ci: implemented go lint

Signed-off-by: Sam Alba <samalba@users.noreply.github.com>

ci/base.cue

@@ -5,6 +5,7 @@ import (
 )
 
 let GoVersion = "1.17"
+let GolangCILintVersion = "1.44.0"
 
 // Base container images used for the CI
 images: {
@@ -31,4 +32,14 @@ images: {
 			},
 		]
 	}
+
+	// base image for the Go linter
+	// https://golangci-lint.run/usage/install/#docker
+	goLinter: docker.#Build & {
+		steps: [
+			docker.#Pull & {
+				source: "index.docker.io/golangci/golangci-lint:v\(GolangCILintVersion)"
+			},
+		]
+	}
 }

ci/main.cue

@@ -3,9 +3,7 @@ package main
 import (
 	"strings"
 
-	// "dagger.io/dagger"
 	"dagger.io/dagger/engine"
-
 	"universe.dagger.io/bash"
 )
 
@@ -35,6 +33,12 @@ engine.#Plan & {
 			id: "go mod cache"
 		}
 
+		source: "dagger source code": {
+			contents: inputs.directories.source.contents
+			dest:     "/usr/src/dagger"
+		}
+
+		// FIXME: build only if the linter passed
 		build: bash.#Run & {
 			input: images.goBuilder.output
 
@@ -54,10 +58,7 @@ engine.#Plan & {
 				"""#
 
 			mounts: {
-				"dagger source code": {
+				source
-					contents: inputs.directories.source.contents
-					dest:     "/usr/src/dagger"
-				}
 
 				"go mod cache": {
 					dest:     "/gomodcache"
@@ -68,5 +69,16 @@ engine.#Plan & {
 			workdir: mounts["dagger source code"].dest
 			export: directories: "/build": _
 		}
+
+		goLint: bash.#Run & {
+			input: images.goLinter.output
+
+			// FIXME: the source volume is too slow, taking >3m on docker for mac (vs < 2sec on the host machine)
+			script: contents: "golangci-lint run -v --timeout 5m"
+			workdir: mounts["dagger source code"].dest
+			mounts: {
+				source
+			}
+		}
 	}
 }