Karaf + Camel + Maven + Docker - maven

Question

I am new to Karaf and Camel and I'm trying to deploy custom camel routes (java) and I'm facing a lot of problems at the time of deploying the camel bundle (.jar) in the hot deploy directory.
What I got so far:
Apache Karaf 4.3.1 running in docker container
Bundle .jar with the java defined route
My idea is to have a /deploy directory mapped to the karaf container so any .jar that's added to that directory is deployed (or maybe build a new image for karaf).
When I tried to add my current bundle to the directory I got the following error message:
20:19:32.490 INFO [fileinstall-/opt/karaf/deploy] Installing bundle org.apache.karaf.examples.karaf-camel-example-java / 4.3.1
20:19:32.535 WARN [fileinstall-/opt/karaf/deploy] Error while starting bundle: file:/opt/karaf/deploy/karaf-camel-example-java-4.3.1.jar
org.osgi.framework.BundleException: Unable to resolve org.apache.karaf.examples.karaf-camel-example-java [111](R 111.0): missing requirement [org.apache.karaf.examples.karaf-camel-example-java [111](R 111.0)] osgi.wiring.package; (&(osgi.wiring.package=org.apache.camel)(version>=3.6.0)(!(version>=4.0.0))) Unresolved requirements: [[org.apache.karaf.examples.karaf-camel-example-java [111](R 111.0)] osgi.wiring.package; (&(osgi.wiring.package=org.apache.camel)(version>=3.6.0)(!(version>=4.0.0)))]
at org.apache.felix.framework.Felix.resolveBundleRevision(Felix.java:4368) ~[?:?]
at org.apache.felix.framework.Felix.startBundle(Felix.java:2281) ~[?:?]
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:998) ~[?:?]
at org.apache.felix.fileinstall.internal.DirectoryWatcher.startBundle(DirectoryWatcher.java:1260) [!/:3.6.8]
at org.apache.felix.fileinstall.internal.DirectoryWatcher.startBundles(DirectoryWatcher.java:1233) [!/:3.6.8]
at org.apache.felix.fileinstall.internal.DirectoryWatcher.doProcess(DirectoryWatcher.java:520) [!/:3.6.8]
at org.apache.felix.fileinstall.internal.DirectoryWatcher.process(DirectoryWatcher.java:365) [!/:3.6.8]
at org.apache.felix.fileinstall.internal.DirectoryWatcher.run(DirectoryWatcher.java:316) [!/:3.6.8]
I think this can be solve with a maven bundle "wrap" but I'm not sure if this is correct, and if so, how should I wrap the bundle?
Thank you for reading :D

Answer 1

A bit late but hope this helps someone as I've fiddled with this setup quite a bit for the past year while exploring OSGi, Karaf, Camel and Docker.
If you want to do local development with karaf you can actually map your maven repository to the container which can make installing bundles and features quite a bit easier.
Example Docker compose for Karaf
Here's a docker-compose for karaf 4.2.11 but you can probably change it to 4.3.1 without any problems. (add :z on volumes if using SELinux)
version: "2.4"
services:
karaf-runtime:
container_name: karaf
image: apache/karaf:4.2.11
ports:
- 8101:8101
- 8181:8181
- 1098:1098
volumes:
- ./karaf/etc:/opt/apache-karaf/etc
- ./karaf/deploy:/opt/apache-karaf/deploy
- karaf-data:/opt/apache-karaf/data
- ~/.m2:/root/.m2
- karaf-history:/root/.karaf
command: [ karaf, server ]
volumes:
karaf-data:
karaf-history:
Just save it to a empty folder somewhere as docker-compose.yml. Create folder named karaf to the folder and then fetch the default configurations from karaf using couple docker commands:
# Start detached karaf container with name karaf
docker run --name karaf -d apache/karaf:4.2.11
# copy files from container to host-system
docker cp karaf:opt/apache-karaf/etc ./karaf/
# stop the container
docker stop karaf
Setting karafs etc folder as shared volume makes it easy to tweak and share the configurations through version control for other developers.
To start Apache karaf with docker compose you can use following commands:
# Start
docker compose up -d
docker-compose up -d
# Stop
docker compose down
docker-compose down
# note: docker compose = newer version of docker-compose command
Creating bundles
Easy way to create bundles is to use one of the official archetypes karaf-bundle-archetype or karaf-blueprint-archetype when creating the project.
For projects using Apache Camel it is generally easier to use karaf-blueprint-archetype. With it you configure the CamelContext in the xml blueprint file found in projects resources/OSGI-INF/blueprint/ folder.
Example:
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0">
<bean id="ExampleRoute" class="com.example.ExampleRouteBuilder" />
<camelContext id="ExampleContext" xmlns="http://camel.apache.org/schema/blueprint">
<routeBuilder ref="ExampleRoute" />
</camelContext>
</blueprint>
With ~/.m2:/root/.m2 shared volume you can just package the project using mvn clean install to your local maven repository which you can then use in karaf to install the bundle using bundle:install mvn:groupId/artifactId/version
If you want to use deploy folder you can copy artifacts to container using docker cp ./target/exampleBundle.jar karaf:/opt/apache-karaf/deploy
Adding camel feature to karaf
As for camel you can follow the official guide on how to add camel feature repository and the features you need.
But the steps are basically:
# Add camel feature repo
feature:repo-add camel <version>
# Install camel feature
feature:install camel
# List available camel features for install
feature:list | grep camel
# Install camel features you need
feature:install <feature-name>
Missing requirements
When installing bundles often encounter missing requirement exception that tells you that package that the bundle depends on is missing from karaf which means you'll have to install bundle or feature that exports the said package.
These messages are usually best read starting from the end:
(osgi.wiring.package=org.apache.camel)(version>=3.6.0)(!(version>=4.0.0)
The above tells you that karaf installation doesn't have camel installed. OSGi bundles expect OSGi framework/runtime to satisfy their dependencies which is quite a bit different from say standalone SpringBoot projects.
Shared volumes and new files
When it comes to sharing config files or karaf deploy folder it's good to know that Docker has some issues related to new files in shared volumes. If new file is added/created using host-systems file-system there's chance that karaf will not detect these files or changes made to them.
It's generally better to use docker cp path/to/file/on/host karaf:/path/to/folder/on/container to deploy new files to container even if its shared volume.
otherwise you might have to shell in to the container and make copy of the file in question and