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Go#

This guide covers configuring Golang projects on Semaphore. If you’re new to Semaphore we recommend reading the Guided tour first.

Hello world#

# .semaphore/semaphore.yml
version: v1.0
name: Go example
agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu1804
blocks:
  - name: Hello world
    task:
      jobs:
        - name: Run Go
          commands:
            - go version

Example project#

Semaphore provides a tutorial and example Go application with a working CI pipeline that you can use to get started quickly:

Supported Go versions#

Semaphore supports all versions of Go. You have the following options:

Linux: Go is available out-of-the-box in the Ubuntu 18.04 VM image.
Docker: use semaphoreci/golang or your own Docker image with the version of Go and other packages that you need.

Follow the links above for details on currently available language versions and additional tools.

Selecting a Go version on Linux#

The Linux VM provides multiple versions of Go. You can switch between them using the sem-version tool.

For example, in your semaphore.yml:

blocks:
  - name: Tests
    task:
      prologue:
        commands:
          - sem-version go 1.12
      jobs:
        - name: Tests
          commands:
            - go version

If the version of Go that you need is not currently available in the Linux VM, we recommend running your jobs in a custom Docker image.

Using GOPATH#

If you are not using Go 1.11 then you will need to prepare the directory structure Go tooling expects. This requires creating $GOPATH/src and cloning your code into the correct directory. This is possible by changing some environment variables and using the existing Semaphore 2.0 toolbox.

# .semaphore/semaphore.yml
version: v1.0
name: Go Example
agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu1804

blocks:
  - name: Test
    task:
      prologue:
        commands:
          - export "SEMAPHORE_GIT_DIR=$(go env GOPATH)/src/github.com/${SEMAPHORE_PROJECT_NAME}"
          - export "PATH=$(go env GOPATH)/bin:${PATH}"
          - mkdir -vp "${SEMAPHORE_GIT_DIR}" "$(go env GOPATH)/bin"
      jobs:
        - name: Test Suite
          commands:
            # Uses the redefined SEMAPHORE_GIT_DIR to clone code into the correct directory
            - checkout
            # Further setup from this point on

Dependency Caching#

Go projects use multiple approaches to dependency management. If you are using dep then the strategy is similar to other projects.

After downloading dep, you should use the cache utility to store and restore the directory you put your source code files, which for the purposes of this document will be named vendor.

You can download and install dep as follows:

curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh

You can initialize the cache as follows:

blocks:
  - name: Warm cache
    task:
      prologue:
        commands:
          # Go project boiler plate
          - export "SEMAPHORE_GIT_DIR=$(go env GOPATH)/src/github.com/${SEMAPHORE_PROJECT_NAME}"
          - export "PATH=$(go env GOPATH)/bin:${PATH}"
          - mkdir -vp "${SEMAPHORE_GIT_DIR}" "$(go env GOPATH)/bin"
          # Dep install db
          - curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
          - checkout
      jobs:
        - name:
          commands:
            - cache restore deps-$SEMAPHORE_GIT_BRANCH-$(checksum Gopkg.lock),deps-$SEMAPHORE_GIT_BRANCH,deps-master
            - dep ensure -v
            - cache store deps-$SEMAPHORE_GIT_BRANCH-$(checksum Gopkg.lock) vendor

After that you can reuse that cache as follows:

blocks:
  - name: Tests
      prologue:
        commands:
          # Go project boiler plate
          - export "SEMAPHORE_GIT_DIR=$(go env GOPATH)/src/github.com/${SEMAPHORE_PROJECT_NAME}"
          - export "PATH=$(go env GOPATH)/bin:${PATH}"
          - mkdir -vp "${SEMAPHORE_GIT_DIR}" "$(go env GOPATH)/bin"
          # Dep install db
          - curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
          - checkout
          - cache restore deps-$SEMAPHORE_GIT_BRANCH-$(checksum Gopkg.lock),deps-$SEMAPHORE_GIT_BRANCH,deps-master
      jobs:
        - name: Suite
          commands:
            - make test