Part 5: Importing

To copy the files for this example ( Part 5 ) run

earthly --artifact github.com/earthly/earthly/examples/tutorial/go:main+part5/part5 ./part5

Examples in Python, JavaScript and Java are at the bottom of this page.

Calling on Targets From Other Earthfiles

So far we've seen how the FROM command in Earthly has the ability to reference another target's image as its base image, like in the case below where the +build target uses the image from the +deps target.

VERSION 0.6
FROM golang:1.15-alpine3.13
WORKDIR /go-workdir

deps:
    COPY go.mod go.sum ./
    RUN go mod download
    # Output these back in case go mod download changes them.
    SAVE ARTIFACT go.mod AS LOCAL go.mod
    SAVE ARTIFACT go.sum AS LOCAL go.sum

build:
    FROM +deps
    COPY main.go .
    RUN go build -o output/example main.go
    SAVE ARTIFACT output/example AS LOCAL local-output/go-example

But FROM also has the ability to import targets from Earthfiles in different directories. Let's say we have a directory structure like this.

.
├── services
|   └── service-one
|       ├── Earthfile (containing +deps)
|       ├── go.mod
|       └── go.sum
├── main.go
└── Earthfile

We can use a target in the Earthfile in /services/service-one from inside the Earthfile in the root of our directory. NOTE: relative paths must use ./ or ../.

./services/service-one/Earthfile

VERSION 0.6
FROM golang:1.15-alpine3.13
WORKDIR /go-workdir

deps:
    COPY go.mod go.sum ./
    RUN go mod download
    # Output these back in case go mod download changes them.
    SAVE ARTIFACT go.mod AS LOCAL go.mod
    SAVE ARTIFACT go.sum AS LOCAL go.sum

./Earthfile

build:
    FROM ./services/service-one+deps
    COPY main.go .
    RUN go build -o output/example main.go
    SAVE ARTIFACT output/example AS LOCAL local-output/go-example

This code tells FROM that there is another Earthfile in the services/service-one directory and that the Earthfile contains a target called +deps. In this case, if we were to run +build Earthly is smart enough to go into the subdirectory, run the +deps target in that Earthfile, and then use it as the base image for +build.

We can also reference an Earthfile in another repo, which works in a similar way. If the reference does not begin with one of /, ./, or ../, then earthly treats it as a repository. See the reference for details.

build:
    FROM github.com/example/project+remote-target
    COPY main.go .
    RUN go build -o output/example main.go
    SAVE ARTIFACT output/example AS LOCAL local-output/go-example

Importing Whole Projects

In addition to importing single targets from other files, we can also import an entire Earthfile with the IMPORT command. This is helpful if there are several targets in a separate Earthfile that you want access to in your current file. It also allows you to create an alias.

VERSION 0.6
IMPORT ./services/service-one AS my_service
FROM golang:1.15-alpine3.13
WORKDIR /go-workdir

build:
    FROM my_service+deps
    COPY main.go .
    RUN go build -o output/example main.go
    SAVE ARTIFACT output/example AS LOCAL local-output/go-example

In this example, we assume there is a ./services/service-one directory that contains its own Earthfile. We import it and then use the AS keyword to give it an alias.

Then, in our +build target we can inherit from any target in the imported Earthfile by passing alias+target-name. In this case the Earthfile in the service directory has a target named +deps.

More Examples

earthly --artifact github.com/earthly/earthly/examples/tutorial/js:main+part5/part5 ./part5

VERSION 0.6
FROM node:13.10.1-alpine3.11
WORKDIR /js-example

build:
    FROM ./services/service-one+deps
    COPY src src
    RUN mkdir -p ./dist && cp ./src/index.html ./dist/
    RUN npx webpack
    SAVE ARTIFACT dist /dist AS LOCAL dist

docker:
    FROM +deps
    ARG tag='latest'
    COPY +build/dist ./dist
    EXPOSE 8080
    ENTRYPOINT ["/js-example/node_modules/http-server/bin/http-server", "./dist"]
    SAVE IMAGE js-example:$tag

earthly --artifact github.com/earthly/earthly/examples/tutorial/java:main+part5/part5 ./part5

VERSION 0.6
FROM openjdk:8-jdk-alpine
RUN apk add --update --no-cache gradle
WORKDIR /java-example

build:
    FROM ./services/service-one+deps
    COPY src src
    RUN gradle build
    RUN gradle install
    SAVE ARTIFACT build/install/java-example/bin AS LOCAL build/bin
    SAVE ARTIFACT build/install/java-example/lib AS LOCAL build/lib

docker:
    COPY +build/bin bin
    COPY +build/lib lib
    ARG tag='latest'
    ENTRYPOINT ["/java-example/bin/java-example"]
    SAVE IMAGE java-example:$tag

earthly --artifact github.com/earthly/earthly/examples/tutorial/python:main+part5/part5 ./part5

VERSION 0.6
FROM python:3
WORKDIR /code

build:
    FROM ./services/service-one+deps
    COPY src src
    SAVE ARTIFACT src /src

docker:
    COPY +deps/wheels wheels
    COPY +build/src src
    COPY requirements.txt ./
    ARG tag='latest'
    RUN pip install --no-index --find-links=wheels -r requirements.txt
    ENTRYPOINT ["python3", "./src/hello.py"]
    SAVE IMAGE python-example:$tag