如何在 AzureDevops 中为 Dockerfile 设置环境变量（ASPNETCORE_ENVIRONMENT）？

Question

I was planning to use Azure Devops to do the CI/CD for my dockerized .NET Core API. My API now have appsettings.json and appsettings.Development.json .

Below are my Dockerfile:

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS base
WORKDIR /app
EXPOSE 80

ENV ASPNETCORE_ENVIRONMENT Development

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /src
COPY ["Api/Api.csproj", "Api/"]
RUN dotnet restore "Api/Api.csproj"
COPY . .
WORKDIR "/src/Api"
RUN dotnet build "Api.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "Api.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "Api.dll", "--environment=Development"]

As can seen, I set the environment at ASPNETCORE_ENVIRONMENT and also the ENTRYPOINT ["dotnet", "Api.dll", "--environment=Development"] . However how can I make it flexible in Azure Devops pipeline?

For example having different environments like development and production . So let say I have another appsettings.Production.json , the project would automatically pick up this file instead of appsettings.Development.json if I set the environment to Production .

Is there anyway to do this or am I understanding this whole flow wrong? Thank you.

Answer 1

Check the answer in this case: Inject env variable into build stage of image

You can set an ARG var_name and reference ENV to the ARG variables. Then you can replace those variables when docker build the image $ docker build --build-arg var_name=$(VARIABLE_NAME)

For example the add ARG in dockerfile, and have the ENV variable refer to it:

ARG SECRET
ENV ASPNETCORE_ENVIRONMENT=$SECRET

You can use dock build task and dock push task separately, as buildandpush command cannot accept arguments. And set a variable SECRET in your pipeline.

The set the Build Arguments SECRET= $(SECRET) to replace the ARG SECRET