C#•6mo ago

Aspire custom connection string env variable

So i just started using aspire

In my project i want to spin up a mongodb database, but my project uses a non default connection strings environment variable. The connection string should be in the variable

Database__ConnectionString

Database__ConnectionString

, but i can only get it to be the default

ConnectionString__X

ConnectionString__X

. Is there any way to "re-map" the default connectionstring varible to my custom one?

var mongodb = builder.AddMongoDB("mongodb", 27017)
    .WithMongoExpress(containerName: "express")
    .AddDatabase("database", "Development")
    ;

var api = builder.AddProject<Projects.BumpBuddy_Api>("api")
    .WithHttpHealthCheck("/health")
    .WithReference(mongodb);

var mongodb = builder.AddMongoDB("mongodb", 27017)
    .WithMongoExpress(containerName: "express")
    .AddDatabase("database", "Development")
    ;

var api = builder.AddProject<Projects.BumpBuddy_Api>("api")
    .WithHttpHealthCheck("/health")
    .WithReference(mongodb);

Edit:
Went to the aspire source code and got my answer

I added this to my api project:

.WithEnvironment("Database__ConnectionString", mongodb.Resource.ConnectionStringExpression)

.WithEnvironment("Database__ConnectionString", mongodb.Resource.ConnectionStringExpression)

mongodb.Resource.ConnectionStringExpression has the connectionstring.

davidfowl•6/21/25, 2:52 AM

Just pass mongodb

davidfowl•6/21/25, 2:52 AM

It’ll resolve the connection string

Ddavidfowl It’ll resolve the connection string

TeBeCo•6/21/25, 9:59 AM

is there a reason all connection string on aspire not use use options pattern ?

TeBeCo•6/21/25, 9:59 AM

instead of hard coded config section ?

TeBeCo•6/21/25, 10:00 AM

because the client driver will use it post di setup but aspire force the check on the conf hard coded before

TeBeCo•6/21/25, 10:01 AM

and in some case having the option flexibility with .Configure<TFromDi> helps looking at other setup during resolves time, or Validate and have a clear error instead of a null ref

TeBeCo•6/21/25, 10:02 AM

for example if i want a boolean to toggle managed identity or not, this change the connection thing
and i'd rather have the IOption do all that than doing it inside startup with string keys

davidfowl•6/21/25, 2:42 PM

how do you avoid the opinionated configuration?

davidfowl•6/21/25, 2:42 PM

Take redis for example

TeBeCo•6/21/25, 4:03 PM

the stack exchange redis already suffer from the exact same issue

TeBeCo•6/21/25, 4:03 PM

without aspire

TeBeCo•6/21/25, 4:04 PM

issue is that it's now common ground again to be like "hey magic string on config and if/else + custom GetValue"

TeBeCo•6/21/25, 4:05 PM

i'm a bit surprised that it's feeling going back to what was espeically with the associated trouble

TeBeCo•6/21/25, 4:06 PM

but even for driver still stuck is that "legacy way code design" , the aspire setup could also avoir reading the value ahead of time and just push it wherever anyone want it (ie: not having the "integration client" trying to use it in a too eager way as a config/string if the underlying driver don't do need that

TeBeCo•6/21/25, 4:08 PM

i never understood why an infra middleware should hinder app startup

TeBeCo•6/21/25, 4:08 PM

you CAN, if you WANT add some check or have similar things as part of IHostedService / StartAsync if you absolutly need to solve that

davidfowl•6/21/25, 4:08 PM

client integrations support configuration

TeBeCo•6/21/25, 4:09 PM

indeed

TeBeCo•6/21/25, 4:09 PM

configuration

davidfowl•6/21/25, 4:09 PM

https://learn.microsoft.com/en-us/dotnet/aspire/caching/stackexchange-redis-integration?tabs=dotnet-cli&pivots=redis#use-configuration-providers

.NET Aspire Redis integration - .NET Aspire

Learn how to use the .NET Aspire Redis integration, which includes both hosting and client integrations.

TeBeCo•6/21/25, 4:09 PM

i'm absolutly not saying it does not support it

davidfowl•6/21/25, 4:10 PM

what are you saying?

TeBeCo•6/21/25, 4:10 PM

i'm saying it's accessing value before DI setup time (before builder.Build())

TeBeCo•6/21/25, 4:10 PM

which tends to add code for read/validate/parse in some situation when it could just be removed for integration already having Options support

davidfowl•6/21/25, 4:11 PM

I think I'm missing the big picture

TeBeCo•6/21/25, 4:11 PM

IIRC the issue on passwordless setup because there was a null check ?

TeBeCo•6/21/25, 4:11 PM

it's roughtly similar

TeBeCo•6/21/25, 4:12 PM

generally it's possible to do things like:

TeBeCo•6/21/25, 4:12 PM

which helps doing general defaulting or crossover setup

TeBeCo•6/21/25, 4:13 PM

being the "integration" actual Options