diff --git a/args.go b/args.go
index 96867e0..4b3b79b 100644
--- a/args.go
+++ b/args.go
@@ -6,6 +6,9 @@ import (
 	"git.xdrm.io/go/nix-amer/internal/instruction"
 )
 
+// GetArgs manages cli arguments to build executionContext,
+// extract the buildfile path and return whether to dry-run/execute
+// + adds error information
 func GetArgs() (*instruction.ExecutionContext, string, bool, error) {
 	setupFlags(flag.CommandLine)
 
diff --git a/internal/buildfile/errors.go b/internal/buildfile/errors.go
index 92eaa70..1e54941 100644
--- a/internal/buildfile/errors.go
+++ b/internal/buildfile/errors.go
@@ -5,11 +5,13 @@ import (
 	"git.xdrm.io/go/nix-amer/internal/clifmt"
 )
 
+// LineError wraps errors with a line index
 type LineError struct {
 	Line int
 	Err  error
 }
 
+// Error implements Error
 func (le LineError) Error() string {
 	return fmt.Sprintf(":%d %s", le.Line, clifmt.Color(31, le.Err.Error()))
 }
diff --git a/internal/buildfile/reader.go b/internal/buildfile/reader.go
index 5d3fba3..510f36a 100644
--- a/internal/buildfile/reader.go
+++ b/internal/buildfile/reader.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 )
 
+// ErrNullContext is raised when the given context is nil
 var ErrNullContext = errors.New("null context")
 
 // Reader is the buildfile reader
diff --git a/internal/cnf/loader.go b/internal/cnf/loader.go
index 808017f..18ecb25 100644
--- a/internal/cnf/loader.go
+++ b/internal/cnf/loader.go
@@ -8,7 +8,10 @@ import (
 	"path/filepath"
 )
 
+// ErrUnknownExtension is raised when encountering an unknown extension
 var ErrUnknownExtension = errors.New("unknown extension format")
+
+// ErrUnknownFormat is raised when the format cannot be guessed from the content of the file
 var ErrUnknownFormat = errors.New("cannot infer format from content")
 
 // Load the current file and create the configuration format accordingly
diff --git a/internal/instruction/cnf.go b/internal/instruction/cnf.go
index c8069ea..b006c5f 100644
--- a/internal/instruction/cnf.go
+++ b/internal/instruction/cnf.go
@@ -7,7 +7,9 @@ import (
 	"strings"
 )
 
-var ErrImpossible = fmt.Errorf("cannot update configuration")
+// ErrCannotSet is raised when there is an error trying to update
+// a field
+var ErrCannotSet = fmt.Errorf("cannot set the field")
 
 type config struct {
 	raw string
@@ -63,7 +65,7 @@ func (d config) Exec(ctx ExecutionContext) ([]byte, error) {
 
 	// 2. try to update value
 	if !format.Set(d.Path, d.Value) {
-		return nil, ErrImpossible
+		return nil, ErrCannotSet
 	}
 
 	// 3. Update file
diff --git a/internal/instruction/common.go b/internal/instruction/common.go
index 486c47c..f0b6ccc 100644
--- a/internal/instruction/common.go
+++ b/internal/instruction/common.go
@@ -16,6 +16,7 @@ type T interface {
 	Exec(ExecutionContext) ([]byte, error)
 }
 
+// ExecutionContext contains system-specific drivers to manage the host
 type ExecutionContext struct {
 	PackageManager pkg.PackageManager
 	ServiceManager ser.ServiceManager
diff --git a/internal/instruction/errors.go b/internal/instruction/errors.go
index 64eaf45..0eeb111 100644
--- a/internal/instruction/errors.go
+++ b/internal/instruction/errors.go
@@ -4,5 +4,9 @@ import (
 	"errors"
 )
 
+// ErrInvalidSyntax is raised when encountering an invalid token
 var ErrInvalidSyntax = errors.New("invalid instruction format")
+
+// ErrUnknownInstruction is raised when encountering an unknown instruction
+// it can mean that you're not using the right version or that you've misspelled it
 var ErrUnknownInstruction = errors.New("unknown instruction")
diff --git a/internal/pkg/common.go b/internal/pkg/common.go
index 00c86be..54c6b27 100644
--- a/internal/pkg/common.go
+++ b/internal/pkg/common.go
@@ -1,5 +1,6 @@
 package pkg
 
+// DefaultManager if not empty is the default package-manager to use when missing
 var DefaultManager = ""
 
 // PackageManager is the common interface for all package-manager drivers (e.g. `dpkg` for debian-based, `pacman` for arch)
diff --git a/internal/pkg/loader.go b/internal/pkg/loader.go
index 7b0c01f..63e8b26 100644
--- a/internal/pkg/loader.go
+++ b/internal/pkg/loader.go
@@ -4,9 +4,15 @@ import (
 	"errors"
 )
 
+// ErrUnknownManager is raised when the asked manager does not exist
 var ErrUnknownManager = errors.New("unknown package manager")
+
+// ErrNotInstalled is raised when the candidate package manager is not installed
+// on the host system (use command-line -dry-run to avoid execution errors and just
+// check your buildfile syntax)
 var ErrNotInstalled = errors.New("no candidate installed")
 
+// Load a specific package-manager by its name
 func Load(_manager string) (PackageManager, error) {
 
 	// 1. create manager (fail if unknown)
diff --git a/internal/ser/common.go b/internal/ser/common.go
index dfe1e72..5def149 100644
--- a/internal/ser/common.go
+++ b/internal/ser/common.go
@@ -1,5 +1,6 @@
 package ser
 
+// DefaultManager if not empty is the default service-manager to use when missing
 var DefaultManager = "systemd"
 
 // ServiceManager is the common interface for service managers (systemd, init.d)
diff --git a/internal/ser/errors.go b/internal/ser/errors.go
index ebd6cf8..037726b 100644
--- a/internal/ser/errors.go
+++ b/internal/ser/errors.go
@@ -4,4 +4,5 @@ import (
 	"errors"
 )
 
+// ErrUnknownAction is raised when an unknown action is called (enable, start, ...)
 var ErrUnknownAction = errors.New("unknown action")
diff --git a/internal/ser/loader.go b/internal/ser/loader.go
index 31636bb..99a15d7 100644
--- a/internal/ser/loader.go
+++ b/internal/ser/loader.go
@@ -4,16 +4,22 @@ import (
 	"errors"
 )
 
+// ErrUnknownManager is raised when the asked manager does not exist
 var ErrUnknownManager = errors.New("unknown service manager")
-var ErrNotInstalled = errors.New("not candidate installed")
 
+// ErrNotInstalled is raised when the candidate service manager is not installed
+// on the host system (use command-line -dry-run to avoid execution errors and just
+// check your buildfile syntax)
+var ErrNotInstalled = errors.New("no candidate installed")
+
+// Load a specific service-manager by its name
 func Load(_manager string) (ServiceManager, error) {
 
 	// 1. create manager (fail if unknown)
 	var manager ServiceManager
 	switch _manager {
 	case "systemd":
-		manager = new(Systemd)
+		manager = new(systemd)
 	default:
 		return nil, ErrUnknownManager
 	}
diff --git a/internal/ser/systemd.go b/internal/ser/systemd.go
index 0b9e8ed..c20ab04 100644
--- a/internal/ser/systemd.go
+++ b/internal/ser/systemd.go
@@ -4,14 +4,14 @@ import (
 	"os/exec"
 )
 
-type Systemd struct{}
+type systemd struct{}
 
 // available actions
 var actions = []string{"enable", "disable", "start", "stop", "reload", "restart"}
 
-func (d Systemd) Name() string { return "systemctl" }
+func (d systemd) Name() string { return "systemctl" }
 
-func (d Systemd) Exec(action, service string) error {
+func (d systemd) Exec(action, service string) error {
 
 	// 1. fail if unknown action
 	known := false