Dan Čermák
af22e66601
OBS-URL: https://build.opensuse.org/package/show/devel:BCI:Tumbleweed/golang-oldstable-image?expand=0&rev=133
136 lines
4.2 KiB
Markdown
136 lines
4.2 KiB
Markdown
# Go 1.21 development container image
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## Description
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[Go](https://go.dev/) (a.k.a., Golang) is a statically-typed programming
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language, with syntax loosely derived from C. Go offers additional features
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such as garbage collection, type safety, certain dynamic-typing capabilities,
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additional built-in types (for example, variable-length arrays and key-value
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maps) as well as a large standard library.
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## Usage
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We recommend using the Go image as a build environment. Thus,
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the compiler does not need to be shipped as part of the images that are
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deployed. Instead, we recommend to use the Go image as the
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builder image only.
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There are two options to work with Go images. First, you can encapsulate your
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application in a `scratch` container image, essentially an empty filesystem
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image. This approach only works if your Go application does not depend on libc
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or any other library or files, as they will not be available.
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The second option uses a slim base container image with just the minimal
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packages required to run the Go application.
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To compile and deploy an application, copy the sources, fetch dependencies
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(assuming go.mod is used for dependency management), and build the binary using
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the following Dockerfile options.
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### Building from `scratch`
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```Dockerfile
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# Build the application using the Go 1.21 development container image
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FROM registry.opensuse.org/opensuse/bci/golang:1.21 as build
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WORKDIR /app
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# pre-copy/cache go.mod for pre-downloading dependencies and only
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# redownloading them in subsequent builds if they change
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COPY go.mod go.sum ./
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RUN go mod download && go mod verify
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COPY . ./
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# Make sure to build the application with CGO disabled.
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# This will force Go to use some Go implementations of code
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# rather than those supplied by the host operating system.
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# You need this for scratch images as those supporting libraries
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# are not available.
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RUN CGO_ENABLED=0 go build -o /hello
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# Bundle the application into a scratch image
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FROM scratch
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COPY --from=build /hello /usr/local/bin/hello
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CMD ["/usr/local/bin/hello"]
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```
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Build and run the container image:
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```ShellSession
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$ podman build -t my-golang-app .
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$ podman run -it --rm my-golang-app
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```
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There are situations when you don't want to run an application inside a container.
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To compile the application, without running it inside a container instance, use the following command:
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```ShellSession
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$ podman run --rm -v "$PWD":/app:Z -w /app registry.opensuse.org/opensuse/bci/golang:1.21 go build -v
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```
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To run the application tests inside a container, use the following command:
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```ShellSession
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$ podman run --rm -v "$PWD":/app:Z -w /app registry.opensuse.org/opensuse/bci/golang:1.21 go test -v
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```
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### Building from SLE BCI
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The [SLE BCI General Purpose Base Containers](https://opensource.suse.com/bci-docs/documentation/general-purpose-bci/)
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images offer four different options for deployment, depending on your exact requirements.
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```Dockerfile
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# Build the application using the Go 1.21 development Container Image
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FROM registry.opensuse.org/opensuse/bci/golang:1.21 as build
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WORKDIR /app
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# pre-copy/cache go.mod for pre-downloading dependencies and only
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# redownloading them in subsequent builds if they change
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COPY go.mod go.sum ./
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RUN go mod download && go mod verify
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COPY . ./
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RUN go build -o /hello
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# Bundle the application into a scratch image
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FROM registry.suse.com/bci/bci-micro:15.4
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COPY --from=build /hello /usr/local/bin/hello
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CMD ["/usr/local/bin/hello"]
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```
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The above example uses the SLE BCI micro image as the deployment image for
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the resulting application. See the [SLE BCI use with Go
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documentation](https://opensource.suse.com/bci-docs/guides/use-with-golang/)
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for further details.
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## Additional tools
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In addition to the standard SLE BCI development packages, the following tools
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are included in the image:
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- go1.21-race
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- make
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## Licensing
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`SPDX-License-Identifier: MIT`
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This documentation and the build recipe are licensed as MIT.
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The container itself contains various software components under various open source licenses listed in the associated
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Software Bill of Materials (SBOM).
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This image is based on [openSUSE Tumbleweed](https://get.opensuse.org/tumbleweed/).
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