Build from Dockerfile¶
Testcontainers for Go gives you the ability to build an image and run a container from a Dockerfile.
You can do so by specifying a Context
(the filepath to the build context on
your local filesystem) and optionally a Dockerfile
(defaults to "Dockerfile")
like so:
FromDockerfile: FromDockerfile{
Context: "testdata",
Dockerfile: "echo.Dockerfile",
Repo: "test-repo",
Tag: "test-tag",
},
As you can see, you can also specify the Repo
and Tag
optional fields to use for the image. If not passed, the
image will be built with a random name and tag.
If your Dockerfile expects build args:
FROM alpine@sha256:51b67269f354137895d43f3b3d810bfacd3945438e94dc5ac55fdac340352f48
ARG FOO
ba := "build args value"
req := ContainerRequest{
FromDockerfile: FromDockerfile{
Context: filepath.Join(".", "testdata"),
Dockerfile: "args.Dockerfile",
BuildArgs: map[string]*string{
"FOO": &ba,
},
},
ExposedPorts: []string{"8080/tcp"},
WaitingFor: wait.ForLog("ready"),
}
Dynamic Build Context¶
If you would like to send a build context that you created in code (maybe you have a dynamic Dockerfile), you can
send the build context as an io.Reader
since the Docker Daemon accepts it as a tar file, you can use the tar package to create your context.
To do this you would use the ContextArchive
attribute in the FromDockerfile
struct.
var buf bytes.Buffer
tarWriter := tar.NewWriter(&buf)
// ... add some files
if err := tarWriter.Close(); err != nil {
// do something with err
}
reader := bytes.NewReader(buf.Bytes())
fromDockerfile := testcontainers.FromDockerfile{
ContextArchive: reader,
}
Please Note if you specify a ContextArchive
this will cause Testcontainers for Go to ignore the path passed
in to Context
.
Ignoring files in the build context¶
The same as Docker has a .dockerignore
file to ignore files in the build context, Testcontainers for Go also supports this feature.
A .dockerignore
living in the root of the build context will be used to filter out files that should not be sent to the Docker daemon.
The .dockerignore
file won't be sent to the Docker daemon either.
Note
At this moment, Testcontainers for Go does not support Dockerfile-specific .dockerignore
files.
Images requiring auth¶
If you are building a local Docker image that is fetched from a Docker image in a registry requiring authentication
(e.g., assuming you are fetching from a custom registry such as myregistry.com
), Testcontainers for Go will automatically
discover the credentials for the given Docker image from the Docker config, as described here.
req := ContainerRequest{
FromDockerfile: testcontainers.FromDockerfile{
Context: "/path/to/build/context",
Dockerfile: "CustomDockerfile",
},
}
Keeping built images¶
Per default, built images are deleted after being used.
However, some images you build might have no or only minor changes during development.
Building them for each test run might take a lot of time.
You can avoid this by setting KeepImage
in FromDockerfile
.
If the image is being kept, cached layers might be reused during building or even the whole image.
req := ContainerRequest{
FromDockerfile: testcontainers.FromDockerfile{
// ...
KeepImage: true,
},
}
Advanced usage¶
In the case you need to pass additional arguments to the docker build
command, you can use the BuildOptionsModifier
attribute in the FromDockerfile
struct.
This field holds a function that has access to Docker's ImageBuildOptions type, which is used to build the image. You can use this modifier on your own risk to modify the build options with as many options as you need.
c, err := GenericContainer(ctx, GenericContainerRequest{
ContainerRequest: ContainerRequest{
FromDockerfile: FromDockerfile{
Context: "testdata",
Dockerfile: "target.Dockerfile",
KeepImage: false,
BuildOptionsModifier: func(buildOptions *types.ImageBuildOptions) {
buildOptions.Target = "target2"
},
},
},
Started: true,
})
FROM alpine AS target0
CMD ["echo", "target0"]
FROM target0 AS target1
CMD ["echo", "target1"]
FROM target1 AS target2
CMD ["echo", "target2"]