How to deploy a different host.json for a different deployment profile?

Question

I deploy my Azure Function from Visual Studio, and as part of my Functions project I have a host.json file which specifies some settings which I need to change for Production vs Development. (Specifically, the extensions:queues:batchSize setting). The reason is unfortunately largely beyond my control (the database I use in development is lower-tier than the production one and higher batch sizes will cause it to fall over pretty quickly).

I'd like to be able to specify a small batch size for development and higher batch size for production. I have production and development deployment profiles already, but I don't see any way to vary the host.json file.

Is there 1) a way to do this natively, and/or 2) a better DevOps practice I should be using to make this issue obsolete? I can't use Azure DevOps yet (long story) but perhaps just having separate branches for dev and production would be sufficient?

IMO, if you don't want to create two projects and deploy them to different Function app/slots, separate branches and build pipelines seem the only way. — Jerry Liu, Nov 13 '18 at 04:05
you can just inject the desired value in the host,json file in your release pipeline using a powershell task — Thomas, Nov 13 '18 at 08:59
@Thomas but how would I be able to access the host.json file from the build artifact zip? — Piiinkyy, Jan 18 '19 at 10:02
somehow you will have to unzip it, open the file, change the setting and rezip it before uploading it. — Thomas, Jan 18 '19 at 10:24

score 4 · Answer 1 · answered Jun 01 '19 at 07:18

Another way to do this would be to set environment variables for it. In your case, you could set extensions:queues:batchSize with one like this

AzureFunctionsJobHost__extensions__queues__batchSize

When deploying to azure, this would be an application setting with this name/key

How to deploy a different host.json for a different deployment profile?

1 Answers1