Problem
Your organization has many separate applications, some of which interact with each other (to form "systems"). You need to deploy these applications to separate environments to facilitate staged testing (for example, DEV, QA, UAT, PROD). A given application needs to be configured slightly differently in each environment (each environment has a separate database, for example). You want this re-configuration to be handled by some sort of automated mechanism so that your release managers don't have to manually configure each application every time it is deployed to a different environment.
Desired Features
I would like to design an organization-wide configuration solution with the following properties (ideally):
Supports "one click" deployments (only the environment needs to be specified, and no manual re-configuration during/after deployment should be necessary).
There should be a single "system of record" where a shared environment-dependent property is specified (such as a database connection string that is shared by many applications).
Supports re-configuration of deployed applications (in the event that an environment-specific property needs to change), ideally without requiring a re-deployment of the application.
Allows an application to be run on the same machine, but in different environments (run a PROD instance and a DEV instance simultaneously).
Possible Solutions
I see two basic directions in which a solution could go:
Make all applications "environment aware". You would pass the environment name (DEV, QA, etc) at the command line to the app, and then the app is "smart" enough to figure out the environment-specific configuration values at run-time. The app could fetch the values from flat files deployed along with the app, or from a central configuration service.
Applications are not "smart" as they are in #1, and simply fetch configuration by property name from config files deployed with the app. The values of these properties are injected into the config files at deploy-time by the install program/script. That install script takes the environment name and fetches all relevant configuration values from a central configuration service.
Question
How would/have you achieved a configuration solution that solves these problems and supports these desired features? Am I on target with the two possible solutions? Do you have a preference between those solutions? Also, please feel free to tell me that I'm thinking about the problem all wrong. Any feedback would be greatly appreciated.
We've all run into these kinds of things, particularly in large organizations. I think it's most important to manage your own expectations first, and also ask whether it's really necessary to tell every system and subsystem on a given box to "change to DEV mode" or "change to PROD mode". My personal recommendation is as follows:
Make individual boxes responsible for a different stage - i.e. "this is a DEV box", and "this is a PROD box".
Collect as much of the configuration that differs from box to box in one location, even if it requires soft links or scripts that collect the information to then print out.
A. This way, you can easily "dump this box's configuration" in two places and see what differs, for example after a new deployment.
B. You can also make configuration changes separate from software changes, at least to some degree, which is a good way to root out bugs that happen at release time.
Then have everything base its configuration on something/somewhere that is not baked-in or hard-coded - just make sure to collect and document it in that one location. It almost doesn't matter what the mechanism is, which is a good thing, because some systems just don't want to be forced to use some mechanisms or others.
Sorry if this is too general an answer - the question was very general. I've worked in several large software-based organizations before, and this seemed to be the best approach. Using a standalone server as "one unit of deployment" is the most realistic scenario (though sometimes its expensive), since applications affect each other, and no matter how careful you are, you destabilize a whole system when you move any given gear or cog.
The alternative gets very complex very quickly. You need to start rewriting the applications that you have control over in order to have them accept a "DEV" switch, and you end up adding layers of kludge to the ones you don't have control over. Usually, the ones you don't have control over at least base their properties on something defined on a system-wide level, unless they are "calling the mothership for instructions".
It's easier to redirect people to a remote location and have them "use DEV" vs "use PROD" than it is to "make this machine run like DEV" vs "make this machine run like PROD". And if you're mixing things up, like having a DEV task run together on the same box as a PROD task, then that's not a realistic scenario anyways: I guarantee that eventually you will be granting illegal DEV-only access to somebody on PROD, and you'll have a DEV task wipe out a PROD database.
Hope this helps. Let me know if you'd like to discuss more specifics involved.
I personally prefer solution 2 (the app should know itself, by its configuration, what environment it is running in). With solution 1 (pass the environment name as a startup parameter) the danger of using the wrong environment specifier is much too high. Accessing the TEST database from PROD code and vice versa may cause mayhem, if the two installed code bases are not of the same version, as is often the case.
My current project uses solution 1, but I don't like that. A previous project I worked on used a variation of solution 2: The build process generated one setup file for every environment, making sure that they contained the same code base but appropriate configuration paramters. That worked like a charm, but I know it contradicts the paradigm that the "exact same build files must be deployed everywhere".
I think I have asked a related, self-answered, question, before I read this one : How to organize code so that we can move and update it without having to edit the location of the configuration file? . So, on that basis, I provide an answer here. I don't like the idea of "smart" application (solution 1 here) for such a simple task as finding environment settings. It seems a complicated framework for something that should be simple. The idea of an install script (solution 2 here) is powerful, but it is useful to allow the user to change the content of the config file, but would it allow to change the location of this config file? What is this "central configuration service", where is it located? My answer is that I would go with option 2, if the goal is to set the content of the configuration file, but I feel that the issue of the location of this configuration file remains unanswered here.
If you're using JSON to store/transmit configuration (or can use JSON in your pre-deploy process to output to some other format) you can annotate key/property names for environment/context-specific values with arbitrary or environment-specific suffixes, and then dynamically prefer/discriminate them at build/deploy/run/render -time, while leaving un-annotated properties alone.
We have used this to avoid duplicating entire configuration files (with the associated problems well known) AND to reduce repetition. The technique is also perfect for internationalization (i18n) -- even within the same file, if desired.
Example, snippet of pre-processed JSON config:
var config = {
'ver': '1.0',
'help': {
'BLURB': 'This pre-production environment is not supported. Contact Development Team with questions.',
'PHONE': '808-867-5309',
'EMAIL': 'coder.jen#lostnumber.com'
},
'help#www.productionwebsite.com': {
'BLURB': 'Please contact Customer Service Center',
'BLURB#fr': 'S\'il vous plaît communiquer avec notre Centre de service à la clientèle',
'BLURB#de': 'Bitte kontaktieren Sie unseren Kundendienst!!1!',
'PHONE': '1-800-CUS-TOMR',
'EMAIL': 'customer.service#productionwebsite.com'
},
}
... and post-processed (in this case, at render time) given dynamic, browser-environment-known location.hostname='www.productionwebsite.com' and navigator.language of 'de'):
prefer(config,['www.productionwebsite.com','de']); // prefer(obj,string|Array<string>)
JSON.stringify(config); // {
'ver': '1.0',
'help': {
'BLURB': 'Bitte kontaktieren Sie unseren Kundendienst!!1!',
'PHONE': '1-800-CUS-TOMR',
'EMAIL': 'customer.service#productionwebsite.com'
}
}
If a non-annotated ('base') property has no competing annotated property, it is left alone (presumably global across environments) otherwise its value is replaced by an annotated value, if the suffix matches one of the inputs to the preference/discrimination function. Annotated properties that do not match are dropped entirely.
You can mix and match this behaviour to annotate configuration to achieve distinctions of global, default, specific that are (assuming you're sensible) readable with zero/minimal duplication.
The single, recursive prefer() function (as we're calling it, lacking the need or desire to make an entire project/framework out of it) we've developed so far (see jsFiddle, with inline docs) goes a bit further than this simple example, and (explained in greater detail here) handles deeply-nested configuration objects, as well as preferential ordering and (if you need to stay flat) combination of suffixes.
The function relies on JS ability to reference object properties as strings, dynamically, and tolerate # and & delimiters in property names which are not valid in dot-notation syntax but consequently (help) prevent developers from breaking this technique by accidentally referring to pre-processed/annotated attributes in code (unless they, non-conventionally don't prefer to use dot-notation.)
We have yet to have this break anything for us, nor have we been schooled on any fundamental flaws of this technique, beyond irresponsible/unintended usage or investment/fondness for existing frameworks/techniques that pre-exist. We have also not profiled it for performance (we only tend to run this once per build/session, etc.) so in your own usage, YMMV.
Most configurations transmitted client-side of course would not want to contain sensitive pre-production values, so one could (should!) use the same function to generate a production-only version (with no annotations) in pre-deploy, while still enjoying a SINGLE configuration file upstream in your process.
Further, if you're doing this for i18n, you may not want the entire wad going over the wire, so could process it server-side (cached or live, etc.) or pre-process it in build/deploy by splitting into separate files, but STILL enjoying a single source of truth as early in your workflow as possible.
We have not explored implementing the same function in Java (or C#, PERL, etc.) assuming it's even possible (with some exotic reflection maybe?) but a build environment that includes NodeJS could farm that step out easily.
Well if it suits your needs and you have no problem of storing the connection strings in the source control repository, you could create files like:
appsettings.dev.json
appsettings.qa.json
appsettings.staging.json
And choose the right one in the deployment script and rename it to the actual appsettings.json, which is then read by your app.
Related
I have a VSTS account within the region of US. And I have a bunch of Unit tests, which run successfully on my local server. But when deployed to the VSTS, all the tests related to the date time are failed. I guess this is because the interpretation of the date time format is different as my local is using the UK format. Because there are quite a number of test projects, instead of changing it individually, is there any way to change the VSTS default thread's current culture as UK? I know probably the change of region might do the trick, but any other way?
Of course, a lot is possible, but it would be a far better idea to make sure your application correctly handles accidentally being deployed to a machine with a different culture.
You've basically uncovered an unexpected and unwanted behaviour of your code, or you've detected that you're not able to run in different cultures.
I'd personally try to make the code more resilient, e.g. explicitly set the right culture and depend on InvariantCulture where possible.
If you want the easy way out, you can do one of the following:
Use an initializer
Add one method to your test project and decorate it with the [AssemblyInitializer] attribute:
[TestClass()]
public sealed class CultureInitializer
{
[AssemblyInitialize()]
public static void AssemblyInit(TestContext context)
{
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-GB");
Thread.CurrentThread.CurrentUiCulture = new CultureInfo("en-GB");
}
}
Force the user profile culture settings
I recommend you don't do this, while it shouldn't, it may influence other processes running after your tests, change output formats or cause other unwanted behaviours similar to what you're now experiencing.
The data is stored in the registry in the following location:
HKEY_CURRENT_USER\Control Panel\International
You'll want to change the value before starting the tests, as these values are read from the system when starting the application unless you're registering for the events to be signalled when these values change, your tests will not see the difference.
Run a script in the build definition before the tests start
Set-Culture -CultureInfo en-GB
I've been given the task of researching whether one can use Powershell to automate the managing of References in VB6 application and then compile it's projects afterwards.
There are 3 projects. I requirement is to remove a specific reference in each project. Then, compile projects from bottom up (server > client > interface) and add reference back in along the way. (remove references, compile server.dll >add client reference to server.dll, compile client.dll > add interface reference to client.dll, compile interface.exe)
I'm thinking no, but I was still given the task of finding out for sure. Of course, where does one go to find this out? Why here of course, StackOverflow.
References are stored in the project .VBP files which are just text files. A given reference takes up exactly one line of the file.
For example, here is a reference to DAO database components:
Reference=*\G{00025E01-0000-0000-C000-000000000046}#5.0#0#C:\WINDOWS\SysWow64\dao360.dll#Microsoft DAO 3.6 Object Library
The most important info is everything to the left of the path which contains the GUID (i.e., the unique identifier of the library, more or less). The filespec and description text are unimportant as VB6 will update that to whatever it finds in the registry for the referenced DLL.
An alternate form of reference is for GUI controls, such as:
Object={BDC217C8-ED16-11CD-956C-0000C04E4C0A}#1.1#0; tabctl32.ocx
which for whatever reason never seem to have a path anyway. Most likely you will not need to modify this type of reference, because it would almost certainly break forms in the project which rely on them.
So in your Powershell script, the key task would be to either add or remove the individual reference lines mentioned in the question. Unless you are using no form of binary compatibility, the GUID will remain stable. Therefore, you could essentially hardcode the strings you need to add/remove.
Aside from all that, its worth thinking through why you need to take this approach at all. Normally to build a VB6 solution it is totally unnecessary to add/remove references along the way. Also depending on your choice of deployment techniques, you are probably using either project or binary compatibility which tends to keep the references stable.
Lastly, I'll mention that there are existing tools such as Kinook's Visual Build Pro which already know how to build groups of VB6 projects and if using a 3rd party tool like that is an option, could save you a lot of work.
I have a question related to V4L-DVB drivers. Following the
Building/Compiling the Latest V4L-DVB Source Code link, there are 3 ways to
compile. I am curious about the last approach (More "Manually
Intensive" Approach). It allows me to choose the components that I
wish to build and install using the "make menuconfig". Some of these components (i.e. "CONFIG_MEDIA_ATTACH") are used in pre-processor directives that define a function in one shape if defined, and a function in another if not defined (i.e.
dvb_attach, dvb_detach) in the resulting modules (i.e. dvb_core.ko)
that will be loaded by most of the DVB drivers. What happens if there are two
drivers (*.ko modules) on the same host machine, one that needs dvb_core.ko with
CONFIG_MEDIA_ATTACH defined and another that needs dvb_core.ko with
CONFIG_MEDIA_ATTACH undefined, is there a clean way to handle this?
What is also not clear to me is: Since the V4L compilation environment seems very customizable (by setting the .config file), if I develop a driver using V4L-DVB structures, there is a big chance that it has conflicts with other drivers since each driver has its own custom settings. Is my understanding correct?
Thanks!
Dave
Update: TL;DR there seems to be no built-in way to achieve this, so a custom task is an easy solution.
Capistrano provides facilities to share files and directories over all releases. This is convenient and provides even some safety on files that should not be easily changed (or must remain the same across releases), e.g. a database configuration file.
But when it comes to replace or just update one of these shared files, I end up doing it manually, directly on the target machine. I would like to improve on that, for instance by asking Capistrano to overwrite some or all shared files when deploying. A kind of --force flag with some granularity.
I am not aware of any such kind of facility, and failing so far in my search. Any pointer?
Thinking about it
One of the reason why this facility does not exist (except that I did not find it!) is that it may be harder than it looks. For example, let's assume we have a shared database configuration file, and we exclude it from version control for security reason (common practice). Current release relies on version 1 of the DB configuration. The next release requires version 2 of the DB configuration. If the deployment goes well, everything's good. It gets harder when rolling back after some error with the new release (e.g. a regression), as version 1 must then be available.
Such automation would be cool and convenient, but dangerous as well. Yet I have practical use cases at hand.
I created a template method to do this. For example, I could have a task like this:
task :create_database_yml do
on roles(:app, :db) do
within(shared_path) do
template "local/path/to/database.yml.erb",
"config/database.yml",
:mode => "600"
end
end
end
And then I have a database.yml.erb template that uses things like fetch(:database_password) to fill in appropriate values. You can use the ask method in Capistrano to prompt for these values so they are never committed.
The implementation of template can be very simple: you just need to read the file, pass it through ERB, and then use Capistrano's upload! to place the results on the server.
My version is a little more complicated than yours probably needs to be, but in case you are curious:
https://github.com/mattbrictson/capistrano-mb/blob/7600440ecd3331945d03e059368b75849857f1fb/lib/capistrano/mb/dsl.rb#L104
One approach is to use a system configuration tool like Chef or Puppet to deploy the configuration files distinctly from Capistrano.
Another approach is to create a custom task to do this: https://coderwall.com/p/wgs6gw/copy-local-files-to-remote-server-using-capistrano-3
I personally don't change on-server configs often enough or on enough servers yet to have tried to automate it. Crafting an scp command which copies the desired config file to all of the required servers has sufficed in the past.
What is a good strategy for dealing with changing product and feature names in source code. Here's the situation I find myself in over and over again (most of you can relate?)...
Product name starts off as "DaBomb"
Major features are "Exploder", "Lantern" and "Flag".
Time passes, and the Feature names are changed to "Boom", "Lighthouse" and "MarkMan"
Time passes, and the product name changes to "DaChronic"
...
...
Blah, blah, blah...over and over and over
And now we have a large code base with 50 different names sprinkled around the directory tree and source files, most of which are obsolete. Only the veterans remember what each name means, the full etimologic history, etc.
What is the solution to this mess?
Clarification: I don't mean the names that customers see, I mean the names of directories, source files, classes, variables, etc. that the developers see where the changing product and feature names get woven into.
Given your clarification that you "don't mean the names that customers see, [you] mean the names of directories, source files, classes, variables, etc. that the developers see", yeah, this can be an annoying problem.
The way teams I've been on have coped with best when we've had a policy of always using only one name for each thing in the code base. If the name changes later on we either stay with the old name in the code, or we migrate all instances of the old name to the new name. The important thing is to never start using the new name in the code unless all instance of the old name have been migrated. That way you only ever have to keep 2 names for something in your head: the "old name", used in the code, and the name everyone else uses.
We've also often chosen a very generic/descriptive name for things when starting out if we know the "brand name" is likely to change.
I consider renaming to better naming conventions just another form of refactoring. Create a branch, perform the renames, run unit/integration tests, commit, merge, repeat. It's all about process control to keep consistency in the project.
The solution to the mess is to not create it in the first place. Once a code path is named, there's rarely a good reason to change it and never a good reason to use a new name alongside the old one. When "Exploder" becomes "Boom", you have two choices: Either keep using Exploder exclusively, and never mention Boom anywhere, or change all instances of Exploder to Boom and then continue on using Boom exclusively and never mention Exploder again.
If you're using both Exploder and Boom in the same code base, you're doing it wrong.
Also, I know you clarified that you're not talking about the user-visible names, but, if you start out working with your own internal names which are relevant to what the code does and completely independent of what marketing wants to call the product/feature, then this is much less likely to become an issue. If you're already referring to Exploder internally as TNT, then what difference does it make if Exploder gets changed to Boom?
How do you deal with Localization? Same thing; same method.
We use an internal and and external name. It could be as simple as a static variable definition like
public static final String EXPLODER = "Boom";
And in code you'll always use the reference to EXPLODER. Same for path names and the like - hard coding those paths at different places is a no-go anyway. If some guys starts digging through internal stuff (like JS sources or ini files or whatever), who cares if they discover Exploder?
Just use internal names, and ignore changes to marketing/official names: https://softwareengineering.stackexchange.com/a/208578/55472.