I've been reading for a long time on various places about modules and how they work with IIS 7+. On a test server we installed Advanced Logging and got it configured the way we would like. A question came up though that I can't answer and that is will it take down any of our websites if I install the module? There are a few posts out there that talk about how to install the Advanced logging and some of them mention restarting IIS, or restarting the application pools (which I opted to not do just to see if I really had too, turns out I didn't have to) but as I've learned in the past is to not trust that if I didn't explictly do something it doesn't mean it wasn't done in the background.
The concern boils down to that we have 1 particular website that we want to installed Advanced Logging to. The website is heavily used 24/7 and taking it down unintentionally could get me in loads of trouble. hence my question. If I do install this will it take down our website temporarily to install the module or will it be smart about it and the feature will be available as the app pools cycle on their own?
It depends on the module and what the module changes, if the module modifies the web.config then it will will cause the application pools to restart.
Some modules will modify the applicationhost.config. I believe this module does that and it really depends on what gets modified in that file, some modification will cause restarting and others will not.
You can definitely test installing it on a test machine and see if the pools recycle. That's the approach I would take to get a definitive answer.
Related
I am playing with node.js and angular for first time. I use shared server hosting space. I am trying to get some node.js tests running.
CPanel seem to provide interface to deploy node applications. Example:
application url: myurl.com
application root: node-hello-world
application startup file: app.js
This seems to create directory and some artifacts in
/home/myurl/nodevenv/node-hello-world/6/bin
I have (limited?) shell access through Cpanel emulation, however I get error on source command.
source activate
got error: error: jailshell: fork: Cannot allocate memory
Does this mean node.js is installed and ready to run? Do I have to upload project as well? Where to? Trying to find more info on process of deploying to this type of server if possible.
sorry for nooby question.
Googling your error message, I came across this thread -- which admittedly is very old, but it's from cPanel and has the following comment from an administrator at the time:
Jailshell is a constrained environment by design. It is not meant to be a replacement for a full-featured, unrestricted, shell environment, such as is provided by Bash. If your user's need such full-featured environments then perhaps they need full shell access, or another method whereby they can accomplish their goal.
That answer was given in 2006 (yes, 13 years ago) but I have to imagine the spirit of that response is still true.
To be perfectly honest, I'd be afraid to use any shared hosting provider that would give you more than very limited shell to use -- it opens the door to many security vulnerabilities, and if multiple customers are in the same runtime (i.e. shared hosting) it could be catastrophic. Maybe your host does allow this, or maybe what you're describing isn't actually the same thing I'm referring to... you didn't offer a lot of details on this point.
Back to your question: Does this mean node.js is installed and ready to run? Do I have to upload project as well? Where to?
If I had to guess, Node probably isn't installed (it isn't in most shared hosting providers) -- but I can't say for sure based on the information you provided. My recommendation would be to call their customer support. Or pay for a dedicated hosting account where you get root access. Or just use something like Heroku.
I'm a little surprised that I can't find this answered already, but I've looked fairly hard. Apologies if I've missed it somewhere obvious.
TL;DR
Question: How do I configure CRA (with SW) and the Azure App Service into which it is deployed, so that they play nicely together?
There is a relatively well-discussed caching gotcha in the (current) default CreateReactApp config, relating to serviceWorkers.
It is lightly-discussed here, in the CRA docs: https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#user-content-opting-out-of-caching (especially, points 5 & 6 from "Offline-First Considerations").
And an extended argument about its original inclusion in CRA can be found here: https://github.com/facebook/create-react-app/issues/2398
I'm not 100% certain of my understanding, so I'm going to start by summarising what I currently believe to be true:
CRA has setup standard cache-busting processes in its main files.
CRA has included a "Service Worker" pattern to do heavy-duty, ultra-sticky caching.
The Service Worker can mostly load the page without even having an internet connection.
In principle the SW will load the page, and then go and ask the server about the latest code.
If it detects a newer version, it will download that, and cache the new version.
It will NOT immediately display the new version, but would use the new version the next time the page is loaded, from its newly-updated cache.
All this is the standard, desired, intended behaviour of Service Workers.
But further to this:
The serviceWorker is NOT cache busted.
Depending on your host server configuration, the serviceWorker itself may get cached.
If that happens, then it will permanently display the stale version of the site, until the serviceWorker is cleared from the cache, and then it will start trying to update the available content.
Default, out-of-the-box Azure configuration does cache the SW, and so far (after 24 hours) doesn't seem to release that cache at all :(
Question 0: Have I got everything above correct, or am I missing something?
I like the sound of the serviceWorker in general - it seems like it's doing a useful job, but it seems very unlikely that the CRA has provided something which when installed Out-of-box into Azure is fundamentally broken - the site I've deployed at the moment is (or gives the impression of being) impossible to push updates to!
I believe I know how to turn off the ServiceWorker, apparently including active steps required to purge it from people's browsers who have already seen it once and thus have an active SW already. (Though I don't understand clearly how that code will work!?) But I'd rather not do that if I can avoid it - I'd rather understand how to work WITH this feature, than how to DISABLE this feature.
So ...
Question: How do I configure CRA (with SW) and the Azure App Service into which it is deployed, so that they play nicely together?
In the past couple of years NodeJS became a major player in the server landscape - and I really find it hard to believe that there is no decent way to have nodejs run as a service on a linux box. On Windows we have iisnode - but for non Windows environments the forever package is suggested as the way to go - instead of a real solution.
Is there maybe a servicized version of nodejs out there that I could not locate?
There isn't a "servicized" version of Node.js available in the sense you are thinking. Keeping your Node application running (for example in the event of a fatal error) is up to you entirely.
As suggested in the first comment, this is fairly subjective, but really there are two big packages (and one or two alternative methods) for making a service out of your Node application. As you've mentioned, forever is a popular choice. If you've never taken a look at pm2, I suggest doing so, as it offers some services that forever does not. Alternatively, you could search for information on supervisord, which I've had success with in the past. Finally, daemonizing Node with upstart is something to look at if the others don't fit well for you.
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There are a bunch of managed cloud based hosting services for nodejs out there which seem relatively new and some still in Beta.
Yet another path to host a nodejs app is setting up a stack on a VPS like Linode.
I'm wondering what's the basic difference here between these two kinds of deployment.
Which factors should one consider in choosing one over another?
Which one is more suitable for production considering how young these services are.
To be clear I'm not asking on choosing a provider but to decide whether to host on a managed nodejs specific hosting or on an old fashioned self setup VPS.
Using one of the services is for the most part hands off - you write your code and let them worry about managing the box, keep your process up, creating the publishing channel, patching the OS, etc...
In contrast having your own VM gives you more control but with more up front and ongoing time investment.
Another consideration is some hosters and cloud providers offer proprietary or distinct variations on technologies. They have reasons for them and they offer value but it does mean that if you want to switch cloud providers, it might mean you have to rewrite code, deployment scripts etc... On the other hand using VMs with standard OS as the baseline is pretty generic. If you automate/script/document the configuration of your VMs and your code stays generic, then your options stay open. If you do take a dependency on a proprietary cloud technology then it would be good to abstract it away behind an interface so it's a decoupled component and not sprinkled throughout your code.
I've done both. I did the VM path recently mostly because I wanted the learning experience. I had to:
get the VM from the cloud provider
I had to update and patch the OS
I had to install and configure git as a publishing channel
I had to write some scripts and use things like forever to keep it running
I had to configure the reverse http-proxy to get it to run multiple sites.
I had to configure DNS with the cloud provider, open ports for git etc...
The list goes on. In the end, it cost me more up front time not coding but I learned about a lot more things. If those are important to you, then give it a shot. If you want to focus on writing your code, then a node hosting provider may be for you.
At the end of it, I had also had more options - I wanted to add a second site. I added an entry to my reverse proxy, append my script to start up another app with forever, voila, another site. More control. After that, I wanted to try out MongoDB - simple - installed it.
Cost wise they're about the same but if you start hosting multiple sites with many other packages like databases etc..., then the VM can start getting cheaper.
Nodejitsu open sourced their tools which also makes it easier if you do your own.
If you do it yourself, here's some links that may help you:
Keeping the server up:
https://github.com/nodejitsu/forever/
http://blog.nodejitsu.com/keep-a-nodejs-server-up-with-forever
https://github.com/bryanmacfarlane/svchost
Upstart and Monit
generic auto start and restart through monitoring
http://howtonode.org/deploying-node-upstart-monit
Cluster Node
Runs one process per core
http://nodejs.org/docs/latest/api/cluster.html
Reverse Proxy
https://github.com/nodejitsu/node-http-proxy
https://github.com/nodejitsu/node-http-proxy/issues/232
http://blog.nodejitsu.com/http-proxy-middlewares
https://github.com/nodejitsu/node-http-proxy/issues/168#issuecomment-3289492
http://blog.argteam.com/coding/hardening-node-js-for-production-part-2-using-nginx-to-avoid-node-js-load/
Script the install
https://github.com/bryanmacfarlane/svcinstall
Exit Shell Script Based on Process Exit Code
Publish Site
Using git to publish to a website
IMHO the biggest drawback of setting up your own stack is that you need to manage things like making Node.js run forever, start it as a daemon, bring it behind a reverse-proxy such as Nginx, and so on ... the great thing about Node.js - making firing up a web server a one-liner - is one of its biggest drawbacks when it comes to production-ready systems.
Plus, you've got all the issues of managing and updating and securing your server yourself.
This is so much easier with the hosters: Usually it's a git push and that's it. Scaling? Easy. Replication? Easy. ...? Easy. All within a few clicks.
The drawback with the hosters is that you can not adjust the environment. Okay, you can probably choose which version of Node.js and / or npm to run, but that's it. You have no control over what 3rd party software is installed. You've got no control over the OS. You've got no control over where the servers are located. And so on ...
Of course, some hosters allow you access to some of these things, but there is rarely a hoster that supports all.
So, basically the question regarding Node.js is the same as with each other technology: It's a pro vs con of individualism, pricing, scalabilty, reliability, knowledge, ...
I personally chose to go with a hoster: The time and effort I save easily outperform the disadvantages. Mind you: For me, personally.
This question needs to be answered individually.
Using Docker is another way to simplify the setup on single Linux VPS. With Docker both development and production setups are faster, more robust, and more secure.
The setup is faster and more robust because you will be deploying ready Node.js image at once, without running any installation scripts. And it would be more secure because internal dependencies, such as database, can be hidden from outside world completely and accessible only from Docker internal network. On top of it, Docker significantly simplifies the upgrade process for underlying OS and Node.js runtime.
There are two ways to setup Node.js Docker environment. The first one – follow the instruction published here how to dockerize your application and deploy it with Docker, alongside with databases when needed. The guide gives the instructions for the development setup, the production setup will be similar.
Another way would be deploying official Node.js docker image and mounting application code as a volume or a folder to Node.js image. That would allow to update Node.js image going forward without re-building and re-deploying the application. Such approach solves long-standing problem with security patching of Docker images.
To help out with the setup of Docker on single machine - you can use Abberit Admin Panel. It will set up Node.js environment for you with a click of a button, including databases if you need them. The tool is free, and you can turn it off after you have completed initial setup. On the other hand, if later you decide to reduce maintenance tax of the production - you can migrate into managed service without any changes in the app.
Disclaimer: I am one of the founders of Abberit.
This may be a basic question, but how do I go about effeciently deploying updates to currently running node.js code?
I'm coming from a PHP, JavaScript (client-side) background, where I can just overwrite files when they need updating and the changes are instantly available on the produciton site.
But in node.js I have to overwrite the existing files, then shut-down and the re-launch the application. Should I be worried by potential downtime in this? To me it seems like a more risky approach than the PHP (scripting) way. Unless I have a server cluster, where I can take down one server at a time for updates.
What kind of strategies are available for this?
In my case it's pretty much:
svn up; monit restart node
This Node server is acting as a comet server with long polling clients, so clients just reconnect like they normally would. The first thing the Node server does is grab the current state info from the database, so everything is running smoothly in no time.
I don't think this is really any riskier than doing an svn up to update a bunch of PHP files. If anything it's a little bit safer. When you're updating a big php project, there's a chance (if it's a high traffic site it's basically a 100% chance) that you could be getting requests over the web server while you're still updating. This means that you would be running updated and out-of-date code in the same request. At least with the Node approach, you can update everything and restart the Node server and know that all your code is up to date.
I wouldn't worry too much about downtime, you should be able to keep this so short that chances are no one will notice (kill the process and re-launch it in a bash script or something if you want to keep it to a fraction of a second).
Of more concern however is that many Node applications keep a lot of state information in memory which you're going to lose when you restart it. For example if you were running a chat application it might not remember who users were talking to or what channels/rooms they were in. Dealing with this is more of a design issue though, and very application specific.
If your node.js application 'can't skip a beat' meaning it is under continuous bombardment of incoming requests, you just simply cant afford that downtime of a quick restart (even with nodemon). I think in some cases you simply want a seamless restart of your node.js apps.
To do this I use naught: https://github.com/superjoe30/naught
Zero downtime deployment for your Node.js server using builtin cluster API
Some of the cloud hosting providers Node.js (like NodeJitsu or Windows Azure) keep both versions of your site on disk on separate directories and just redirect the traffic from one version to the new version once the new version has been fully deployed.
This is usually a built-in feature of Platform as a Service (PaaS) providers. However, if you are managing your servers you'll need to build something to allow for traffic to go from one version to the next once the new one has been fully deployed.
An advantage of this approach is that then rollbacks are easy since the previous version remains on the site intact.