I want to use Heroku for hosting my Ruby on Rails project. It will involve lots of file uploads, mostly images. Can I host and serve that static files on Heroku or is it wiser to use services like Amazon S3. What is Your opinion on that approach ? What are my options for hosting that static files on Heroku ?
To answer your question, Heroku's "ephemeral filesystem" will not serve as a storage for static uploads. Heroku is an app server, period. You have to plug into data storage elsewhere.
From Heroku's spec:
Ephemeral filesystem
Each dyno gets its own ephemeral filesystem, with a fresh copy of the most recently deployed code. During the dyno’s lifetime its running processes can use the filesystem as a temporary scratchpad, but no files that are written are visible to processes in any other dyno and any files written will be discarded the moment the dyno is stopped or restarted. For example, this occurs any time a dyno is replaced due to application deployment and approximately once a day as part of normal dyno management.
Heroku is a great option for RoR in my opinion. I have used it personally and ran to the problem that has been mentioned here already (you can't store anything in Heroku's filesystem). I therefore used S3 following this tutorial: https://devcenter.heroku.com/articles/s3
Hope it helps!
PD: Make sure not to store the S3 credentials on any file, but rather create variables as described here: https://devcenter.heroku.com/articles/config-vars
I used to have them on a file and long story short someone gained access to my Amazon account and my account was billed several thousands of dollars (just from a couple of days). The Amazon staff was kind enough to waive those. Just something to have in mind.
As pointed out, you shouldn't do this with Heroku for the specific reason of ephemeral storage, but to answer your question more broadly storing user-uploaded content on a local filesystem on any host has a few inherent issues:
You can quickly run out of local storage space on the disk
You can lose all your user-uploaded content if the hardware crashes / the directory gets deleted / etc.
Heroku, EC2, Digital Ocean, etc. all provide servers that don't come with any guarantee of persistence (ephemeral storage especially). This means that your instance may shut down at any point, be swapped out, etc.
You can't scale your application horizontally. The files on one server won't be accessible from another (or dyno, or whatever your provider of choice calls them).
S3, however, is such a widely-used solution because:
It's incredibly cheap (we store 20 TB of data for something like $500 a month)
Your uploaded files aren't at risk of disappearing due to hardware failure
Your uploaded files are decoupled from the application, meaning any server / dyno / whatever could access them.
You can always publish your S3 buckets into cloud front if you need a CDN without any extra effort.
And certainly many more reasons. The most important thing to remember, is that by storing uploaded content locally on a server, you put yourself in a position where you can't scale horizontally, regardless of how you're hosting your app.
It it wiser to host files on S3, and actually it is even more wiser to use direct uploads to S3.
You can read the arguments, for example, here.
Main point: Heroku is really, really expensive thing.
So you need to save every bit of resources you have. And the only option to store static files on Heroku is having separate dyno running app server for you. And static files don't need app server. So it's just a waste of CPU time (and you should read that as "a waste of a lot of my money").
Also, uploading huge amount of huge files will quickly get you out of memory quota (read that as "will waste even more of my money because I will need to run more dynos"). So it's best to upload files directly to S3.
Heroku is great for hosting your app. Use the tool that best suites the task.
UPD. Forgot to tell you – not only you will need separate dyno for static assets, your static assets will die every time this dyno is restarted.
I had the same problem. I do solve it by adding all my images in my rails app. I then reference the images using their links that might be something like
myapp.herokuapp.com/assets/image1.jpg
I might add the link from the CMS. It might not be the best option, but it works.
Related
I am working on a project using Rails as my backend API server. Uploading clients' files will be one of the most important part of this application (it is something like a CRM/ERP system). However, my client prefer storing all the data and files into their own server due to security and privacy issues of their clients.
However, while I am reading the documents of ActiveStorage, it sounds like :disk option is just used for test and development environment. I understand using cloud storage like s3 would benefit on scalability and backup stuffs that are much secure and flexible for web development, but after all, you know, client's requirement.
1) Therefore, would like to know is it not preferred to use :disk on any production environment? What will be the cons that I may miss out?
Also, will it be hard for me to do backup for the files, as I saw in the /storage path, the files are all saved not into the same names of the original files.
I am having a guess that, could I just backup the whole sites by just doing pg_dump and a clone of the entire site directory including the /storage file (they will be gitignore, so I need to backup them by myself and do some git clone git pull stuff while doing recovery or server transition). Will this workflow work flawlessly?
2) What should be the actual backup and recover flow if I use :disk option in ActiveStorage?
Thanks for your help, and am appreciate any of your helps!
Disk and local are indeed not recommended for production.
If you lose the table contents or some of the files in storage/ you may not be able to recover your data.
The growing storage/ directory will make it difficult to move your application somewhere else as you'd have to copy all of the content along with the code.
It will also make it difficult scaling horizontally as the storage/ directory must be present on all instances of your applications and always in sync. You may counter this issue by setting up a NFS share somewhere and mounting under storage/ but that can come with some reliability issues - a timeout or permissions error when writing a file for instance will generate the ActiveStorage table entry but without the associated file => lots of annoying errors.
I believe it may also be rather difficult making incremental backups, you'd have to dump the table and zip it along with all of storage/ files, if something changes while you're backing up or restoring your data you'll experience all kinds of errors.
These are not really impossible to work around, just rather unfeasible.
You may want to check out Minio or a similar application. It gives you ActiveStorage support with none of the S3 costs and data privacy concerns. Just drop it on a docker instance somewhere on your network, set up persistence and backups/RAID and you're kind of done.
I saw this question:After git push heroku - uploaded files on Heroku are lost
each time the application shuts down and restarts after being inactive
for x minutes), your application is recreated and all stored data is
lost.(C)
Right now I have user which can upload two photos.I got email confirmation of new users. So I can check that user registered and uploaded photo 4 and 14 hours ago.
I've made my last commit and pushed it to heroku around 19 hours ago. And this 4 images, that new users uploaded are lost now.But I can see images if I just now register the user. So it seems to be really true that my app was inactive for x minutes and then it restarts and deletes images.
I read some questions like this Rails] Images erased after a new commit on heroku
There it says that I should use external server like aws s3( I have no idea what it is and how much it will cost and how to connect it)
So is it really true? what are my other options? may be I should simply use digital ocean(won't be there the same problem?) or something else. Will this problem continue in paid account?
I use rails and upload files using carrierwave gem, I can't upload code here cause I am writing from another laptop.
Heroku's filesystem is readonly. You can't expect anything you upload to persist there, you need to use an external storage mechanism, something like Amazon's S3 for example.
See the links for more details.
https://devcenter.heroku.com/articles/s3
https://devcenter.heroku.com/articles/dynos#isolation-and-security
The filesystem that your Heroku instance runs on is not read-only, but it is transient - i.e. files that you store there will not persist after an instance restart.
This is a deliberate design decision by Heroku, to force you to think about where you store your data and how it impacts on scalability.
You're asking about Digital Ocean - I haven't used them but I assume from your question that they allow you to store to a persistent local filesystem.
The question that you then have to ask is: what happens if you want to run more than one instance of your app? Do they share the same persistent filesystem? Can they access each other's files? How do you handle file locking to avoid race-conditions when several app instances are using the same filesystem?
Heroku's model forces you to either put stuff in a database or store it using some external service. Generally, any of these sorts of systems will be reasonably scalable - you can have multiple Heroku instances (perhaps running on different machines, different data-centers, etc), and they will all interact nicely.
I do agree that for a simple use-case where you just want to run a single instance of an app during development it can be inconvenient, but I think this is the reasoning behind it - to force you to design this sort of thing in, rather than developing your whole app on the assumption that it can store everything locally and then find out later that you need to completely redesign to make it scalable.
What you're looking at is something called the ephemeral file system in Heroku:
Each dyno gets its own ephemeral filesystem, with a fresh copy of the most recently deployed code. During the dyno’s lifetime its running processes can use the filesystem as a temporary scratchpad, but no files that are written are visible to processes in any other dyno and any files written will be discarded the moment the dyno is stopped or restarted
In short, it means that any files you upload will only last for the time the dyno is running. When the dyno shuts down, the files will be removed unless they were part of the local git repo.
The way to resolve the issue is to store the files on a third-party service - typically S3. This will store the files on a system independent of Heroku.
Both Paperclip & Carrierwave support S3 (Simple Storage Service) - through a gem called fog. S3 gives you a "free" tier, allowing you to store a certain amount of data (I've forgotten how much) for free.
I would strongly recommend setting up an S3 account and linking it to your Heroku app. This way, any files you upload will be stored off-site.
I'm deploying my web app (it's for a corporate client). So, users will not add images, but only the business will.
I've deployed to Heroku, and my images are still showing. When do I need to use S3? Ill have like 100 images in total in the site, and size will vary like > 7 a week. Can I use only heroku?
The short answer: if you allow users or admins to upload images, you should not use Heroku's file system for this as the images will suddenly vanish.
As explained in the Heroku documentation:
Each dyno gets its own ephemeral filesystem, with a fresh copy of the most recently deployed code. During the dyno’s lifetime its running processes can use the filesystem as a temporary scratchpad, but no files that are written are visible to processes in any other dyno and any files written will be discarded the moment the dyno is stopped or restarted.
This means that user uploaded images on the Heroku filesystem are not only wiped out with every push, but also with every dyno restart, which occasionally happens (even if you would ping them frequently to prevent them going to sleep).
Once you start using a second web dyno, it will not be able to read the other dyno's filesystem, so then images would only be visible from one dyno. This would cause weird issues where users can sometimes see images and sometimes they don't.
That said, you can temporarily store images on the Heroku filesystem if you implement a pass-through file upload to an external file store.
Asset Pipeline
FiveDigit's answer is very good - there is something more to consider; the role of the asset pipeline in Rails
If the images you have are used as assets (IE they are used in the layout; are not changeable by the user), then you can store them in the assets/images folder. There is no limit to the number of assets you can keep with your application, but you must be sure on what these are - they are files which aid your application's operation; not files which can be uploaded / manipulated:
The asset pipeline provides a framework to concatenate and minify or
compress JavaScript and CSS assets. It also adds the ability to write
these assets in other languages and pre-processors such as
CoffeeScript, Sass and ERB.
The asset pipeline will compress & fingerprint the stylesheet, image and js files it has, when you deploy your application to the likes of Heroku, or any other server. This means if those files don't change, you can store them in there
-
S3
The reason you'd want to use the likes of S3 is specifically if your images files are designed to change (user can upload / edit them). Regardless of Heroku's filesystem, if the images are tied to changes in the DB, you'll have to keep a central store for them - if you change servers, they need to be reachable
To do this, you should ensure you appreciate how you want the files to work - are they going to be manipulated constantly by the user or not? If so, you'll have to explore integrating S3 into your app
I have a very large site; the data, from a MySQL database hosted with Amazon RDS, is contained in two tables each with about 20M records, and the total number of pages on the site is about 40M. These pages are mostly static (they are each updated about fortnightly) and mostly do not change with user interaction. I have recently migrated the site to Rails and am testing deploying it on Heroku.
I understand that Heroku denies me access to the file system, which would otherwise be my first choice for a caching solution -- I could cache each of the mostly static 40M pages. Varnish is not available as I am on Cedar. Is memcached a suitable alternative to file system caching for a site of this size? As my database is over 30GB, would I need to purchase memcached space of commensurate size?
If memcached is not appropriate, are there any alternative caching solutions, or alternatives to Heroku altogether, where I could deploy my Rails app but take advantage of file system caching? All advice appreciated.
I would suggest that you need to look at using a simple VPS instead of Heroku. Most of these will give you ample disk space thus allowing you to use simple disk caching.
Whilst Heroku will fit most cases, this isn't one that fits well. You could purchase large amounts of Memcached space, you could also cache rendered pages in your database somehow, but I feel in this instance, you'll save more time and headaches going another route.
http://farm8.staticflickr.com/7020/6702134377_cf70482470_z.jpg
OK sorry for the terrible drawing but it seemed a better way to organize my thoughts and convey them. I have been wrestling for a while with how to create an optimal de-coupled easily scale-able system for uploading files to a web app on AWS.
Uploading directly to S3 would work except for the fact the files need to be instantly accessible to the uploader for manipulation then once manipulated they can go to s3 where they will be served to all instances.
I played with the idea of creating a SAN with something like glusterfs then uploading directly to that and serving from that. I have not ruled it out but from varying sources the reliability of this solution might be less than ideal (if anyone has better insight on this I would love to hear). In any case I wanted to formulate a more "out of the box" (in the context of AWS) solution.
So to elaborate on this diagram, I want the file to be uploaded to the local filesystem of the instance it happens to go to, which is an EBS volume. The storage location of the file would not be served to the public (i.e. /tmp/uploads/ ) It could still be accessed by the instance through a readfile() operation in PHP so that the user could see and manipulate it right after uploading. Once the user is finished manipulating the file a message to move it to s3 could be queued in SQS.
My question is then once I save the file "locally" on the instance (which could be any instance due to the load balancer), how can I record which instance it is on (in the DB) so that subsequent requests through PHP to read or move the file will find said file.
If anyone with more experience in this has some insight I would be very grateful. Thanks.
I have a suggestion for a different design that might solve your problem.
Why not always write the file to S3 first? And then copy it to the local EBS file system on whichever node you're on while you're working on it (I'm not quite sure what manipulations you need to do, but I'm hoping it doesn't matter). When you're finished modifying the file, simply write it back to S3 and delete it from the local EBS volume.
In this way, none of the nodes in your cluster need to know which of the others might have the file because the answer is it's always in S3. And by deleting the file locally, you get a fresh version of the file if another node updates it.
Another thing you might consider if it's too expensive to copy the file from S3 every time (it's too big, or you don't like the latency). You could turn on the session affinity in the load balancer (AWS calls it sticky sessions). This can be handled by your own cookie or by the ELB. Now subsequent requests from the same browser come to the same cluster node. Simply check the modified time of the file on the local EBS volume against the S3 copy and replace if it's more recent. Then you get to take advantage of the local EBS file system while the file's being worked on.
Of course there are a bunch of things I don't get about your system. Apologies for that.