We are using k8s for deploying our application and it works awesome.But there is a small issue.We have moved from http layer communication to tcp layer.And the communication between different micro-services is through the service (k8s service) name and it works great but the developer can't test the same code locally as the service name will be resolved inside the cluster only.So here are some solutions that I have :-
1.Provided them a different name space where they can test the app with small changes.
The issue with this is that the developers use some break points and test some small changes in code and debug that will be hard by this method.
2.They can implement minikube in local but that doesn't sound good to even me.
3.They can run the container for ms locally and enter the ip of container in /etc/hosts corresponding to the k8s service name.In this the same code will work.
Any other better solutions are welcomed.
😔😔ðŸ˜ðŸ˜
Did you consider using spring boot profiles for this purpose? We are using it effectively for long across our teams. For this purpose, you'll have to extract the service(s) host as separate properties in application.yml (or application.properties) and use this host in rest of the properties as a variable. Following snippet explains this
application.yml
----------------
serviceA:
host: service-A-Name
api-one-endpoint: http://${serviceA.host}/api/v1/one
api-two-endpoint: http://${serviceA.host}/api/v1/two
api-three-endpoint: http://${serviceA.host}/api/v1/three
api-four-endpoint: http://${serviceA.host}/api/v1/four
In production (any hosted/managed environment for that matter), you provide appropriate value for spring property serviceA.host. In your use case, you'll be using this value AS-IS and provide k8s service name binding instead.
For local dev environment, you only need to override single property. For simple use case (say you need to override only single property), you can pass it as an agrument to your spring boot launcher (e.g. "--serviceA.host=localhost"). If you have many services (you likely do) even then you'll need to override well known few host name properties only. Using a dedicated dev profiles is much better in this case. Following example illustrate same scenario
application-dev.yml
-------------------
serviceA:
host: mylocalhost:9090
Then you use this profile in your eclipse/intellij launcher configuraiton for execution or debugging purpose by adding "--spring.profiles.active=dev" as and additional argument and spring boot will use updated host from dev profile. In fact combining these two approaches gives you even more flexibility for advance cases. If you agree on a common port convention across team then you can even check-in application-dev.yml for usage by everyone pretty much as-is.
spring boot profiles is much more powerful feature, I'll strongly recommend to go through it's documentation and few tutorial (like this one) to understand it fully and exploit it effectively for use cases like this one.
I have my application on production on some domain name ABC.com. In my code i am redirecting user to other page based upon on some action
response.sendRedirect(request.getServletContext().getContextPath() + "/time");
But by the above it get redirected to localhost:8080//time
but instead of this i want it to get redirected to ABC.com/time
How can i do this? A simple solution coming to my mind is that i should set some environment variable for production and instead of using
request.getServletContext().getContextPath()
, i will use environment variable value i.e. ABC.com
If you really need the domain under which your server can been reached, then the environment variable way is the only way that works all times (for example even if there is a proxy in front of your server...)
It seems to me that this should work with the domain that you want, provided that the application is operating from said domain. Right now you are probably using a development environment on your localhost, which means the servlet is operating on localhost:8080 and will also pass that back as it's path. When you deploy your application it should work.
If you need to redirect to the production version even though you are running in a development environment, you should hardcore the URL in a configuration variable of sorts. I prefer using .conf files and reading those at runtime since it allows you to alter their contents on the fly easily.
One minor thing that might cause issues is the double slashes. A path or URL will end in a slash so you don't have to append the second one. Simply doing + "time" should be enough.
I have a webservice that uses Java, REST, Jersey and runs on Tomcat8. The webservice requires access to a database. Depending on where we are in the process the we may be using a testdatabase, production database or something else. Ideally we would like to be able to set which database to use without requiring a code change and recompile.
The approach we have tried is to have a properties file defining the database parameters and use an environment variable to point to the file. This has proved troublesome, first we've had a hard time defining system properties on the Tomcat server that we can read from the application, also it seems like all the files will have to be defined on the classpath, i.e already configured ahead of time and part of the codebase.
This seems like fairly common scenario, so I'm sure there is a recommended way to handle situations like this?
Zack Macomber has a point here. Don't enable your app/service to look up its settings dynamically.
Make your build process dynamic instead.
Maven, Gradle and friends all provide simple ways to modify output depending on build parameters and or tasks/profiles.
In your code always link to the same file (name). The actual file will then be included based on your task and/or build environment. Test config for tests. Production config for production.
In many cases a complete recompilation is not necessary and will therefore be skipped (this depends on your tool, of course).
No code changes at all. Moreover the code will be dumb as hell as it does not need to know anything about context.
Especially when working on something with multiple people this approach provides the most stable long-term-solution. Customizable for those who need some special, local config and most important transparent for all who don't need or don't want to know about runtime environment requirements!
We have a similar case. We have created a second web service on the same endpoint (/admin) which we call to set a few configuration parameters. We also have a DB for persisting the configuration once set. To make life easier, we also created a simple UI to set these values. The user configures the values in the UI, the UI calls the /admin web service, and the /admin service sets the configuration in memory (as properties) as well as in the DB. The main web service uses the properties as dynamic configuration.
Note: we use JWT based authorization to prevent unauthorized access to /admin. But depending upon your need you can keep it unsecure, use basic HTTP auth or go with something more detailed.
Not sure if in this particular case it is wise, but it is possible indeed to create a .properties file anywhere on the filesystem - and link it into your application by means of a Resources element.
https://tomcat.apache.org/tomcat-8.0-doc/config/resources.html
The Resources element represents all the resources available to the web application. This includes classes, JAR files, HTML, JSPs and any other files that contribute to the web application. Implementations are provided to use directories, JAR files and WARs as the source of these resources and the resources implementation may be extended to provide support for files stored in other forms such as in a database or a versioned repository.
You would need a PreResources element here, linking to a folder, the contents of which will be made available to the application at /WEB-INF/classes.
<Context antiResourceLocking="false" privileged="true" docBase="${catalina.home}/webapps/myapp">
<Resources className="org.apache.catalina.webresources.StandardRoot">
<!-- external res folder (contains settings.properties) -->
<PreResources className="org.apache.catalina.webresources.DirResourceSet"
base="/home/whatever/path/config/"
webAppMount="/WEB-INF/classes" />
</Resources>
</Context>
Your application now 'sees' the files in /home/whatever/path/config/ as if they were located at /WEB-INF/classes.
Typically, the Resources element is put inside a Context element. The Context element must be put in a file located at:
$CATALINA_BASE/conf/[enginename]/[hostname]/ROOT.xml
See https://tomcat.apache.org/tomcat-8.0-doc/config/context.html#Defining_a_context
We build 3-tier enterprise solutions that typically consists of several webapp and ejbjar modules that all talk to a db and have several external integration points.
Each module typically needs its own configurations that can change over the solution's life time.
Deploying it becomes a nightmare because now we have 18 property files that must be remembered to copied over and configured also setting up data-sources, queues, memory requirements etc.
I'm hopeful but not optimistic that there can be a better way.
Some options we've considered/used, each with it's pros and cons:
Use multiple maven projects and continuous integration (eg. hudson or jenkins) to build a configuration jar that includes all the property files for each environment (dev, qa, prod) and then bundle everything up as an EAR. But then things can't be easily changed in production when needed.
Put most of the settings in the DB and have a simple screen to modify it. Internally we can have a generic configuration service EJB that can read and modify the values. Each module can have a custom extended version that have specific getters and setter.
Version control all the property files then check it out on production and check it into a production branch after making changes.
With all of these you still need to configure data-sources and queues etc. in a container specific way :(
Сonsider binding a custom configuration object to JNDI. Then lookup this object in your apps to configure them. Benefits - you can use custom configuration object instead of rather generic Map or Properties.
Another way is to use JMX to configure applications you need. Benefits - you can bind objects you have to configure directly to MBean Server and then use such a well-known tools as jconsole or visualvm to configure components of your application.
Both ways support dynamic reconfiguration of your applications at runtime. I would prefer using JMX.
I've gone through several cycles of finding ways to do this. I still don't have a definite answer.
The last cycle ended up with a process based on properties files. The idea was that each server instance was configured with a single properties file that configured everything. That file was read by the startup scripts, to set memory parameters, by the app server, and by the application itself.
The key thing, though, was that this file was not managed directly. Rather, it was a product of the build process. We had a range of files for different purposes, kept in version control, and a build step which merged the appropriate ones. This lets you factor out commonalities that are shared along various axes.
For example, we had development, continuous integration, QA, UAT, staging, and production environments, each with its own database. Servers in different environments needed different database settings, but each server in a given environment used the same settings. So, there was something like a development-db.properties, qa-db.properties, and so on. In each environment, we had several kinds of servers - web servers, content management servers, batch process servers, etc. Each had JVM settings, for heap size and so on, that were different to other kinds of servers, but consistent between servers across environments. So, we had something like web-jvm.properties, cms-jvm.properties, batch-jvm.properties, and so on. We also had a way to have overrides for specific systems - production-cms-jvm.properties sort of thing. We also had a common.properties that set common properties, and sensible defaults which could be overridden where needed.
Our build process was actually a bit more complicated than just picking the right options from each set; we had a master file for each server in each environment which specified which other files to include. We allowed files to specify other files to include, so we could build a graph of imports to maximise reuse.
It ended up being quite complicated. Too complicated, i think. But it did work, and it did make it very, very easy to make changes affecting many servers in a controlled way. We even merged a set of input files from development, and another from operations, which contained sensitive information. It was a very flexible approach.
I know this has already been answered and my answer is not necessarily generic, but here's my take on things:
Note, here I'm only considering system/resource properties, not application settings. In my view, application settings (such as a payment threshold or other settings should be stored in a database, so that the system can be reconfigured without having to restart a service or cause downtime by re-deploying or re-reading a properties file).
For settings that impact on how different parts of a system connect with each other (such as web service endpoints, etc), I would make use of the JNDI tree.
Database connectivity and JMS connectivity would then be set-up using the Websphere console and can be managed by the Websphere administrators. These can also be created as JACL scripts which can be put into version control if necessary.
In addition to the JNDI resources, for additional properties, such as usernames for web service calls to a backend, etc, I would use Websphere "Name Space Bindings". These bindings can be edited using the Websphere console and accessed via JNDI using the "cell/persistent/mypassword" name.
So I could create the "mypassword" binding (a string), and the management for it falls to the Websphere admin (away from developer eyes or other people who should not have access to production systems), while the same EAR file can be used on dev, test, preproduction and production (which is preferable to have different EAR files for different systems, as the likelihood of other differences creeping in is reduced).
The Java code would then use a simple JNDI lookup (and possibly cache the value in memory).
Advantages over properties files:
Not having a "vulnerable" file that would need to be secured because system properties contain passwords.
Not having to add Java security policies to allow access to that file location
Advantages over database properties:
Not tied to having one database tied to an application server.
Hope that helps
Use multiple maven projects and continuous integration (eg. hudson or
jenkins) to build a configuration jar that includes all the property
files for each environment (dev, qa, prod) and then bundle everything
up as an EAR. But then things can't be easily changed in production
when needed.
I think the config should be in the database of the application instance. Your local machine config may be diffrent to dev and to QA, PROD , DR etc.
What you need is a way of getting the config out the database in a simple way.
I create a separate project with a provided dependency of Apache commons-configuration
It has many ways of storing data, but I like databases and the configurations lives in the database environment.
import javax.sql.DataSource;
import org.apache.commons.configuration.DatabaseConfiguration;
public class MYConfig extends DatabaseConfiguration {
public MYConfig(DataSource datasource) {
super(datasource, "TABLE_CONFIG", "PROP_KEY", "PROP_VALUE");
}
}
Put most of the settings in the DB and have a simple screen to modify
it. Internally we can have a generic configuration service EJB that
can read and modify the values. Each module can have a custom extended
version that have specific getters and setter.
Commons configurations as a simple API, you may then write the GUI as you wish.
You can do the interface in anyway you wish. Or as a quick win have no interface.
Version control all the property files then check it out on production
and check it into a production branch after making changes.
Version control is great. Add another DatabaseConfiguration using composition. The class you extends is the active config and the composed one being the audit. There is another constructor can can have a version. Just overload the right methods to get the desired effect.
import javax.sql.DataSource;
import org.apache.commons.configuration.DatabaseConfiguration;
public class MYConfig extends DatabaseConfiguration {
final DatabaseConfiguration audit;
public MYConfig(DataSource datasource) {
super(datasource, "TABLE_CONFIG", "PROP_KEY", "PROP_VALUE");
audit = new DatabaseConfiguration("TABLE_CONFIG_AUDIT", "PROP_KEY", "PROP_VALUE");
}
#Override
public void addProperty(String key, Object value) {
Object wasValue = super.getProperty(key);
super.addProperty(key, value);
audit.put(key,wasValue);//add version code
}
}
http://commons.apache.org/proper/commons-configuration/
User a simple database table (Section, Key, Value). Add "Version" if you need it, and wrap the entire thing in a simple ConfigurationService class with methods like getInt(String section, String key)
Not a lot of work, and it makes the application code very neat, and tweaking with the configuration very easy.
Interesting alternative config file format: write a scala trait. Your config file can then just be a scala file that you compile and evaluate when the server starts.
http://robey.lag.net//2012/03/26/why-config.html
There is a team develops enterprise application with web interface: java, tomcat, struts, mysql, REST and LDAP calls to external services and so on.
All configuration is stored in context.xml --tomcat specific file that contains variables available via servlet context and object available via JNDI resources.
Developers have no access to production and QA platforms (as it should be) so context.xml is managed by support/sysadmin team.
Each release has config-notes.txt with instructions like:
please add "userLimit" variable to context.xml with value "123", rename "DB" resource to "fooDB" and add new database connection to our new server (you should know url and credentials) named "barDb"
That is not good.
Here is my idea how to solve it.
Each release has special config file with required variable names, descriptions and default values (if any): even web.xml could be used.
Here is pseudo example:
foo=bar
userLimit=123
barDb=SET_MANUAL(connection to our new server)
And there is a special tool that support team runs against deployment artifact.
Look at it (text after ">" is typed by support guy):
Config for version 123 of artifact "mySever".
Enter your config file location> /opt/tomcat/context/myServer.xml
+"foo" value "bar" -- already exists and would not be changed
+"userLimit" value "123" -- adding new
+"barDb"(connection to our new server) please type> jdbc:mysql:host/db
Saving your file as /opt/tomcat/context/myServer.xml
Your environment is not configured to run myServer-123.
That will give us ability to deploy application on any environment and update configuration if needed.
Do you like my idea? What do you use for environment configuration management? Does there is ready-to-use tools for that?
There are plenty of different strategies. All of them are good and depends on what suit you best.
Build a single artifact and deploy configs to a separate location. The artifact could have placeholder variables and, on deployment, the config could be read in. Have a look at Springs property placeholder. It works fantastically for webapps that use Spring and doesn't involve getting ops involved.
Have an externalised property config that lives outside of the webapp. Keep the location constant and always read from the property config. Update the config at any stage and a restart will be up the new values.
If you are modifying the environment (i.e. application server being used or user/group permissions) look at using the above methods with puppet or chef. Also have a look at managing your config files with these tools.
As for the whole should devs be given access to prod, it really depends on a per company basis. For smaller companies where the dev is called every time there is a problem, regardless of whether that problem is server or application related, then obviously devs require access to the box.
DevOps is not about giving devs access to the box, its about giving devs the ability to use infrastructure as a service, the ability to spawn new instances with application X with config Y and to push their applications into environments without ops. In a large company like ours, what it allows is the ability for devs to manage the application they put on a server. Operations shouldn't care what version is on their, thats our job, their job is all about keeping the server up and running.
I strongly disagree with your remark that devs shouldn't have access to prod or staging environments. It's this kind of attitude that leads to teams working against each other instead of with eath other.
But to answer your question: you are thinking about what is typically called continuous integration ( http://en.wikipedia.org/wiki/Continuous_integration ) and moving towards devops. Ideally you should aim for the magic "1 click automated deployment". The guys from Flickr wrote a lot of blogs (and books) about how they achieved that.
Anyhow .. there's a lot of tools around that sector. You may want to have a look a things like Hudson/Jenkins or Puppet/Chef.