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Chapter 3. Getting started with Camel K

This chapter explains how to set up your development environment and how to develop and deploy simple Camel K integrations written in Java, XML, and YAML. It also shows how to use the kamel command line to manage Camel K integrations at runtime. For example, this includes running, describing, logging, and deleting integrations,

3.1. Setting up your Camel K development environment

You must set up your environment with the recommended development tooling before you can automatically deploy the Camel K quick start tutorials. This section explains how to install the recommended Visual Studio (VS) Code IDE and the extensions that it provides for Camel K.

Note

VS Code is recommended for ease of use and the best developer experience of Camel K. This includes automatic completion of Camel DSL code and Camel K traits, and automatic execution of tutorial commands. However, you can manually enter your code and tutorial commands using your chosen IDE instead of VS Code.

Prerequisites

You must have access to an OpenShift cluster on which the Camel K Operator and OpenShift Serverless Operator are installed:
- Section 2.1, “Installing Camel K from the OpenShift OperatorHub”
- Section 2.2, “Installing OpenShift Serverless from the OperatorHub”
Section 2.3, “Installing the Camel K and OpenShift command line tools”

Procedure

Install VS Code on your development platform. For example, on Red Hat Enterprise Linux:

Install the required key and repository:

$ sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc
$ sudo sh -c 'echo -e "[code]\nname=Visual Studio Code\nbaseurl=https://packages.microsoft.com/yumrepos/vscode\nenabled=1\ngpgcheck=1\ngpgkey=https://packages.microsoft.com/keys/microsoft.asc" > /etc/yum.repos.d/vscode.repo'

Update the cache and install the VS Code package:
```
$ yum check-update
$ sudo yum install code
```
For details on installing on other platforms, see the VS Code installation documentation.

Enter the code command to launch the VS Code editor. For more details, see the VS Code command line documentation.
Install the VS Code Camel Extension Pack, which includes the extensions required for Camel K. For example, in VS Code:
1. In the left navigation bar, click Extensions.
2. In the search box, enter Apache Camel.
3. Select the Extension Pack for Apache Camel by Red Hat, and click Install.
  For more details, see the instructions for the Extension Pack for Apache Camel by Red Hat.
Install the VS Code Didact extension, which you can use to automatically run quick start tutorial commands by clicking links in the tutorial. For example, in VS Code:
1. In the left navigation bar, click Extensions.
2. In the search box, enter Didact.
3. Select the extension, and click Install.
  For more details, see the instructions for the Didact extension.

Additional resources

3.2. Developing Camel K integrations in Java

This section shows how to develop a simple Camel K integration in Java DSL. Writing an integration in Java to be deployed using Camel K is the same as defining your routing rules in Camel. However, you do not need to build and package the integration as a JAR when using Camel K.

You can use any Camel component directly in your integration routes. Camel K automatically handles the dependency management and imports all the required libraries from the Camel catalog using code inspection.

Prerequisites

Section 3.1, “Setting up your Camel K development environment”

Procedure

Enter the kamel init command to generate a simple Java integration file. For example:
```
$ kamel init HelloCamelK.java
```

Open the generated integration file in your IDE and edit as appropriate. For example, the HelloCamelK.java integration automatically includes the Camel timer and log components to help you get started:

// camel-k: language=java

import org.apache.camel.builder.RouteBuilder;

public class HelloCamelK extends RouteBuilder {
  @Override
  public void configure() throws Exception {

      // Write your routes here, for example:
      from("timer:java?period=1s")
        .routeId("java")
        .setBody()
          .simple("Hello Camel K from ${routeId}")
        .to("log:info");

  }
}

Next steps

Section 3.5, “Running Camel K integrations”

3.3. Developing Camel K integrations in XML

This section explains how to develop a simple Camel K integration in classic XML DSL. Writing an integration in XML to be deployed using Camel K is the same as defining your routing rules in Camel.

Prerequisites

Section 3.1, “Setting up your Camel K development environment”

Procedure

Enter the kamel init command to generate a simple XML integration file. For example:
```
$ kamel init hello-camel-k.xml
```

Open the generated integration file in your IDE and edit as appropriate. For example, the hello-camel-k.xml integration automatically includes the Camel timer and log components to help you get started:

<?xml version="1.0" encoding="UTF-8"?>
<!-- camel-k: language=xml -->

<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="http://camel.apache.org/schema/spring"
        xsi:schemaLocation="
            http://camel.apache.org/schema/spring
            http://camel.apache.org/schema/spring/camel-spring.xsd">

    <!-- Write your routes here, for example: -->
    <route id="xml">
        <from uri="timer:xml?period=1s"/>
        <setBody>
            <simple>Hello Camel K from ${routeId}</simple>
        </setBody>
        <to uri="log:info"/>
    </route>

</routes>

Next steps

Section 3.5, “Running Camel K integrations”

3.4. Developing Camel K integrations in YAML

This section explains how to develop a simple Camel K integration in YAML DSL. Writing an integration in YAML to be deployed using Camel K is the same as defining your routing rules in Camel.

Prerequisites

Section 3.1, “Setting up your Camel K development environment”

Procedure

Enter the kamel init command to generate a simple XML integration file. For example:
```
$ kamel init hello.camelk.yaml
```
Open the generated integration file in your IDE and edit as appropriate. For example, the hello.camelk.yaml integration automatically includes the Camel timer and log components to help you get started:
```
# camel-k: language=yaml

# Write your routes here, for example:
- from:
    uri: "timer:yaml"
    parameters:
      period: "1s"
    steps:
      - set-body:
          constant: "Hello Camel K from yaml"
      - to: "log:info"
```
Important
Integrations written in YAML must have a file name with the pattern *.camelk.yaml or a first line of # camel-k: language=yaml.

Additional resources

Writing Apache Camel integrations in YAML

3.5. Running Camel K integrations

You can run Camel K integrations in the cloud on your OpenShift cluster from the command line using the kamel run command.

Prerequisites

Section 3.1, “Setting up your Camel K development environment”.
You must already have a Camel integration written in Java, XML, or YAML DSL.

Procedure

Log into your OpenShift cluster using the oc client tool, for example:

$ oc login --token=my-token --server=https://my-cluster.example.com:6443

Ensure that the Camel K Operator is running, for example:

$ oc get pod
NAME                               READY   STATUS    RESTARTS   AGE
camel-k-operator-86b8d94b4-pk7d6   1/1     Running   0          6m28s

Enter the kamel run command to run your integration in the cloud on OpenShift. For example:

Java example

$ kamel run HelloCamelK.java
integration "hello-camel-k" created

XML example

$ kamel run hello-camel-k.xml
integration "hello-camel-k" created

YAML example

$ kamel run hello.camelk.yaml
integration "hello" created

Enter the kamel get command to check the status of the integration:
```
$ kamel get
NAME       PHASE           KIT
hello      Building Kit    kit-bq666mjej725sk8sn12g
```
When the integration runs for the first time, Camel K builds the integration kit for the container image, which downloads all the required Camel modules and adds them to the image classpath.

Enter kamel get again to verify that the integration is running:

$ kamel get
NAME       PHASE   KIT
hello      Running kit-bq666mjej725sk8sn12g

Enter the kamel log command to print the log to stdout:

$ kamel log hello
[1] 2020-04-11 14:26:43.449 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.PropertiesFunctionsConfigurer@5223e5ee executed in phase Starting
[1] 2020-04-11 14:26:43.457 INFO  [main] RuntimeSupport - Looking up loader for language: yaml
[1] 2020-04-11 14:26:43.655 INFO  [main] RuntimeSupport - Found loader org.apache.camel.k.loader.yaml.YamlSourceLoader@1224144a for language yaml from service definition
[1] 2020-04-11 14:26:43.658 INFO  [main] RoutesConfigurer - Loading routes from: file:/etc/camel/sources/i-source-000/hello.camelk.yaml?language=yaml
[1] 2020-04-11 14:26:43.658 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.RoutesConfigurer@36c88a32 executed in phase ConfigureRoutes
[1] 2020-04-11 14:26:43.661 INFO  [main] BaseMainSupport - Using properties from: file:/etc/camel/conf/application.properties
[1] 2020-04-11 14:26:43.878 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.ContextConfigurer@65466a6a executed in phase ConfigureContext
[1] 2020-04-11 14:26:43.879 INFO  [main] DefaultCamelContext - Apache Camel 3.0.1 (CamelContext: camel-k) is starting
[1] 2020-04-11 14:26:43.880 INFO  [main] DefaultManagementStrategy - JMX is disabled
[1] 2020-04-11 14:26:44.147 INFO  [main] DefaultCamelContext - StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
[1] 2020-04-11 14:26:44.157 INFO  [main] DefaultCamelContext - Route: route1 started and consuming from: timer://yaml?period=1s
[1] 2020-04-11 14:26:44.161 INFO  [main] DefaultCamelContext - Total 1 routes, of which 1 are started
[1] 2020-04-11 14:26:44.162 INFO  [main] DefaultCamelContext - Apache Camel 3.0.1 (CamelContext: camel-k) started in 0.283 seconds
[1] 2020-04-11 14:26:44.163 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.RoutesDumper@1c93084c executed in phase Started
[1] 2020-04-11 14:26:45.183 INFO  [Camel (camel-k) thread #1 - timer://yaml] info - Exchange[ExchangePattern: InOnly, BodyType: String, Body: Hello Camel K from yaml]
...

Press Ctrl-C to terminate logging in the terminal.

Additional resources

For more details on the kamel run command, enter kamel run --help
For faster deployment turnaround times, see Section 3.6, “Running Camel K integrations in development mode”
For details of development tools to run integrations, see VS Code Tooling for Apache Camel K by Red Hat
See also Section 5.1, “Managing Camel K integrations”

3.6. Running Camel K integrations in development mode

You can run Camel K integrations in development mode on your OpenShift cluster from the command line. Using development mode, you can iterate quickly on integrations in development and get fast feedback on your code.

When you specify the kamel run command with the --dev option, this deploys the integration in the cloud immediately and shows the integration logs in the terminal. You can then change the code and see the changes automatically applied instantly to the remote integration Pod on OpenShift. The terminal automatically displays all redeployments of the remote integration in the cloud.

Note

The artifacts generated by Camel K in development mode are identical to those that you run in production. The purpose of development mode is faster development.

Prerequisites

Section 3.1, “Setting up your Camel K development environment”.
You must already have a Camel integration written in Java, XML, or YAML DSL.

Procedure

Log into your OpenShift cluster using the oc client tool, for example:

$ oc login --token=my-token --server=https://my-cluster.example.com:6443

Ensure that the Camel K Operator is running, for example:

$ oc get pod
NAME                               READY   STATUS    RESTARTS   AGE
camel-k-operator-86b8d94b4-pk7d6   1/1     Running   0          6m28s

Enter the kamel run command with --dev to run your integration in development mode on OpenShift in the cloud. The following shows a simple Java example:

$ kamel run HelloCamelK.java --dev
integration "hello-camel-k" created
Progress: integration "hello-camel-k" in phase Initialization
Progress: integration "hello-camel-k" in phase Building Kit
Progress: integration "hello-camel-k" in phase Deploying
Progress: integration "hello-camel-k" in phase Running
IntegrationPlatformAvailable for Integration hello-camel-k: camel-k
Integration hello-camel-k in phase Initialization
No IntegrationKitAvailable for Integration hello-camel-k: creating a new integration kit
Integration hello-camel-k in phase Building Kit
IntegrationKitAvailable for Integration hello-camel-k: kit-bq8t5cudeam3u3sj13tg
Integration hello-camel-k in phase Deploying
No CronJobAvailable for Integration hello-camel-k: different controller strategy used (deployment)
DeploymentAvailable for Integration hello-camel-k: deployment name is hello-camel-k
No ServiceAvailable for Integration hello-camel-k: no http service required
No ExposureAvailable for Integration hello-camel-k: no target service found
Integration hello-camel-k in phase Running
[2] Monitoring pod hello-camel-k-866ccb5976-sjh8x[1] Monitoring pod hello-camel-k-866ccb5976-l288p[2] 2020-04-11 14:44:53.691 INFO  [main] ApplicationRuntime - Add listener: org.apache.camel.k.listener.ContextConfigurer@159f197
[2] 2020-04-11 14:44:53.694 INFO  [main] ApplicationRuntime - Add listener: org.apache.camel.k.listener.RoutesConfigurer@1f0f1111
[2] 2020-04-11 14:44:53.695 INFO  [main] ApplicationRuntime - Add listener: org.apache.camel.k.listener.RoutesDumper@6e0dec4a
[2] 2020-04-11 14:44:53.695 INFO  [main] ApplicationRuntime - Add listener: org.apache.camel.k.listener.PropertiesFunctionsConfigurer@794cb805
[2] 2020-04-11 14:44:53.712 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.PropertiesFunctionsConfigurer@794cb805 executed in phase Starting
[2] 2020-04-11 14:44:53.721 INFO  [main] RuntimeSupport - Looking up loader for language: java
[2] 2020-04-11 14:44:53.723 INFO  [main] RuntimeSupport - Found loader org.apache.camel.k.loader.java.JavaSourceLoader@3911c2a7 for language java from service definition
[2] 2020-04-11 14:44:54.220 INFO  [main] RoutesConfigurer - Loading routes from: file:/etc/camel/sources/i-source-000/HelloCamelK.java?language=java
[2] 2020-04-11 14:44:54.220 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.RoutesConfigurer@1f0f1111 executed in phase ConfigureRoutes
[2] 2020-04-11 14:44:54.224 INFO  [main] BaseMainSupport - Using properties from: file:/etc/camel/conf/application.properties
[2] 2020-04-11 14:44:54.385 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.ContextConfigurer@159f197 executed in phase ConfigureContext
[2] 2020-04-11 14:44:54.386 INFO  [main] DefaultCamelContext - Apache Camel 3.0.1 (CamelContext: camel-k) is starting
[2] 2020-04-11 14:44:54.387 INFO  [main] DefaultManagementStrategy - JMX is disabled
[2] 2020-04-11 14:44:54.630 INFO  [main] DefaultCamelContext - StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
[2] 2020-04-11 14:44:54.639 INFO  [main] DefaultCamelContext - Route: java started and consuming from: timer://java?period=1s
[2] 2020-04-11 14:44:54.643 INFO  [main] DefaultCamelContext - Total 1 routes, of which 1 are started
[2] 2020-04-11 14:44:54.643 INFO  [main] DefaultCamelContext - Apache Camel 3.0.1 (CamelContext: camel-k) started in 0.258 seconds
[2] 2020-04-11 14:44:54.644 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.RoutesDumper@6e0dec4a executed in phase Started
[2] 2020-04-11 14:44:55.671 INFO  [Camel (camel-k) thread #1 - timer://java] info - Exchange[ExchangePattern: InOnly, BodyType: String, Body: Hello Camel K from java]
...

Edit the content of your integration DSL file, save your changes, and see the changes displayed instantly in the terminal. For example:

...
integration "hello-camel-k" updated
...
[3] 2020-04-11 14:45:06.792 INFO  [main] DefaultCamelContext - Route: java started and consuming from: timer://java?period=1s
[3] 2020-04-11 14:45:06.795 INFO  [main] DefaultCamelContext - Total 1 routes, of which 1 are started
[3] 2020-04-11 14:45:06.796 INFO  [main] DefaultCamelContext - Apache Camel 3.0.1 (CamelContext: camel-k) started in 0.323 seconds
[3] 2020-04-11 14:45:06.796 INFO  [main] ApplicationRuntime - Listener org.apache.camel.k.listener.RoutesDumper@6e0dec4a executed in phase Started
[3] 2020-04-11 14:45:07.826 INFO  [Camel (camel-k) thread #1 - timer://java] info - Exchange[ExchangePattern: InOnly, BodyType: String, Body: Ciao Camel K from java]
...

Press Ctrl-C to terminate logging in the terminal.

Additional resources

For more details on the kamel run command, enter kamel run --help
For details of development tools to run integrations, see VS Code Tooling for Apache Camel K by Red Hat
Section 5.1, “Managing Camel K integrations”
Section 7.6, “Configuring Camel K integration dependencies”

3.7. Running Camel K integrations using modeline

You can use the Camel K modeline to specify multiple configuration options in a Camel K integration source file, which are executed at runtime. This creates efficiencies by saving you the time of re-entering multiple command line options and helps to prevent input errors.

The following example shows a modeline entry from a Java integration file that configures traits for Prometheus monitoring and 3scale API Management, and includes a dependency on an external Maven library:

// camel-k: language=java trait=prometheus.enabled=true trait=3scale.enabled=true dependency=mvn:org.my/app:1.0

Prerequisites

Section 3.1, “Setting up your Camel K development environment”.
You must already have a Camel integration written in Java, XML, or YAML DSL.

Procedure

Add a Camel K modeline entry to your integration file. For example:

Hello.java

// camel-k: language=java trait=prometheus.enabled=true trait=3scale.enabled=true dependency=mvn:org.my/application:1.0 1

import org.apache.camel.builder.RouteBuilder;

public class Hello extends RouteBuilder {
  @Override
  public void configure() throws Exception {

      from("timer:java?period=1000")
        .bean(org.my.BusinessLogic) 2
        .log("${body}");

  }
}

1: The modeline entry enables monitoring in Prometheus, API management with 3scale, and specifies a dependency on an external Maven library.
2: This bean uses a business logic class from the external Maven library configured in the modeline.

Enter the following command to run the integration:

$ kamel run Hello.java
Modeline options have been loaded from source files
Full command: kamel run Hello.java --trait=prometheus.enabled=true --dependency mvn:org.my/application:1.0

The kamel run command outputs any modeline options specified in the integration.

Additional resources

Section 9.2, “Camel K modeline options”
For details of development tools to run modeline integrations, see Introducing IDE support for Apache Camel K Modeline.

이 콘텐츠는 선택한 언어로 제공되지 않습니다.

Chapter 3. Getting started with Camel K

3.1. Setting up your Camel K development environment

3.2. Developing Camel K integrations in Java

3.3. Developing Camel K integrations in XML

3.4. Developing Camel K integrations in YAML

3.5. Running Camel K integrations

3.6. Running Camel K integrations in development mode

3.7. Running Camel K integrations using modeline

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