properties:key[?options]

Where key is the key for the property to lookup

The Properties component supports 15 options which are listed below.

{% raw %}

{% endraw %}

The Properties component supports 7 endpoint options which are listed below:

{% raw %}

{% endraw %}

	Tip
	Resolving property from Java code You can use the method resolvePropertyPlaceholders on the CamelContext to resolve a property from any Java code.

Available as of Camel 2.3

Camel now provides a new PropertiesComponent in camel-core which allows you to use property placeholders when defining Camel Endpoint URIs.

This works much like you would do if using Spring’s <property-placeholder> tag. However Spring have a limitation which prevents 3rd party frameworks to leverage Spring property placeholders to the fullest. See more at How do I use Spring Property Placeholder with Camel XML.

	Tip
	Bridging Spring and Camel property placeholders From Camel 2.10 onwards, you can bridge the Spring property placeholder with Camel, see further below for more details.

The property placeholder is generally in use when doing:

The syntax to use Camel’s property placeholder is to use {{key}} for example {{file.uri}} where file.uri is the property key.

You can use property placeholders in parts of the endpoint URI’s which for example you can use placeholders for parameters in the URIs.

From Camel 2.14.1 onwards you can specify a default value to use if a property with the key does not exists, eg file.url:/some/path where the default value is the text after the colon (eg /some/path).

	Note
	Do not use colon in the property key. The colon is used as a separator token when you are providing a default value, which is supported from Camel 2.14.1 onwards.

Camel provides a pluggable mechanism which allows 3rd part to provide their own resolver to lookup properties. Camel provides a default implementation org.apache.camel.component.properties.DefaultPropertiesResolver which is capable of loading properties from the file system, classpath or Registry. You can prefix the locations with either:

The PropertiesResolver need to know a location(s) where to resolve the properties. You can define 1 to many locations. If you define the location in a single String property you can separate multiple locations with comma such as:

pc.setLocation("com/mycompany/myprop.properties,com/mycompany/other.properties");

location=file:${karaf.home}/etc/foo.properties

location=file:${env:APP_HOME}/etc/foo.properties

location=file:${env:APP_HOME}/etc/${prop.name}.properties

dev.endpoint = result1
test.endpoint = result2

PropertiesComponent pc = context.getComponent("properties", PropertiesComponent.class);
pc.setPropertyPrefix("${stage}.");
// ...
context.addRoutes(new RouteBuilder() {
    @Override
    public void configure() throws Exception {
        from("direct:start").to("properties:mock:{{endpoint}}");
    }
});

You have to create and register the PropertiesComponent under the name properties such as:

PropertiesComponent pc = new PropertiesComponent();
pc.setLocation("classpath:com/mycompany/myprop.properties");
context.addComponent("properties", pc);

Spring XML offers two variations to configure. You can define a spring bean as a PropertiesComponent which resembles the way done in Java DSL. Or you can use the <propertyPlaceholder> tag.

<bean id="properties" class="org.apache.camel.component.properties.PropertiesComponent">
    <property name="location" value="classpath:com/mycompany/myprop.properties"/>
</bean>

Using the <propertyPlaceholder> tag makes the configuration a bit more fresh such as:

<camelContext ...>
   <propertyPlaceholder id="properties" location="com/mycompany/myprop.properties"/>
</camelContext>

	Tip
	Specifying the cache option inside XML Camel 2.10 onwards supports specifying a value for the cache option both inside the Spring as well as the Blueprint XML.

Available as of Camel 2.4 For example in OSGi you may want to expose a service which returns the properties as a java.util.Properties object.

Then you could setup the Properties component as follows:

   <propertyPlaceholder id="properties" location="ref:myProperties"/>

Where myProperties is the id to use for lookup in the OSGi registry. Notice we use the ref: prefix to tell Camel that it should lookup the properties for the Registry.

When using property placeholders in the endpoint URIs you can either use the properties: component or define the placeholders directly in the URI. We will show example of both cases, starting with the former.

// properties
cool.end=mock:result

// route
from("direct:start").to("properties:{{cool.end}}");

You can also use placeholders as a part of the endpoint uri:

// properties
cool.foo=result

// route
from("direct:start").to("properties:mock:{{cool.foo}}");

In the example above the to endpoint will be resolved to mock:result.

You can also have properties with refer to each other such as:

// properties
cool.foo=result
cool.concat=mock:{{cool.foo}}

// route
from("direct:start").to("properties:mock:{{cool.concat}}");

Notice how cool.concat refer to another property.

The properties: component also offers you to override and provide a location in the given uri using the locations option:

   from("direct:start").to("properties:bar.end?locations=com/mycompany/bar.properties");

You can also use property placeholders directly in the endpoint uris without having to use properties:.

// properties
cool.foo=result

// route
from("direct:start").to("mock:{{cool.foo}}");

And you can use them in multiple wherever you want them:

// properties
cool.start=direct:start
cool.showid=true
cool.result=result

// route
from("{{cool.start}}")
    .to("log:{{cool.start}}?showBodyType=false&showExchangeId={{cool.showid}}")
    .to("mock:{{cool.result}}");

You can also your property placeholders when using ProducerTemplate for example:

template.sendBody("{{cool.start}}", "Hello World");

The Simple language now also support using property placeholders, for example in the route below:

// properties
cheese.quote=Camel rocks

// route
from("direct:start")
    .transform().simple("Hi ${body} do you think ${properties:cheese.quote}?");

You can also specify the location in the Simple language for example:

// bar.properties
bar.quote=Beer tastes good

// route
from("direct:start")
    .transform().simple("Hi ${body}. ${properties:com/mycompany/bar.properties:bar.quote}.");

The property placeholders is also supported in many of the Camel Spring XML tags such as <package>, <packageScan>, <contextScan>, <jmxAgent>, <endpoint>, <routeBuilder>, <proxy> and the others.

The example below has property placeholder in the <jmxAgent> tag:

You can also define property placeholders in the various attributes on the <camelContext> tag such as trace as shown here:

Available as of Camel 2.5 It is possible to override a property value at runtime using a JVM System property without the need to restart the application to pick up the change. This may also be accomplished from the command line by creating a JVM System property of the same name as the property it replaces with a new value. An example of this is given below

PropertiesComponent pc = context.getComponent("properties", PropertiesComponent.class);
pc.setCache(false);

System.setProperty("cool.end", "mock:override");
System.setProperty("cool.result", "override");

context.addRoutes(new RouteBuilder() {
    @Override
    public void configure() throws Exception {
        from("direct:start").to("properties:cool.end");
        from("direct:foo").to("properties:mock:{{cool.result}}");
    }
});
context.start();

getMockEndpoint("mock:override").expectedMessageCount(2);

template.sendBody("direct:start", "Hello World");
template.sendBody("direct:foo", "Hello Foo");

System.clearProperty("cool.end");
System.clearProperty("cool.result");

assertMockEndpointsSatisfied();

Available as of Camel 2.7

	Note
	If you use OSGi Blueprint then this only works from 2.11.1 or 2.10.5 onwards.

Previously it was only the xs:string type attributes in the XML DSL that support placeholders. For example often a timeout attribute would be a xs:int type and thus you cannot set a string value as the placeholder key. This is now possible from Camel 2.7 onwards using a special placeholder namespace.

In the example below we use the prop prefix for the namespace http://camel.apache.org/schema/placeholder by which we can use the prop prefix in the attributes in the XML DSLs. Notice how we use that in the Multicast to indicate that the option stopOnException should be the value of the placeholder with the key "stop".

In our properties file we have the value defined as

stop=true

Available as of Camel 2.7

Likewise we have added support for defining placeholders in the Java DSL using the new placeholder DSL as shown in the following equivalent example:

Available as of Camel 2.7

Camel supports Blueprint which also offers a property placeholder service. Camel supports convention over configuration, so all you have to do is to define the OSGi Blueprint property placeholder in the XML file as shown below:

{% raw %}

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0"
           xsi:schemaLocation="
           http://www.osgi.org/xmlns/blueprint/v1.0.0 https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">

    <!-- OSGI blueprint property placeholder -->
    <cm:property-placeholder id="myblueprint.placeholder" persistent-id="camel.blueprint">
        <!-- list some properties as needed -->
        <cm:default-properties>
            <cm:property name="result" value="mock:result"/>
        </cm:default-properties>
    </cm:property-placeholder>

    <camelContext xmlns="http://camel.apache.org/schema/blueprint">
        <!-- in the route we can use {{ }} placeholders which will lookup in blueprint
             as Camel will auto detect the OSGi blueprint property placeholder and use it -->
        <route>
            <from uri="direct:start"/>
            <to uri="mock:foo"/>
            <to uri="{{result}}"/>
        </route>
    </camelContext>
</blueprint>

{% endraw %}

Using OSGi blueprint property placeholders in Camel routes

By default Camel detects and uses OSGi blueprint property placeholder service. You can disable this by setting the attribute useBlueprintPropertyResolver to false on the <camelContext> definition.

Note

About placeholder syntaxes Notice how we can use the Camel syntax for placeholders {{ and }} in the Camel route, which will lookup the value from OSGi blueprint. The blueprint syntax for placeholders is ${ }. So outside the <camelContext> you must use the ${ } syntax. Where as inside <camelContext> you must use {{ and }} syntax. OSGi blueprint allows you to configure the syntax, so you can actually align those if you want.

You can also explicit refer to a specific OSGi blueprint property placeholder by its id. For that you need to use the Camel’s <propertyPlaceholder> as shown in the example below:

{% raw %}

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0"
           xsi:schemaLocation="
           http://www.osgi.org/xmlns/blueprint/v1.0.0 https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">

    <!-- OSGI blueprint property placeholder -->
    <cm:property-placeholder id="myblueprint.placeholder" persistent-id="camel.blueprint">
        <!-- list some properties as needed -->
        <cm:default-properties>
            <cm:property name="prefix.result" value="mock:result"/>
        </cm:default-properties>
    </cm:property-placeholder>

    <camelContext xmlns="http://camel.apache.org/schema/blueprint">
        <!-- using Camel properties component and refer to the blueprint property placeholder by its id -->
        <propertyPlaceholder id="properties" location="blueprint:myblueprint.placeholder"
                             prefixToken="[[" suffixToken="]]"
                             propertyPrefix="prefix."/>

        <!-- in the route we can use {{ }} placeholders which will lookup in blueprint -->
        <route>
            <from uri="direct:start"/>
            <to uri="mock:foo"/>
            <to uri="[[result]]"/>
        </route>
    </camelContext>
</blueprint>

{% endraw %}

Explicit referring to a OSGi blueprint placeholder in Camel

Notice how we use the blueprint scheme to refer to the OSGi blueprint placeholder by its id. This allows you to mix and match, for example you can also have additional schemes in the location. For example to load a file from the classpath you can do:

location="blueprint:myblueprint.placeholder,classpath:myproperties.properties"

Each location is separated by comma.

## this is a comment
greeting=Bye

greeting=Bye
echo=Yay
destination=mock:result

Available as of Camel 2.10

The Spring Framework does not allow 3rd party frameworks such as Apache Camel to seamless hook into the Spring property placeholder mechanism. However you can easily bridge Spring and Camel by declaring a Spring bean with the type org.apache.camel.spring.spi.BridgePropertyPlaceholderConfigurer, which is a Spring org.springframework.beans.factory.config.PropertyPlaceholderConfigurer type.

To bridge Spring and Camel you must define a single bean as shown below:

Bridging Spring and Camel property placeholders

You must not use the spring <context:property-placeholder> namespace at the same time; this is not possible.

After declaring this bean, you can define property placeholders using both the Spring style, and the Camel style within the <camelContext> tag as shown below:

Using bridge property placeholders

Notice how the hello bean is using pure Spring property placeholders using the ${ } notation. And in the Camel routes we use the Camel placeholder notation with {{ and }}.

<setHeader headerName="Exchange.FILE_NAME">
  <simple>{{file.rootdir}}/${in.header.CamelFileName}</simple>
</setHeader>

<setHeader headerName="Exchange.FILE_NAME">
  <simple>{{file.rootdir}}/$simple{in.header.CamelFileName}</simple>
</setHeader>

Available as of Camel 2.10

When Testing with Camel and using the Properties component, you may want to be able to provide the properties to be used from directly within the unit test source code. This is now possible from Camel 2.10 onwards, as the Camel test kits, eg CamelTestSupport class offers the following methods

So for example in your unit test classes, you can override the useOverridePropertiesWithPropertiesComponent method and return a java.util.Properties that contains the properties which should be preferred to be used.

Providing properties from within unit test source

This can be done from any of the Camel Test kits, such as camel-test, camel-test-spring, and camel-test-blueprint.

The ignoreMissingLocationWithPropertiesComponent can be used to instruct Camel to ignore any locations which was not discoverable, for example if you run the unit test, in an environment that does not have access to the location of the properties.

Available as of Camel 2.12

Camel allows to inject property placeholders in POJOs using the @PropertyInject annotation which can be set on fields and setter methods.

For example you can use that with RouteBuilder classes, such as shown below:

public class MyRouteBuilder extends RouteBuilder {

    @PropertyInject("hello")
    private String greeting;

    @Override
    public void configure() throws Exception {
        from("direct:start")
            .transform().constant(greeting)
            .to("{{result}}");
    }

}

Notice we have annotated the greeting field with @PropertyInject and define it to use the key "hello". Camel will then lookup the property with this key and inject its value, converted to a String type.

You can also use multiple placeholders and text in the key, for example we can do:

    @PropertyInject("Hello {{name}} how are you?")
    private String greeting;

This will lookup the placeholder with they key "name".

You can also add a default value if the key does not exists, such as:

    @PropertyInject(value = "myTimeout", defaultValue = "5000")
    private int timeout;

Available as of Camel 2.14.1

The Properties component includes the following functions out of the box

As you can see these functions is intended to make it easy to lookup values from the environment. As they are provided out of the box, they can easily be used as shown below:

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">

    <route>
      <from uri="direct:start"/>
      <to uri="{`{env:SOMENAME}`}"/>
      <to uri="{`{sys:MyJvmPropertyName}`}"/>
    </route>
  </camelContext>

You can use default values as well, so if the property does not exists, you can define a default value as shown below, where the default value is a log:foo and log:bar value.

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">

    <route>
      <from uri="direct:start"/>
      <to uri="{`{env:SOMENAME:log:foo}`}"/>
      <to uri="{`{sys:MyJvmPropertyName:log:bar}`}"/>
    </route>
  </camelContext>

The service function is for looking up a service which is defined using OS environment variables using the service naming idiom, to refer to a service location using hostname : port

in other words the service uses _SERVICE_HOST and _SERVICE_PORT as prefix. So if the service is named FOO, then the OS environment variables should be set as

export $FOO_SERVICE_HOST=myserver
export $FOO_SERVICE_PORT=8888

For example if the FOO service a remote HTTP service, then we can refer to the service in the Camel endpoint uri, and use the HTTP component to make the HTTP call:

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">

    <route>
      <from uri="direct:start"/>
      <to uri="http://{`{service:FOO}`}/myapp"/>
    </route>
  </camelContext>

And we can use default values if the service has not been defined, for example to call a service on localhost, maybe for unit testing etc

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">

    <route>
      <from uri="direct:start"/>
      <to uri="http://{`{service:FOO:localhost:8080}`}/myapp"/>
    </route>
  </camelContext>

Available as of Camel 2.14.1

The Properties component allow to plugin 3rd party functions which can be used during parsing of the property placeholders. These functions are then able to do custom logic to resolve the placeholders, such as looking up in databases, do custom computations, or whatnot. The name of the function becomes the prefix used in the placeholder. This is best illustrated in the example code below

  <bean id="beerFunction" class="MyBeerFunction"/>

  <camelContext xmlns="http://camel.apache.org/schema/blueprint">
    <propertyPlaceholder id="properties" location="none" ignoreMissingLocation="true">
      <propertiesFunction ref="beerFunction"/>
    </propertyPlaceholder>

    <route>
      <from uri="direct:start"/>
      <to uri="{`{beer:FOO}`}"/>
      <to uri="{`{beer:BAR}`}"/>
    </route>
  </camelContext>

Here we have a Camel XML route where we have defined the <propertyPlaceholder> to use a custom function, which we refer to be the bean id - eg the beerFunction. As the beer function uses "beer" as its name, then the placeholder syntax can trigger the beer function by starting with beer:value.

The implementation of the function is only two methods as shown below:

    public static final class MyBeerFunction implements PropertiesFunction {

        @Override
        public String getName() {
            return "beer";
        }

        @Override
        public String apply(String remainder) {
            return "mock:" + remainder.toLowerCase();
        }
    }

The function must implement the org.apache.camel.component.properties.PropertiesFunction interface. The method getName is  the name of the function, eg beer. And the apply method is where we implement the custom logic to do. As the sample code is from an unit test, it just returns a value to refer to a mock endpoint.

To register a custom function from Java code is as shown below:

        PropertiesComponent pc = context.getComponent("properties", PropertiesComponent.class);
        pc.addFunction(new MyBeerFunction());