feat(build/pipelines): add go/covdata pipeline

It leverages a go binary built with coverage instrumentation using
the -cover build flag alongside its coverage data genreated to produce
a statements by functions based report via the go tool covdata.

Signed-off-by: Massimiliano Giovagnoli <massimiliano.giovagnoli@chainguard.dev>

Author: maxgio92

pkg/build/pipelines/go/README.md

@@ -1,9 +1,11 @@
+
 <!-- start:pipeline-reference-gen -->
 # Pipeline Reference
 
 
 - [go/build](#gobuild)
 - [go/bump](#gobump)
+- [go/covdata](#gocovdata)
 - [go/install](#goinstall)
 
 ## go/build
@@ -19,7 +21,7 @@ Run a build using the go compiler
 | buildmode | false | The -buildmode flag value. See "go help buildmode" for more information.  | default |
 | deps | false | space separated list of go modules to update before building. example: github.com/foo/bar@v1.2.3  |  |
 | experiments | false | A comma-separated list of Golang experiment names (ex: loopvar) to use when building the binary.  |  |
-| extra-args | false | A space-separated list of extra arguments for go build command.  |  |
+| extra-args | false | A space-separated list of extra arguments to pass to the go build command.  |  |
 | go-package | false | The go package to install  | go |
 | install-dir | false | Directory where binaries will be installed  | bin |
 | ldflags | false | List of [pattern=]arg to append to the go compiler with -ldflags |  |
@@ -49,6 +51,17 @@ Bump go deps to a certain version
 | tidy | false | Run go mod tidy command before and after the bump | true |
 | tidy-compat | false | Set the go version for which the tidied go.mod and go.sum files should be compatible |  |
 
+## go/covdata
+
+Get coverage data with the covdata go tool
+
+### Inputs
+
+| Name | Required | Description | Default |
+| ---- | -------- | ----------- | ------- |
+| cover-dir | false | The GOCOVERDIR path where coverage data files have been generated. It's required to be set as environment variable as well before running the Go binary. | /home/build |
+| package | false | The go package to install | go |
+
 ## go/install
 
 Run a build using the go compiler
@@ -71,4 +84,4 @@ Run a build using the go compiler
 | version | false | Package version to install. This can be a version tag (v1.0.0), a commit hash or another ref (eg latest or HEAD).  |  |
 
 
-<!-- end:pipeline-reference-gen -->
+<!-- end:pipeline-reference-gen -->

pkg/build/pipelines/go/covdata.yaml

@@ -0,0 +1,20 @@
+name: Get coverage data with the covdata go tool
+
+# Leave go off here, some packages pin to an older version. Let's just assume this gets injected elsewhere.
+needs:
+  packages:
+    - ${{inputs.package}}
+    - busybox
+
+inputs:
+  package:
+    description: The go package to install
+    default: go
+  cover-dir:
+    description: The GOCOVERDIR path where coverage data files have been generated. It's required to be set as environment variable as well before running the Go binary.
+    default: /home/build
+
+pipeline:
+  - runs: |
+      cov=$(go tool covdata func -i ${{inputs.cover-dir}}  | tail -1 | awk '{print $NF}' | sed 's|%||g')
+      echo "Statements coverage: ${cov}%"