Why do we build and publish as two steps when publish also builds?

user_1308645 0
Viewed 1211

Sorry if this is a stupid question, but why does the dockerfile include steps to build and publish when the publish also builds?

The following Dockerfile is created in my web application:

FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 80

FROM microsoft/dotnet:2.1-sdk AS build
WORKDIR /src
COPY ["WebApplication1/WebApplication1.csproj", "WebApplication1/"]
RUN dotnet restore "WebApplication1/WebApplication1.csproj"
COPY . .
WORKDIR "/src/WebApplication1"
RUN dotnet build "WebApplication1.csproj" -c Release -o /app

FROM build AS publish
RUN dotnet publish "WebApplication1.csproj" -c Release -o /app

FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "WebApplication1.dll"]
visual-studio-2017 dockerfile asp.net-core .net c#
3 Answers

According to the book .NET Microservices: Architecture for Containerized .NET Applications (Microsoft EBook), the first build instruction is redundant because the publish instruction also builds, and it is right after the first build instruction. Page 94 (86), line 10.

Here is a short excerpt from the book:

1 FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
2 WORKDIR /app
3 EXPOSE 80
4
5 FROM microsoft/dotnet:2.1-sdk AS build
6 WORKDIR /src
7 COPY src/Services/Catalog/Catalog.API/Catalog.API.csproj …
8 COPY src/BuildingBlocks/HealthChecks/src/Microsoft.AspNetCore.HealthChecks …
9 COPY src/BuildingBlocks/HealthChecks/src/Microsoft.Extensions.HealthChecks …
10 COPY src/BuildingBlocks/EventBus/IntegrationEventLogEF/ …
11 COPY src/BuildingBlocks/EventBus/EventBus/EventBus.csproj …
12 COPY src/BuildingBlocks/EventBus/EventBusRabbitMQ/EventBusRabbitMQ.csproj …
13 COPY src/BuildingBlocks/EventBus/EventBusServiceBus/EventBusServiceBus.csproj …
14 COPY src/BuildingBlocks/WebHostCustomization/WebHost.Customization …
15 COPY src/BuildingBlocks/HealthChecks/src/Microsoft.Extensions …
16 COPY src/BuildingBlocks/HealthChecks/src/Microsoft.Extensions …
17 RUN dotnet restore src/Services/Catalog/Catalog.API/Catalog.API.csproj
18 COPY . .
19 WORKDIR /src/src/Services/Catalog/Catalog.API
20 RUN dotnet build Catalog.API.csproj -c Release -0 /app
21
22 FROM build AS publish
23 RUN dotnet publish Catalog.API.csproj -c Release -0 /app
24
25 FROM base AS final
26 WORKDIR /app
27 COPY --from=publish /app
28 ENTRYPOINT ["dotnet", "Catalog.API.dll"]

For the final optimization, it just happens that line 20 is redundant, as line 23 also builds the application and comes, in essence, right after line 20, so there goes another time-consuming command.

user_13086450

Build is used when we add some reference/service/entities in our code and when partial completed code need to debug . in debug mode every time we need to compile with build when the code is 100% completed it no need to built . directly build by publish.

user_91636230

As noted here, you could also add another stage with tests:

FROM build AS test
WORKDIR /src/Web.test
RUN dotnet test

(between build and publish)

Of course dotnet test also builds the project automatically if it's not already built, but it wouldn't be very readable.
Additionally, dotnet build can also build the whole solution whereas publish only serves one project (as noted here).

user_68412240
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