Documentation about middlewares seems to be incorrect

[lvyyljn]

I'm currently working on updating the response from downstream and noticed some inconsistency
As it's stated here https://ocelot.readthedocs.io/en/latest/features/middlewareinjection.html
Obviously you can just add middleware as normal before the call to app.UseOcelot() It cannot be added after as Ocelot does not call the next middleware.

And it's not true, as the last middleware in the BuildOcelotPipeline method is HttpRequesterMiddleware that calls the next middleware, I think documentation should be changed

Specifications

• Version: 18.0.0
• Platform: .NET 6.0

[raman-m]

Hi lvyyljn!
Thanks for your interest in Ocelot!

Specifications

• Version: 18.0.0
• Platform: .NET 6.0

Why do you use previous version? Your project is based on .NET 6 ?
It is time to upgrade to .NET 7 and Ocelot 19.0.2.

[lvyyljn]

Hi @raman-m, it was predefined before me to use .NET 6, so we have to use 18.0.0, would be glad to update but still)
For the 19.0.2 documentation to looks outdated

[raman-m]

What is your real name?
Where are you from?
Why is your GitHub profile empty?

[lvyyljn]

Is this relevant?)
I am only concerned about documentation being outdated,
My name is Denys and I am from Ukraine, my profile is empty as it's first time I need to create issue here

[raman-m]

@lvyyljn commented on 2023-08-29 at 07:39:

I'm currently working on updating the response from downstream and noticed some inconsistency
As it's stated here https://ocelot.readthedocs.io/en/latest/features/middlewareinjection.html
Obviously you can just add middleware as normal before the call to app.UseOcelot() It cannot be added after as Ocelot does not call the next middleware.

We have most actual docs in the repo: Middleware Injection and Overrides | Ocelot/docs/features/middlewareinjection.rst at develop · ThreeMammals/Ocelot
It is better to share the links of the repo.
So, the text we are discussing is here: docs/features/middlewareinjection.rst | Lines 40-41

---

Obviously you can just add middleware as normal before the call to app.UseOcelot()

It says actually that develop should add all custom middlewares and after that developer should call UseOcelot. The argument of this method should be configuration object.

---

It cannot be added after as Ocelot does not call the next middleware.

It says you cannot configure the pipeline after Ocelot's builder has ran. It is correct.
Tom explains here the reason which is Ocelot does not call the next middleware. This reason is strange. And it looks like incomplete...
But I believe after changing to Ocelot does not call the next middleware configuration. it should become 100% correct.

[lvyyljn]

@raman-m thanks for quick response, few questions

It says you cannot configure the pipeline after Ocelot's builder has ran.

You mean here the Ocelot's pipeline correct?
And maybe better would be

Next called middlewares won't affect Ocelot configuration

Maybe I misunderstood something?

[raman-m]

@lvyyljn commented on Aug 28:

And it's not true, as the last middleware in the BuildOcelotPipeline method is HttpRequesterMiddleware that calls the next middleware, I think documentation should be changed

Why would you like to discuss the internal HttpRequesterMiddleware ? It is a part of pipeline but it is private and cannot be overridden because this middleware is not user's one!
From other side, yes, this is the last middleware in overall Ocelot & ASP.NET pipeline, but it serves non-user operation.
The last user middleware which can be overridden is: PreQueryStringBuilderMiddleware being read from pipeline configuration object (pipelineConfiguration).
In general the docs says that PreQueryStringBuilderMiddleware is the last user middleware! And there are no another user middlewares in pipeline.

You seem to be confused about the distinction between system (private) and user (public) middleware. And yes, the docs can be somehow corrected to eliminate this confusion.

[raman-m]

@lvyyljn commented on 2023-08-29 at 08:14:

Maybe I misunderstood something?

Yes, you did.

---

And maybe better would be "Next called middlewares won't affect Ocelot configuration"

Denys, you are welcome to open PR!

[lvyyljn]

@raman-m Totally agree with you on the private and public, and I don't intend to override any of the private middlewares
I wanted to add middleware after UseOcelot, and was confused as the documentation stated Ocelot doesn't call the next middleware

[raman-m]

I cannot get you!...
What does it mean "to add middleware after UseOcelot"?!
The UseOcelot method runs the pipeline builder which builds ASP.NET pipeline. I guess it is impossible to change middlewares chain in run-time.
After building & running ASP.NET pipeline it cannot be changed. It remains unchanged till the next app restart based on pipeline configuration.
We are discussing the docs, not exotic feature, right?...
Are you going to correct the docs or not?

[lvyyljn]

Yes, you're right UseOcelot builds a pipeline, but the build method underhood doesn't close to the ability to edit the pipeline further, it's just a checkpoint, You can try it on a local machine with a few minutes of your time, this code works fine without any error

app.UseSwaggerForOcelotUI(opt =>
{
    opt.PathToSwaggerGenerator = "/swagger/docs";
    opt.ReConfigureUpstreamSwaggerJson = AlterUpstream.AlterUpstreamSwaggerJson;
}).UseOcelot().Wait();

app.UseMiddleware<RequestCultureMiddleware>();

And no, I won't create a PR for docs

[raman-m]

@lvyyljn commented on Aug 29

👌 You've investigated that a custom middleware can be attached after building pipeline. Great! But it is configuration stage during app startup.

You can do any Ocelot research you like.

[raman-m]

@lvyyljn commented on Aug 29

And no, I won't create a PR for docs

FYI
Your issue-question will be closed by #1678
I have added all results of this discussion to mentioned PR. See the commit bd19513