart() throws Exception {
+        // noop
+    }
+
+    @Override
+    protected void doStop() throws Exception {
+        // noop
+    }
+}