ci: lint shell

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

ci/cue.mod/module.cue

@@ -0,0 +1 @@
+module: "github.com/dagger/dagger/ci"

ci/cue.mod/pkg

@@ -0,0 +1 @@
+../../pkg

ci/main.cue

@@ -8,6 +8,8 @@ import (
 	"universe.dagger.io/docker"
 	"universe.dagger.io/go"
 	"universe.dagger.io/go/golangci"
+
+	"github.com/dagger/dagger/ci/pkg/shellcheck"
 )
 
 dagger.#Plan & {
@@ -90,6 +92,10 @@ dagger.#Plan & {
 				version: "1.45"
 			}
 
+			shell: shellcheck.#Lint & {
+				source: _source
+			}
+
 			cue: docker.#Build & {
 				steps: [
 					alpine.#Build & {

ci/pkg/shellcheck/shellcheck.cue

@@ -0,0 +1,34 @@
+package shellcheck
+
+import (
+	"dagger.io/dagger"
+
+	"universe.dagger.io/docker"
+)
+
+#Lint: {
+	// Source code
+	source: dagger.#FS
+
+	// shellcheck version
+	version: *"0.8.0" | string
+
+	_image: docker.#Pull & {
+		source: "koalaman/shellcheck-alpine:v\(version)"
+	}
+
+	container: docker.#Run & {
+		input: _image.output
+		mounts: "source": {
+			dest:     "/src"
+			contents: source
+		}
+		workdir: "/src"
+		command: {
+			name: "sh"
+			args: ["-c", #"""
+				shellcheck $(find . -type f \( -iname \*.bats -o -iname \*.bash -o -iname \*.sh \) -not -path "*/node_modules/*" -not -path "*/bats-*/*")
+				"""#]
+		}
+	}
+}