Initial merge of faas-containerd

This patch completes part of the work in #20 by porting the code
for faas-containerd in-tree. When tested, I was able to deploy
and then remove figlet from the store on `x86_64`.

In a follow-up PR, duplication will be removed where possible
and consolidated with updated documentation.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

pkg/provider/config/read_test.go

@@ -0,0 +1,107 @@
+package config
+
+import (
+	"strconv"
+	"testing"
+)
+
+type EnvBucket struct {
+	Items map[string]string
+}
+
+func NewEnvBucket() EnvBucket {
+	return EnvBucket{
+		Items: make(map[string]string),
+	}
+}
+
+func (e EnvBucket) Getenv(key string) string {
+	return e.Items[key]
+}
+
+func (e EnvBucket) Setenv(key string, value string) {
+	e.Items[key] = value
+}
+
+func Test_SetSockByEnv(t *testing.T) {
+	defaultSock := "/run/containerd/containerd.sock"
+	expectedSock := "/non/default/value.sock"
+	env := NewEnvBucket()
+	_, config, err := ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.Sock != defaultSock {
+		t.Fatalf("expected %q, got %q", defaultSock, config.Sock)
+	}
+
+	env.Setenv("sock", expectedSock)
+	_, config, err = ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.Sock != expectedSock {
+		t.Fatalf("expected %q, got %q", expectedSock, config.Sock)
+	}
+}
+
+func Test_SetServiceTimeout(t *testing.T) {
+	defaultTimeout := "1m0s"
+
+	env := NewEnvBucket()
+	config, _, err := ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.ReadTimeout.String() != defaultTimeout {
+		t.Fatalf("expected %q, got %q", defaultTimeout, config.ReadTimeout)
+	}
+
+	if config.WriteTimeout.String() != defaultTimeout {
+		t.Fatalf("expected %q, got %q", defaultTimeout, config.WriteTimeout)
+	}
+
+	newTimeout := "30s"
+	env.Setenv("service_timeout", newTimeout)
+	config, _, err = ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.ReadTimeout.String() != newTimeout {
+		t.Fatalf("expected %q, got %q", newTimeout, config.ReadTimeout)
+	}
+
+	if config.WriteTimeout.String() != newTimeout {
+		t.Fatalf("expected %q, got %q", newTimeout, config.WriteTimeout)
+	}
+}
+
+func Test_SetPort(t *testing.T) {
+	defaultPort := 8081
+
+	env := NewEnvBucket()
+	config, _, err := ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.TCPPort == nil {
+		t.Fatal("expected non-nil TCPPort")
+	}
+	if *config.TCPPort != defaultPort {
+		t.Fatalf("expected %d, got %d", defaultPort, config.TCPPort)
+	}
+
+	newPort := 9091
+	newPortStr := strconv.Itoa(newPort)
+	env.Setenv("port", newPortStr)
+	config, _, err = ReadFromEnv(env)
+	if err != nil {
+		t.Fatalf("unexpected error %s", err)
+	}
+	if config.TCPPort == nil {
+		t.Fatal("expected non-nil TCPPort")
+	}
+	if *config.TCPPort != newPort {
+		t.Fatalf("expected %d, got %d", newPort, config.TCPPort)
+	}
+}