I'm developing an app which live-streams video and/or audio from different entities. Those entities' IDs and configurations are stored as records in my DB. My app's current architecture is something such as the following:
a CRUD API endpoint for system-wide functionalities, such as logging in or editing an entity's configuration.
N-amount of other endpoints (where N is the number of entities and every endpoint's route is defined by the specific entity's ID, like so: "/:id/api/") for each entity's specific functionalities. Each entity is loaded by the app on initialization. Those endpoints are both a REST API handler and a WebSocket server for live-streaming media received from the backend which was configured for that entity.
On top of that, there's an NGINX instance which acts as a proxy and hosts our client files.
Obviously, this isn't very scalable at the moment (a single server instance handles an ever-growing amount of entities) and requires restarting my server's instance when adding/deleting an entity - which isn't ideal. I was thinking of splitting my app's server into micro-services: one for system-wide CRUD, and N others for each entity defined in my DB. Ultimately, I'd like those micro-services to be run as Docker containers. The problems (or questions to which I don't know the answers) I'm facing at the moment are:
How does one run Docker containers dynamically, according to a DB (or programmatically)? Is it even possible?
How does one update the running Docker container to be able to reconfigure that entity during run-time?
How would one even configure NGINX to proxy those dynamic micro-services? I'm guessing I'll have to use something like Consul?
I'm not very knowledgeable, so pardon me if I'm too naive to think I can achieve such architecture. Also, if you can think of a better architecture, I'd love to hear your suggestions.
Thanks!
Related
I have a project FE, BE and a DB.
now all the tutorials I found use the three in one file.
Now should it be the DB in one docker-compose file and the BE and FE in another?
Or should it be one file per project with DB, FE and BE?
[UPDATE]
The stack I'm using is Spring Boot, Postgres and Angular.
Logically your application has two parts. The front-end runs in the browser, and it makes HTTP requests to the back-end. The database is an implementation detail of the back-end and not something you separately need to manage.
So I'd consider two possible Compose layouts:
This is "one application", and there is one docker-compose.yml that manages all of it.
The front- and back-end are managed separately, since they are two separate components with a network API. You have a frontend/docker-compose.yml that manages the front-end, and a backend/docker-compose.yml that manages the back-end and its associated database.
Typical container style is not to have a single shared database. Since it's easy to launch an isolated database in a container, you'd generally have a separate database per application (or per microservice if you're using that style). Of the options you suggest, a separate Compose file only launching a standalone database is the one I'd least consider.
You haven't described your particular tech stack here, but another consideration is that you may not need a container for the front-end. If it's a plain React application, the "classic" development flow of compiling it to static files and publishing them via any convenient HTTP service still works with a Docker-based backend. You get some advantages from this path like Webpack's hashed build files, so you can avoid disrupting running clients when you push out a new build. If you separate the front- and back-ends initially, then you can change the way the front-end is deployed without affecting the back-end at all.
While trying to create a web application for shared drawing I got stuck on a problem regarding Kubernetes and scaling. The application uses an ASP.NET Core backend with SignalR for sharing the drawing data across its users. For scaling out the application I am using a deployment for each microservice of the system. For the SignalR part though, additional configuration is required.
After some research I have found out about the possibility to sync all instances of the SignalR backend either through the use of Azures SignalR Service or the use of a Redis backplane. The latter of which I have gotten to work on my local minikube environment. I am not really happy with this solution because of the following reasons:
My main concern is that like this I have created a hard bottleneck in
the system. Unlike in a chat application where data is sent only once
in a while, messages are sent for every few points drawn in the
shared drawing experience by any client. Simply put, a lot of traffic
can occur and all of it has to pass through the single Redis backplane.
Additionally to me it seems unneccessary to make all instances of the SignalR backend talk to each
other. In this application shared drawing does only occur in small groups of up to 10 clients lets
say. Groups of this size can easily be hosted on a single instance.
So without syncing all instances of the SignalR backend I would have to route the clients connection based on the SignalR group name to the right instance of the SignalR backend when the client is trying to join a group.
I have found out about StatefulSets which allow me to have a persistent address for each backend pod in the cluster. I then could somehow associate the SignalR group IDs with the pod addresses they are running on in lets say another look up microservice. The problem with this is that the client needs to be able to access the right pod from outside of the cluster where that cluster internal address does not really help.
Also I am wondering if there isnt a whole better approach to the problem since I am very new to the world of kubernetes. I would be very greatful for your thoughts on this issue and any hint towards a (better) solution.
I have two variations of a site based off a primary enrollment site. Currently a running demo of the primary enrollment site is set up and running on a remote server using docker. I'm trying to figure out what steps are needed to move both enrollment site variants A and B up to the remote server for testing and review purposes.
The first variation (branch A) was built from the primary app as master and the second (branch B) was built as a very small variation on the initial vairant, A (think a single file updated from branch A).
So far I understand that I'll have to set up a unique database for both A and B for docker to store app data depending on which enrollment site is running (e.g., enroll-db-A and enroll-db-B). Running both sites from this host will also require specifying a unique port on the dockerfile and docker-compose file since the plan is to keep the primary demo site available through the server's default port.
What I'm confused about is how to actually move the files needed for both variants up to the remote server. Because I obviously want to minimize the number of files needed to transfer up to the remote to handle serving all our sites, and because both variants A and B both largely depend on files from the primary enrollment app root, is it sufficient to simply move all the updated and necessary config files for A and B into new directories on the remote server where the directory for the primary enrollment site is located one level up as the parent of each variant directory?
To paraphrase my manager; there's probably some way to make this work, though it's not worthwhile.
My concern in posting this mostly had to do with the apparent number of redundant files that would be pushed up to the remote web server after creating two, simple variants on an original. For our demonstration purposes, having two highly similar repos in addition to the original base loaded on to the web server is not a significant concern.
So, for now, my need to have this question answered can be deferred indefinitely.
Preface
I am currently trying to learn how micro-services work and how to implement container replication and API gateways. I've hit a block though.
My Application
I have three main services for my application.
API Gateway
Crawler Manager
User
I will be focusing on the API Gateway and Crawler Manager services for this question.
API Gateway
This is a docker container running a Go server. The communication is all done with GraphQL.
I am using an API Gateway because I expect to have different services in my application each having their own specialized API. This is to unify everything.
All it does is proxy requests to their appropriate service and return a response back to the client.
Crawler Manager
This is another docker container running a Go server. The communication is done with GraphQL.
More or less, this behaves similar to another API gateway. Let me explain.
This service expects the client to send a request like this:
{
# In production 'url' will be encoded in base64
example(url: "https://apple.example/") {
test
}
}
The url can only link to one of these three sites:
https://apple.example/
https://peach.example/
https://mango.example/
Any other site is strictly prohibited.
Once the Crawler Manager service receives a request and the link is one of those three it decides which other service to have the request fulfilled. So in that way, it behaves much like another API gateway, but specialized.
Each URL domain gets its own dedicated service for processing it. Why? Because each site varies quite a bit in markup and each site needs to be crawled for information. Because their markup is varied, I'd like a service for each of them so in case a site is updated the whole Crawler Manager service doesn't go down.
As far as the querying goes, each site will return a response formatted identical to other sites.
Visual Outline
Problem
Now that we have a bit of an idea of how my application works I want to discuss my actual issues here.
Is having a sort of secondary API gateway standard and good practice? Is there a better way?
How can I replicate this system and have multiple Crawler Manager service family instances?
I'm really confused on how I'd actually create this setup. I looked at clusters in Docker Swarm / Kubernetes, but with the way I have it setup it seems like I'd need to make clusters of clusters. That makes me question my design overall. Maybe I need to not think about keeping them so structured?
At a very generic level, if service A calls service B that has multiple replicas B1, B2, B3, ... then it needs to know how to call them. The two basic options are to have some sort of service registry that can return all of the replicas, and then pick one, or to put a load balancer in front of the second service and just directly reach that. Usually setting up the load balancer is a little bit easier: the service call can be a plain HTTP (GraphQL) call, and in a development environment you can just omit the load balancer and directly have one service call the other.
/-> service-1-a
Crawler Manager --> Service 1 LB --> service-1-b
\-> service-1-c
If you're willing to commit to Kubernetes, it essentially has built-in support for this pattern. A Deployment is some number of replicas of identical pods (containers), so it would manage the service-1-a, -b, -c in my diagram. A Service provides the load balancer (its default ClusterIP type provides a load balancer accessible only within the cluster) and also a DNS name. You'd configure your crawler-manager pods with perhaps an environment variable SERVICE_1_URL=http://service-1.default.svc.cluster.local/graphql to connect everything together.
(In your original diagram, each "box" that has multiple replicas of some service would be a Deployment, and the point at the top of the box where inbound connections are received would be a Service.)
In plain Docker you'd have to do a bit more work to replicate this, including manually launching the replicas and load balancers.
Architecturally what you've shown seems fine. The big "if" to me is that you've designed it so that each site you're crawling potentially gets multiple independent crawling containers and a different code base. If that's really justified in your scenario, then splitting up the services this way makes sense, and having a "second routing service" isn't really a problem.
I have two web roles scaled up to 4 instances and at least two instances are running at a time. The certificate requested by a user via first website is pushed to blob storage and creates a queue message for the other website to read it.
I have a while loop inside the Run method implementing RoleEntryPoint to check the message, upload the certificate to store if available, apply https binding, and delete the message.
The bindings are applied to current instance and not into both. Is there a way to I can access all instances and apply bindings to both at once? If not, what are some better approaches?