How deeply does .NET in Action, Second Edition cover Dockerfile instruction?

Defines syntax, base images, copying, startup, caching, and multi-stage builds, but not the full Dockerfile language.

Dockerfile instruction

As explained in .NET in Action, Second Edition

A Dockerfile instruction is a directive written with an instruction keyword and arguments that controls image construction.

A Dockerfile instruction is a directive written as INSTRUCTION arguments that controls image construction. Dockerfiles may contain comments and instructions, and must begin with FROM. FROM selects a base image, which Docker modifies into a new immutable image. section 13.3.1

A practical Dockerfile combines instructions that:

Copy application files with COPY and select the container working directory with WORKDIR. section 13.3.1
Publish network metadata with EXPOSE and define startup behavior with ENTRYPOINT. section 13.3.1
Build applications in separate stages with RUN and COPY --from, producing a smaller runtime image. section 13.3.1

Listing 13.2 Dockerfile for AsciiArtSvc

# Use the official .NET 6 container
FROM mcr.microsoft.com/dotnet/sdk:6.0
  
# Copy files from the current folder on your machine to
# the /src folder in the container
COPY . /src
  
# Set working directory in the container
WORKDIR /src
  
# Expose HTTP port from "docker" launch profile
EXPOSE 5101
  
# Run the application when the container is started
ENTRYPOINT ["dotnet", "run", "--launch-profile", "docker"]

A complete Dockerfile shows base-image selection, file copying, working-directory configuration, port exposure, and application startup. section 13.3.1

Multi-stage image construction

A build stage runs dotnet publish into /publish. A second ASP.NET runtime stage copies that output, exposes port 80, and starts AsciiArtSvc.dll with ENTRYPOINT. section 13.3.1

How .NET in Action, Second Edition covers it

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Also explained in

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Learn Docker in a Month of Lunches, Second EditionA Dockerfile instruction is a declarative directive that specifies a build action or image metadata.
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Kubernetes in Action, Second EditionA Dockerfile instruction is a declarative command that specifies one step in building a container image.

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Related concepts

Dockerfilepart of · A Dockerfile is a text file containing declarative instructions for building a container image and specifying its contents and runtime metadata.
image layerproduces · An image layer is an immutable filesystem change set that contributes to a layered container image and may be stored, cached, or shared independently.
healthcheck instructionincludes · The HEALTHCHECK instruction is a Dockerfile instruction that defines a command and scheduling parameters for testing an application's health in a container.
build cacheconfigures · A build cache is a storage mechanism that preserves completed build-task outputs for reuse when the relevant inputs have not changed.
commandcontrasts with · A command is an instruction or request representing an operation for a system or component to interpret, handle, or execute.
copy instructionincludes · The Dockerfile COPY instruction copies files or directories from a build context or another build stage into an image’s filesystem.

This explainer was generated by Manning's knowledge graph from the text of .NET in Action, Second Edition. The section links point to the parts of the book it draws on.