Makefiles for Golang
Make is a build automation tool from the late 70’s that’s pretty popular in C and C++ world. Thanks to its age and popularity you can find tons of tutorials and Make is supported on basically every platform out there. I’m going to demonstrate how to set up a basic Makefile for Golang projects that will build, lint and test your code.
Make has a few simple rules that make it powerful, it expects that each task you create will be the name of an output file on disk. This is nice because if a file already exists with the same name as a task then Make will skip doing the work for that task.
Building
For example if you create the following Makefile
below and place it in the root of your project and run make
, you will
see a new hello_world
binary built:
1hello_world:
2 go build -o hello_world main.go
But at this point if you run it again, you’ll see:
1make: 'hello_world' is up to date.
So lets add a clean command to clean up the build output:
1hello_world:
2 go build -o hello_world main.go
3
4clean:
5 rm -rf ./hello_world
One issue here is that the clean
task will only work as long as there isn’t a file in the project also named clean
.
If you want Make to ignore the file system for this task then you can add an entry to the .PHONY
list:
1hello_world:
2 go build -o hello_world main.go
3
4clean:
5 rm -rf ./hello_world
6
7.PHONY: clean
Testing
Next we can run tests. You can define variables in your makefile that run shell commands for their value. I’m running
go list
and filtering out the vendor
folder so we can run tests for every package in our project. Remember to add
that test
task to the .PHONY
list:
1PKGS := $(shell go list ./... | grep -v vendor)
2
3test:
4 go test -v -cover $(PKGS)
5
6.PHONY: test
Linting
Now that we can build and test our code, lets try to lint it. My lint tool of choice is [golangci-lint][golangcilint]
so I like to add an install task that runs go get
to install it. To do this I take advantage of a Make feature called
prerequisite tasks, where you can list tasks that are required to execute before another task runs. This makes it easy
to set up the install task as a dependency of our lint
command, ensuring its installed every time we run it:
1LINT_BIN := $(GOPATH)/bin/golangci-lint
2
3$(LINT_BIN):
4 go get -u github.com/golangci/golangci-lint/cmd/golangci-lint
5
6lint: $(LINT_BIN)
7 @$(LINT_BIN) run -p format -p unused -p bugs # The '@' symbol hides the command in the output
8
9.PHONY: lint
Putting it together
Below is the complete makefile. I added the .SHELLFLAGS
variable, which sets various flags in the shell that Make executes
your commands in. The -euo pipefail
runs your commands in a type of strict mode in Bash which will catch
errors as they happen and make your life debugging shells scripts generally much easier.
1.SHELLFLAGS := -euo pipefail
2PKGS := $(shell go list ./... | grep -v vendor)
3LINT_BIN := $(GOPATH)/bin/golangci-lint
4
5hello_world:
6 go build -o hello_world main.go
7
8lint: $(LINT_BIN)
9 @$(LINT_BIN) run -p format -p unused -p bugs # The '@' symbol hides the command in the output
10
11test:
12 go test -v -cover $(PKGS)
13
14$(LINT_BIN):
15 go get -u github.com/golangci/golangci-lint/cmd/golangci-lint
16
17clean:
18 rm -rf ./hello_world
19
20.PHONY: clean lint test