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commit 33232b5449f595cb73c559cce324355dec338e7d Author: Claus Ibsen <[email protected]> AuthorDate: Wed Aug 18 18:11:01 2021 +0200 Polish and cleanup documentation --- .../src/main/docs/properties-component.adoc | 820 +++------------------ 1 file changed, 114 insertions(+), 706 deletions(-) diff --git a/core/camel-base/src/main/docs/properties-component.adoc b/core/camel-base/src/main/docs/properties-component.adoc index 4a7eb02..9115aa0 100644 --- a/core/camel-base/src/main/docs/properties-component.adoc +++ b/core/camel-base/src/main/docs/properties-component.adoc @@ -10,99 +10,27 @@ *Since Camel {since}* The properties component is used for property placeholders in your Camel application, such as endpoint URIs. -It is *not* a regular Camel component with producer and consumer for routing messages. However for historical -reasons it was named `PropertiesComponent` and this name is commonly known and therfore we keep using it. +It is *not* a regular Camel component with producer and consumer for routing messages. +However, for historical reasons it was named `PropertiesComponent` and this name is commonly known so we keep using it. -== Spring Boot Auto-Configuration - -The component supports 10 options, which are listed below. - - - -[width="100%",cols="2,5,^1,2",options="header"] -|=== -| Name | Description | Default | Type -| *camel.component.properties.auto-discover-properties-sources* | Whether to automatically discovery instances of PropertiesSource from registry and service factory. | true | Boolean -| *camel.component.properties.default-fallback-enabled* | If false, the component does not attempt to find a default for the key by looking after the colon separator. | true | Boolean -| *camel.component.properties.encoding* | Encoding to use when loading properties file from the file system or classpath. If no encoding has been set, then the properties files is loaded using ISO-8859-1 encoding (latin-1) as documented by java.util.Properties#load(java.io.InputStream) | | String -| *camel.component.properties.environment-variable-mode* | Sets the OS environment variables mode (0 = never, 1 = fallback, 2 = override). The default mode (override) is to use OS environment variables if present, and override any existing properties. OS environment variable mode is checked before JVM system property mode | 2 | Integer -| *camel.component.properties.ignore-missing-location* | Whether to silently ignore if a location cannot be located, such as a properties file not found. | false | Boolean -| *camel.component.properties.initial-properties* | Sets initial properties which will be used before any locations are resolved. The option is a java.util.Properties type. | | String -| *camel.component.properties.location* | A list of locations to load properties. You can use comma to separate multiple locations. This option will override any default locations and only use the locations from this option. | | String -| *camel.component.properties.override-properties* | Sets a special list of override properties that take precedence and will use first, if a property exist. The option is a java.util.Properties type. | | String -| *camel.component.properties.properties-parser* | To use a custom PropertiesParser. The option is a org.apache.camel.component.properties.PropertiesParser type. | | String -| *camel.component.properties.system-properties-mode* | Sets the JVM system property mode (0 = never, 1 = fallback, 2 = override). The default mode (override) is to use system properties if present, and override any existing properties. OS environment variable mode is checked before JVM system property mode | 2 | Integer -|=== - -[TIP] -**Resolving property from Java code** + -You can use the method `resolvePropertyPlaceholders` on the -`CamelContext` to resolve a property from any Java code. - -== Using PropertyPlaceholder - -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 -xref:manual:faq:how-do-i-use-spring-property-placeholder-with-camel-xml.adoc[How do -I use Spring Property Placeholder with Camel XML]. +IMPORTANT: See the xref:latest@manual:ROOT:using-propertyplaceholder[Property Placeholder] documentation for general information on using property placeholders in Camel. -[TIP] -**Bridging Spring and Camel property placeholders** + -You can bridge the Spring property placeholder -with Camel, see further below for more details. +The properties component requires to load the properties (key=value pairs) from an external source such as `.properties` files. +The component is pluggable and you can configure to use other sources or write a custom implementation (for example to load from a database). -The property placeholder is generally in use when doing: -* lookup or creating endpoints -* lookup of beans in the Registry -* additional supported in Spring XML (see below in examples) -* using Blueprint PropertyPlaceholder with Camel -xref:properties-component.adoc[Properties] component -* using `@PropertyInject` to inject a property in a POJO -* Using default value if a property does not exists -* Include out of the box functions, to lookup property -values from OS environment variables, JVM system properties, or the -service idiom. -* Using custom functions, which can be plugged into the -property component. +== Defining location of properties files -== Syntax - -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. - -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. -==== - -== Defining location - -The properties component needs 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: +The properties component needs to know a location(s) where to resolve the properties. +You can define one to many locations. +Multiple locations can be separated by comma such as: [source,java] ---- pc.setLocation("com/mycompany/myprop.properties,com/mycompany/other.properties"); ---- -You can set which location can be discarded if missing by by setting the ``optional`` attribute, which is false by default, i.e: +You can mark a location to be optional, which means that Camel will ignore the location if not present: [source,java] ---- @@ -111,10 +39,9 @@ pc.setLocations( "com/mycompany/defaults.properties"); ---- -== Using system and environment variables in locations +=== Using system and environment variables in locations -The location now supports using placeholders for JVM system properties -and OS environments variables. +The location now supports using placeholders for JVM system properties and OS environments variables. For example: @@ -123,11 +50,11 @@ For example: location=file:${karaf.home}/etc/foo.properties ---- -In the location above we defined a location using the file scheme using -the JVM system property with key `karaf.home`. +In the location above we defined a location using the file scheme using the JVM system property with key `karaf.home`. To use an OS environment variable instead you would have to prefix with -`env:`. You can also prefix with `env.`, however this style is not recommended because all the other functions use colon. +`env:`. +You can also prefix with `env.`, however this style is not recommended because all the other functions use colon. [source] ---- @@ -138,9 +65,8 @@ Where `APP_HOME` is an OS environment. [NOTE] ==== -Some OS'es (such as Linux) do not support dashes in environment variable names, -so here we are using `APP_HOME`. But if you specify `APP-HOME` then Camel 3 will automatic lookup -the value as `APP_HOME` (with underscore) as fallback. +Some OS'es (such as Linux) do not support dashes in environment variable names, so here we are using `APP_HOME`. +But if you specify `APP-HOME` then Camel 3 will automatic lookup the value as `APP_HOME` (with underscore) as fallback. ==== You can have multiple placeholders in the same location, such as: @@ -150,22 +76,11 @@ You can have multiple placeholders in the same location, such as: location=file:${env:APP_HOME}/etc/${prop.name}.properties ---- -== Configuring in Java DSL - -You have to create and register the `PropertiesComponent` under the name -`properties` such as: - -[source,java] ----- -PropertiesComponent pc = camelContext.getPropertiesComponent(); -pc.setLocation("classpath:com/mycompany/myprop.properties"); ----- - -== Configuring in Spring XML +=== Defining location of properties files in Spring XML -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. +Spring XML offers two variations to configure. +You can define a spring bean as a `PropertiesComponent` which resembles the way done in Java. +Or you can use the `<propertyPlaceholder>` tag. [source,xml] ---- @@ -174,21 +89,20 @@ DSL. Or you can use the `<propertyPlaceholder>` tag. </bean> ---- -Using the `<propertyPlaceholder>` tag makes the configuration a bit more -fresh such as: +Using the `<propertyPlaceholder>` allows to configure this within the `<camelContext>` tag. [source,xml] ---- -<camelContext ...> +<camelContext> <propertyPlaceholder id="properties" location="com/mycompany/myprop.properties"/> </camelContext> ---- -Setting the properties location through the location tag works just fine but sometime you have a number of resources to take into account and starting from *Camel 2.19.0* you can set the properties location with a dedicated propertiesLocation: +For fine grained configuration of the location, then this can be done as follows: [source,xml] ---- -<camelContext ...> +<camelContext> <propertyPlaceholder id="myPropertyPlaceholder"> <propertiesLocation resolver = "classpath" @@ -206,134 +120,9 @@ Setting the properties location through the location tag works just fine but som </camelContext> ---- -[TIP] -**Specifying the cache option inside XML** + -Camel supports specifying a value for the cache option both -inside the Spring as well as the Blueprint XML. - -== Using a Properties from the Registry - -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 xref:properties-component.adoc[Properties] component as -follows: - -[source,xml] ----- - <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. - -== Examples using properties component - -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. - -[source,java] ----- -// properties -cool.end=mock:result - -// route -from("direct:start").to("{{cool.end}}"); ----- - -You can also use placeholders as a part of the endpoint uri: - -[source,java] ----- -// properties -cool.foo=result - -// route -from("direct:start").to("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: - -[source,java] ----- -// properties -cool.foo=result -cool.concat=mock:{{cool.foo}} - -// route -from("direct:start").to("mock:{{cool.concat}}"); ----- - -Notice how `cool.concat` refer to another property. - -And you can use placeholders several times: - -[source,java] ----- -// 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: - -[source,java] ----- -template.sendBody("{{cool.start}}", "Hello World"); ----- - -== Example with xref:languages:simple-language.adoc[Simple] language - -The xref:languages:simple-language.adoc[Simple] language now also support using property -placeholders, for example in the route below: - -[source,java] ----- -// properties -cheese.quote=Camel rocks - -// route -from("direct:start") - .transform().simple("Hi ${body} do you think ${properties:cheese.quote}?"); ----- - -== Negate boolean value - -If a property placeholder is a boolean value, then it is possible to negate (reverse) the value by using `!` as prefix in the key. - -[source,java] ----- -// properties -integration.ftpEnabled=true - -// route -from("ftp:....").autoStartup("{{integration.ftpEnabled}}") - .to("kafka:cheese") - -from("jms:....").autoStartup("{{!integration.ftpEnabled}}") - .to("kafka:cheese") ----- - -In the example above then the FTP route or the JMS route should only be started. So if the FTP is enabled then JMS should be disable, and vise-versa. -We can do this be negating the `autoStartup` in the JMS route, by using `!integration.ftpEnabled` as the key. - == Additional property placeholder supported in Spring XML -The property placeholders is also supported in many of the Camel Spring -XML tags such as -`<package>, <packageScan>, <contextScan>, <jmxAgent>, <endpoint>, <routeBuilder>, -and the others. +The property placeholders is also supported in many of the Camel Spring XML tags such as `<package>, <packageScan>, <contextScan>, <jmxAgent>, <endpoint>, <routeBuilder>, and the others. The example below has property placeholder in the `<jmxAgent>` tag: @@ -352,8 +141,7 @@ The example below has property placeholder in the `<jmxAgent>` tag: </camelContext> ---- -You can also define property placeholders in the various attributes on -the `<camelContext>` tag such as `trace` as shown here: +You can also define property placeholders in the various attributes on the `<camelContext>` tag such as `trace` as shown here: [source,xml] ---- @@ -372,8 +160,7 @@ the `<camelContext>` tag such as `trace` as shown here: == Using JVM system properties or Environment variables as override or fallback values -The properties components supports using JVM system properties and also OS environment variables -as values which can either be used as override or fallback values. +The properties components supports using JVM system properties and also OS environment variables as values which can either be used as override or fallback values. The default mode is that both of them are in override mode, and they are check in the following order: @@ -388,445 +175,51 @@ The check stops at first found property value for the key. You can control these modes using the `systemPropertiesMode` and `environmentVariableMode` options on the properties component. -== Using property placeholders for any kind of attribute in the XML DSL - -In the example below we use the `prop` prefix for the namespace -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 - -[source] ----- -stop=true ----- - -== Using Blueprint property placeholder with Camel routes - -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: - -[source,xml] ----- -<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> ----- - -=== 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. - -=== About placeholder syntax - -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: - -[source,xml] ----- -<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"/> - - <!-- in the route we can use {{ }} placeholders which will lookup in blueprint --> - <route> - <from uri="direct:start"/> - <to uri="mock:foo"/> - <to uri="{{prefix.result}}"/> - </route> - </camelContext> -</blueprint> ----- - - -== 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: - -[source] ----- -location="blueprint:myblueprint.placeholder,classpath:myproperties.properties" ----- - -Each location is separated by comma. - -== Overriding Blueprint property placeholders outside CamelContext - -When using Blueprint property placeholder in the Blueprint XML file, you -can declare the properties directly in the XML file as shown below: - -[source,xml] ----- -<!-- blueprint property placeholders --> -<cm:property-placeholder persistent-id="my-placeholders" update-strategy="reload"> - <cm:default-properties> - <cm:property name="greeting" value="Hello"/> - <cm:property name="destination" value="mock:result"/> - </cm:default-properties> -</cm:property-placeholder> - -<!-- a bean that uses a blueprint property placeholder --> -<bean id="myCoolBean" class="org.apache.camel.test.blueprint.MyCoolBean"> - <property name="say" value="${greeting}"/> -</bean> - -<camelContext xmlns="http://camel.apache.org/schema/blueprint";> - - <route> - <from uri="direct:start"/> - <bean ref="myCoolBean" method="saySomething"/> - <to uri="{{destination}}"/> - </route> - -</camelContext> ----- - -Notice that we have a `<bean>` which refers to one of the properties. And -in the Camel route we refer to the other using the `{{` and `}}` notation. - -Now if you want to override these Blueprint properties from an unit -test, you can do this as shown below: - -[source,java] ----- -protected String useOverridePropertiesWithConfigAdmin(Dictionary props) { - // add the properties we want to override - props.put("greeting", "Bye"); - - // return the PID of the config-admin we are using in the blueprint xml file - return "my-placeholders"; -} ----- - -To do this we override and implement the -`useOverridePropertiesWithConfigAdmin` method. We can then put the -properties we want to override on the given props parameter. And the -return value *must* be the `persistence-id` of the -`<cm:property-placeholder>` tag, which you define in the blueprint XML -file. - -== Using .cfg or .properties file for Blueprint property placeholders - -When using Blueprint property placeholder in the Blueprint XML file, you -can declare the properties in a `.properties` or `.cfg` file. If you use -Apache ServieMix / Karaf then this container has a convention that it -loads the properties from a file in the etc directory with the naming -`etc/pid.cfg`, where `pid` is the `persistence-id`. - -For example in the blueprint XML file we have the -`persistence-id="stuff"`, which mean it will load the configuration file -as `etc/stuff.cfg`. - -Now if you want to unit test this blueprint XML file, then you can -override the `loadConfigAdminConfigurationFile` and tell Camel which -file to load as shown below: - -[source,java] ----- -@Override -protected String[] loadConfigAdminConfigurationFile() { - // String[0] = tell Camel the path of the .cfg file to use for OSGi ConfigAdmin in the blueprint XML file - // String[1] = tell Camel the persistence-id of the cm:property-placeholder in the blueprint XML file - return new String[]{"src/test/resources/etc/stuff.cfg", "stuff"}; -} ----- - -Notice that this method requires to return a `String[]` with 2 values. The -1st value is the path for the configuration file to load. -The 2nd value is the `persistence-id` of the `<cm:property-placeholder>` -tag. - -The `stuff.cfg` file is just a plain properties file with the property -placeholders such as: - -[source] ----- -== this is a comment -greeting=Bye ----- - -== Using .cfg file and overriding properties for Blueprint property placeholders - -You can do both as well. Here is a complete example. First we have the -Blueprint XML file: - -And in the unit test class we do as follows: - -And the `etc/stuff.cfg` configuration file contains - -[source] ----- -greeting=Bye -echo=Yay -destination=mock:result ----- - -== Bridging Spring and Camel property placeholders - -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: - -[source,xml] ----- - <!-- bridge spring property placeholder with Camel --> - <!-- you must NOT use the <context:property-placeholder at the same time, only this bridge bean --> - <bean id="bridgePropertyPlaceholder" class="org.apache.camel.spring.spi.BridgePropertyPlaceholderConfigurer"> - <property name="location" value="classpath:org/apache/camel/component/properties/cheese.properties"/> - </bean> ----- - -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: - -[source,xml] ----- - <!-- a bean that uses Spring property placeholder --> - <!-- the ${hi} is a spring property placeholder --> - <bean id="hello" class="org.apache.camel.component.properties.HelloBean"> - <property name="greeting" value="${hi}"/> - </bean> - - <camelContext xmlns="http://camel.apache.org/schema/spring";> - <!-- in this route we use Camels property placeholder {{ }} style --> - <route> - <from uri="direct:{{cool.bar}}"/> - <bean ref="hello"/> - <to uri="{{cool.end}}"/> - </route> - </camelContext> ----- - -Notice how the hello bean is using pure Spring property placeholders -using the `${ }` notation. And in the Camel routes we use the Camel -placeholder notation with `{{` and `}}`. - -== Clashing Spring property placeholders with Camels Simple language - -Take notice when using Spring bridging placeholder then the spring `${ }` -syntax clashes with the xref:languages:simple-language.adoc[Simple] in Camel, and therefore -take care. For example: - -[source,xml] ----- -<setHeader name="Exchange.FILE_NAME"> - <simple>{{file.rootdir}}/${in.header.CamelFileName}</simple> -</setHeader> ----- - -clashes with Spring property placeholders, and you should use `$simple{ }` -to indicate using the xref:languages:simple-language.adoc[Simple] language in Camel. - -[source,xml] ----- -<setHeader name="Exchange.FILE_NAME"> - <simple>{{file.rootdir}}/$simple{in.header.CamelFileName}</simple> -</setHeader> ----- - -An alternative is to configure the `PropertyPlaceholderConfigurer` with -`ignoreUnresolvablePlaceholders` option to `true`. - -== Overriding properties from Camel test kit - -When Testing with Camel and using the -xref:properties-component.adoc[Properties] component, you may want to be able to -provide the properties to be used from directly within the unit test -source code. + -Camel test kits, eg `CamelTestSupport` class offers the following methods - -* `useOverridePropertiesWithPropertiesComponent` -* `ignoreMissingLocationWithPropertiesComponent` - -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. - -== Using @PropertyInject - -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: - -[source,java] ----- -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: - -[source,java] ----- -@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: - -[source,java] ----- -@PropertyInject(value = "myTimeout", defaultValue = "5000") -private int timeout; ----- == Using out of the box functions -The xref:properties-component.adoc[Properties] component includes the following -functions out of the box +The xref:properties-component.adoc[Properties] component includes the following functions out of the box: * `env` - A function to lookup the property from OS environment variables -* `sys` - A function to lookup the property from Java JVM system -properties -* `service` - A function to lookup the property from OS environment -variables using the service naming idiom -* `service.name` - A function to lookup the -property from OS environment variables using the service naming idiom -returning the hostname part only -* `service.port` - A function to lookup the -property from OS environment variables using the service naming idiom -returning the port part only - -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: +* `sys` - A function to lookup the property from Java JVM system properties +* `service` - A function to lookup the property from OS environment variables using the service naming idiom +* `service.name` - A function to lookup the property from OS environment variables using the service naming idiom returning the hostname part only +* `service.port` - A function to lookup the property from OS environment variables using the service naming idiom returning the port part only + +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: [source,xml] ---- <camelContext xmlns="http://camel.apache.org/schema/blueprint";> <route> <from uri="direct:start"/> - <to uri="{`{env:SOMENAME}`}"/> - <to uri="{`{sys:MyJvmPropertyName}`}"/> + <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. +You can use default values as well, so if the property does not exist, you can define a default value as shown below, where the default value is a `log:foo` and `log:bar` value. [source,xml] ---- <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}`}"/> + <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` +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` * __NAME__**_SERVICE_HOST** * __NAME__**_SERVICE_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 +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 [source] ---- @@ -834,9 +227,7 @@ 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: +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: [source,xml] ---- @@ -848,8 +239,7 @@ the HTTP component to make the HTTP call: </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 +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 [source,xml] ---- @@ -863,40 +253,33 @@ example to call a service on localhost, maybe for unit testing etc == Using custom functions (advanced) -The xref:properties-component.adoc[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 +The xref:properties-component.adoc[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 [source,xml] ---- -<bean id="beerFunction" class="MyBeerFunction"/> +<beans> + <bean id="beerFunction" class="MyBeerFunction"/> -<camelContext xmlns="http://camel.apache.org/schema/blueprint";> - <propertyPlaceholder id="properties"> - <propertiesFunction ref="beerFunction"/> - </propertyPlaceholder> + <camelContext> + <propertyPlaceholder id="properties"> + <propertiesFunction ref="beerFunction"/> + </propertyPlaceholder> - <route> - <from uri="direct:start"/> - <to uri="{`{beer:FOO}`}"/> - <to uri="{`{beer:BAR}`}"/> - </route> -</camelContext> + <route> + <from uri="direct:start"/> + <to uri="{{beer:FOO}}"/> + <to uri="{{beer:BAR}}"/> + </route> + </camelContext> +</beans> ---- -[NOTE] -==== -The location attribute (on propertyPlaceholder tag) is not mandatory -==== - 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`. +`<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: @@ -916,48 +299,73 @@ public static final class MyBeerFunction implements PropertiesFunction { } ---- -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. +The function must implement the `org.apache.camel.spi.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: [source,java] ---- -PropertiesComponent pc = (org.apache.camel.componennt.properties.PropertiesComponent) context.getPropertiesComponent(); +PropertiesComponent pc = context.getPropertiesComponent(); pc.addFunction(new MyBeerFunction()); ---- +== PropertySource + +The regular `PropertySource` will lookup the property on-demand, for example to lookup values from a backend source such as a database or HashiCorp Vault etc. + +=== LoadablePropertySource + +A `PropertySource` can define that it supports loading all its properties from the source at once, for example from file system. +This allows Camel properties component to load these properties at once during startup. -== Using 3rd-party properties sources +=== Using 3rd-party PropertySource The properties component allows to plugin 3rd party sources to load and lookup properties via the `PropertySource` -API from camel-api. For example the `camel-microprofile-config` component is implemented using this. -The 3rd-party `PropertySource` can automatic be discoverd from classpath when Camel is starting up. -This is done by include the file `META-INF/services/org/apache/camel/property-source-factory` file -which refers to the fully qualified class name of the `PropertySource` implementation. -See the `camel-microprofile-config` for an example. +API from camel-api. + +For example the `camel-microprofile-config` component is implemented using this. +The 3rd-party `PropertySource` can automatic be discovered from classpath when Camel is starting up. +This is done by include the file `META-INF/services/org/apache/camel/property-source-factory` file which refers to the fully qualified class name of the `PropertySource` implementation. + +See xref:components:others:microprofile-config.adoc[MicroProfile Config] component as an example. -You can also register 3rd-part property sources via Java API +You can also register 3rd-party property sources via Java API: [source,java] ---- -PropertiesComponent pc = ... +PropertiesComponent pc = context.getPropertiesComponent(); pc.addPropertySource(myPropertySource); ---- -=== LoadablePropertySource - -A `PropertySource` can define that it supports loading all its properties from the source at once, -for example from file system. This allows Camel properties component to load these properties at once -during startup. -=== PropertySource - -The regular `PropertySource` will lookup the property on-demand, for example to lookup -values from a backend source such as a database or HashiCorp Vault etc. +== Spring Boot Auto-Configuration +The component supports 10 options, which are listed below. +[width="100%",cols="2,5,^1,2",options="header"] +|=== +| Name | Description | Default | Type +| *camel.component.properties.auto-discover-properties-sources* | Whether to automatically discovery instances of PropertiesSource from registry and service factory. | true | Boolean +| *camel.component.properties.default-fallback-enabled* | If false, the component does not attempt to find a default for the key by looking after the colon separator. | true | Boolean +| *camel.component.properties.encoding* | Encoding to use when loading properties file from the file system or classpath. +If no encoding has been set, then the properties files is loaded using ISO-8859-1 encoding (latin-1) as documented by java.util.Properties#load(java.io.InputStream) | | String +| *camel.component.properties.environment-variable-mode* | Sets the OS environment variables mode (0 = never, 1 = fallback, 2 = override). +The default mode (override) is to use OS environment variables if present, and override any existing properties. +OS environment variable mode is checked before JVM system property mode | 2 | Integer +| *camel.component.properties.ignore-missing-location* | Whether to silently ignore if a location cannot be located, such as a properties file not found. | false | Boolean +| *camel.component.properties.initial-properties* | Sets initial properties which will be used before any locations are resolved. +The option is a java.util.Properties type. | | String +| *camel.component.properties.location* | A list of locations to load properties. +You can use comma to separate multiple locations. +This option will override any default locations and only use the locations from this option. | | String +| *camel.component.properties.override-properties* | Sets a special list of override properties that take precedence and will use first, if a property exist. +The option is a java.util.Properties type. | | String +| *camel.component.properties.properties-parser* | To use a custom PropertiesParser. +The option is a org.apache.camel.component.properties.PropertiesParser type. | | String +| *camel.component.properties.system-properties-mode* | Sets the JVM system property mode (0 = never, 1 = fallback, 2 = override). +The default mode (override) is to use system properties if present, and override any existing properties. +OS environment variable mode is checked before JVM system property mode | 2 | Integer +|===
