new post

Author: flq

public/assets/cloud-agnostic-2.png

@@ -6,7 +6,11 @@ date: 2025-04-06 21:30:00
 topic: "azure-ahead"
 ---
 
-<TopicToc topicId="azure-ahead" active="Cloud Agnostic - introducing the AheadDockerized .NET Solution" />
+<TopicToc 
+    title="Cloud agnostic series" 
+    topicId="azure-ahead" 
+    active="Cloud Agnostic - introducing the AheadDockerized .NET Solution" 
+/>
 
 Let's quickly revisit where we're coming from—and where we’re headed:
 

public/assets/cloud-agnostic-3.png

@@ -0,0 +1,112 @@
+---
+title: "Cloud Agnostic - Storing & serving files"
+slug: cloud-agnostic-2
+tags: [software-development, dotnet, web, azure]
+date: 2025-04-13 21:30:00
+topic: "azure-ahead"
+---
+
+<TopicToc 
+    title="Cloud agnostic series" 
+    topicId="azure-ahead" 
+    active="Cloud Agnostic - Storing & serving files"
+    closed
+ />
+
+Let us start with a relatively simple, ubiquitous but necessary service: _Storage of files_. In ahead these are
+needed for attachments, images, videos and the like.
+
+```mermaid
+graph LR
+    User((User)) -->|views| Storage
+    Ahead.Web -->|uploads| Storage
+```
+
+After investigating a bit, it appears that the safest bet here is to use something that is **Amazon S3**-compatible.
+AWS, by being first here, essentially set the standard for cloud storage, and many companies will offer such 
+"S3-compatible" storage for you to use. [Here's an example from Switzerland][1].
+
+Granted, using Azure Blob Storage is straightforward from a developer perspective: Having a local "emulator"
+is as easy as saying `npm install azurite`. I could imagine that there might be a similar
+offering for S3-compatible storage, but considering that I have an Aspire-project available, 
+setting up a container is also a straightforward activity. The company [min.io][2] offers an "object store"
+that can be run at hyperscale as well as locally on a Docker container. The relevant code is [hosted at github][3]
+
+Defining such a container as a resource in Aspire looks like this:
+
+<GHEmbed showHint repo="ahead-dockerized" branch="snapshot_1" file="AppHost/Program.cs" start={10} end={19} />
+
+People who know docker containers probably recognize the different settings that are being set:
+
+* 2 environment variables that define the admin user with which we can log in at min.io's dashboard (port 9090)
+* port bindings
+* volume bindings
+* startup arguments
+
+Aspire gives you a fluent API to define settings on the different kind of resources. Interesting are also the
+two variables `minioUser`, `minioPassword` which are defined further up: 
+
+<GHEmbed repo="ahead-dockerized" branch="snapshot_1" file="AppHost/Program.cs" start={7} end={8} />
+
+During development, these values come from a "Parameters" section in `appSettings.Development.json`.
+Once I start the solution by running the `AppHost` Aspire project, I can access the min.io dashboard by 
+clicking the provided link in the Aspire dashboard:
+
+![Aspire Dashboard showing the known resources](/assets/cloud-agnostic-2.png)
+<figcaption>Aspire Dashboard showing the known resources</figcaption>
+
+In the dashboard I can log in with the provided user / password values and create an access key:
+
+![min.io console that allows to create access keys](/assets/cloud-agnostic-3.png)
+<figcaption>min.io console that allows to create access keys</figcaption>
+
+These will be required when accessing the service.
+
+<GHEmbed repo="ahead-dockerized" branch="snapshot_1" file="Ahead.Web/Infrastructure/IBlobStorage.cs" start={77} end={81} />
+
+The relevant Nuget to access the service is simply called **minio**, and provides an up-to-date library to talk to
+min.io (and by extension S3 compatible) services.
+
+The `Ahead.Dockerized` solution introduces a blob storage interface with some example API that is linked to UI in order to be able to use it:
+
+<GHEmbed repo="ahead-dockerized" branch="snapshot_1" file="Ahead.Web/Infrastructure/IBlobStorage.cs" start={9} end={14} />
+
+<Info>
+This example solution does not implement 
+multi-tenancy as this is mostly an application aspect independent of the used resources and is therefore not in the focus of this solution.
+E.g. `bucketName` would be derived from the tenant used in the current scope.
+</Info>
+
+⬇️ This is the implementation of the upload – it takes an `IFormFile` instance and stores it in the service.
+I found it amusing that, just coming from an Aspire frontend, I ended up using a fluent interface _again_.
+While they're kind of nice to read, getting there is not always as obvious as one cannot see from the API what is 
+mandatory vs what is not, hence it is sometimes something of a trial and error to get the right incantation.
+
+<GHEmbed repo="ahead-dockerized" branch="snapshot_1" file="Ahead.Web/Infrastructure/IBlobStorage.cs" start={31} end={44} />
+
+Another thing I wanted to check out is the signed url functionality - Links to files in ahead are usually written
+like `api/files/{fileId}` - the server then redirects to a signed url, which lets you see the file for a limited amount of time:
+
+```mermaid
+sequenceDiagram
+    participant A as User
+    participant B as Ahead.Web
+    participant C as Storage
+
+    A->>B: request file with fileId
+    B->>C: get pre-signed URL
+    C-->>B: return pre-signed URL
+    B-->>A: redirect to pre-signed URL
+```
+
+This is how to get the necessary url through the min.io API:
+
+<GHEmbed repo="ahead-dockerized" branch="snapshot_1" file="Ahead.Web/Infrastructure/IBlobStorage.cs" start={46} end={55} />
+
+In this case, the link expires after one hour.
+
+All in all, blob storage is, as expected, one of the easier things to treat in a cloud-agnostic way.
+
+[1]: https://flow.swiss/object-storage
+[2]: https://min.io
+[3]: https://github.com/minio/