I have a c++ application that uses log4cxx for logging. log4cxx configuration will be done via XML file where the logging level and different loggers can be enabled and disabled. with installation running in VM it was easy to make the necessary modifications as needed by getting into VM and changing the XML file manually. but now we are going to run the application as a docker image which will run in the cloud, so the question is how to make modifications around the logger level as and when needed. I did try to search for this before asking here, but the solutions which are mentioned are java based, like spring boot admin, etc. which is not suitable here.
Related
There might be something I fundamentally misunderstand about Docker and containers, but... my scenario is as follows:
I have created an asp.net core application and a docker image for it.
The application requires some settings being added / removed at runtime
Also some dll plugins could be added and loaded by the application
These settings would normally be stored in appsettings.json and a few other settings files located in predefined relative path (e.g. ./PluginsConfig)
I don't know how many plugins will there be and how will they be configured
I didn't want to create any kind of UI in the web application for managing settings and uploading plugins - this was to be done on the backend (I need the solution simple and cheap)
I intend to deploy this application on a single server and the admin user would be able and responsible for setting the settings, uploading plugins etc. It's an internal productivity tool - there might be many instances of this application, but they would not be related at all.
The reason I want it in docker is to have it as self-contained as possible, with all the dependencies being there.
But how would I then allow accessing, adding and editing of the plugins and config files?
I'm sure there's a pattern that would allow this scenario.
What you are looking for are volumes and bind mounts. You can bind files or directories from a host machine to a container. Thus, host and container can share files.
Sample command (bind mount - (there are also other ways))
docker container run -v /path/on/host:/path/in/container image
Detailed information for volumes and bind mounts
I am containerizing an older Java web application with Docker. My Dockerfile pulls an official Tomcat image from Docker Hub (specifically, tomcat:8.5.49-jdk8-openjdk), copies my .WAR file into the webapps/ directory, and copies in some idiosyncratic configuration files and dependencies. It works.
Now I know that Tomcat comes out-of-the-box with a few directories under webapps/, including the "manager" app, and some others: ROOT, docs, examples, host-manager. I'm thinking I ought to delete these, lest one of my users access them, which might be a security risk and is unprofessional at the least.
Is it a best practice to delete those installed-by-default web apps from an official Tomcat image? Is there any downside to doing so? It seems logical to me, but a web search didn't turn up any expert opinion either way.
Every folder under webapps represents discrete Web Application contained within Tomcat Servlet Container after the server startup and deployment.
None of those web applications have any implicit or explicit correlation with either Catalina, Jasper or any other system component of Tomcat.
You should be quite OK to remove all those folders (apps) unless you need to have a Manager tool/application to manage your deployments and server. Even that can be installed again later on.
I am using the Spring Cloud Dataflow local server/deployer and upgrading from 1.1.4 to 1.2.3. I've found my stream configs such as value.deserializer are not being passed into the sink process correctly. I have tried both:
spring.cloud.stream.kafka.bindings.input.consumer.configuration.value.deserializer
spring.cloud.stream.kafka.binder.configuration.value.deserializer
Neither are working. There seem to be some significant changes with the local deployer. The entire argument list from both common configs and stream configs are visible from the process level now (e.g. using ps). However the stream configs not actually working. Configs work fine when running the Spring Cloud stream app locally.
Any idea what is happening or how I can troubleshoot this? Since Dataflow server is deploying the app it is difficult to debug.
What you've listed above aren't SCDF or Deployer specific overrides. They are Spring Cloud Stream properties, and from your description, it is unclear how you're passing it to the apps from SCDF.
Once after the applications are deployed (via SCDF), you can access the /env or /configprops endpoints to verify whether those overrides are applied. If they aren't applied, you can start with the application and its dependencies - compare it with the old stack. Hopefully, that will provide some insights.
If it is still unclear, you can share a sample that reproduces the problem.
I have a DockerFile that starts 2 processes in a single docker container using a jar file and a config file as an argument
java -jar process1.jar process1.cfg &
java -jar process2.jar process2.cfg
process1.cfg and process2.cfg are residing in mounted directories. Now whenever there is a change in any of the cfg files, I would need to restart the corresponding process for the new change to take effect. All these to be done programmatically using Java in a REST microservice that updates the config file and restarts the process. Any idea on how to go about it ?
The problem can be generically solved by your Java app starting a config change monitoring service/thread, which manages the actual business service/thread(s) by starting it in the beginning and restarting on any change (if the change actually needs a restart). File change monitoring is standard Java functionality. The solution does not need any REST, it is not bound to microservice architecture (although it is more sensible within it) and it is not limited by or to docker containers.
If you do not want any file-based configs, do the same, but the monitoring bit can be e.g. a vert.x-based web server listening for external REST requests supplying configs, on start or for any update. The rest remains the same.
In my current workplace we actually have a module that functions in exactly this way, it is deployed to a docker and uses both file system monitoring and vert.x web server for config changes.
You can even go further and make the monitoring bit start multiple instances internally if multiple configs need to be supported.
I sucessfully managed to complete with my Grail's new website and now i want to run it on my machine to acess it everywhere. I would like to know what is the best approach to do that, i'm a bit noob in what concerns servers and connections. Any help would be aprecciated.
Jm
You need a Java servlet container. The quickest and easiest approach is probably to use Jetty on a Linux system -- most will allow you to install it directly. This allows you run a deployed system from a "war" file. Basically, you would do something like:
grails war
To build the war file, and then copy that (it'll be created in the target directory, with a name based on your application name and version) to the webapps directory for Jetty. On my (Ubuntu) system, that's /var/lib/jetty/webapps/. If you name it root.war, it will serve URLs from the root of the server configuration (typically on port 8080), so http://myhost.mydomain:8080/ will be passed to your Grails application. You'll need to restart Jetty to pick up the new root.war file, e.g., sudo /etc/init.d/jetty restart
Jetty is not the most flexible or powerful servlet container, but it is probably the quickest way to get something up and running, and you can explore more powerful alternatives (Tomcat being an obvious one) as you have time.
Unless you need persistent storage in your app (e.g. end users uploading pictures, etc), you can use Cloud Foundry. It's free for now and makes deployment very easy.
http://blog.springsource.com/2011/04/12/one-step-deployment-with-grails-and-cloud-foundry/
I've been using is via STS and it works really well. There's just one really annoying thing and that's the fact that STS ends up doing a build war with every change.
There's a cloud foundry plugin that gives you command line deployment.
http://www.grails.org/plugin/cloud-foundry
Or there's a Cloud Foundry UI plugin that "provides a simple monitoring UI for your applications deployed to Cloud Foundry. It uses the same API as the Cloud Foundry plugin but is more convenient since runs in a web browser."
http://www.grails.org/plugin/cloud-foundry-ui