Upgrades to containerd, fix deprecations upstream

* Fixes upstream deprecations for containerd
* Fixes deprecations in ioutil package usage
* Break out separate files for function handlers
* Upgrades containerd to 1.7.22
* Fixes default namespace functionality
* Pre-deploy checks as per license agreement
* Removes extra log messages for payload in HTTP handlers, you
can enable FAAS_DEBUG=1 in the CLI instead to see this from
the client's perspective
* Add additional Google DNS server 8.8.4.4 for functions

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

pkg/connectivity.go

@@ -0,0 +1,36 @@
+package pkg
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// ConnectivityCheck checks if the controller can reach the
+// public Internet via HTTPS.
+// A license is required to use OpenFaaS for Commercial Use.
+func ConnectivityCheck() error {
+	req, err := http.NewRequest(http.MethodGet, "https://checkip.amazonaws.com", nil)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("User-Agent", fmt.Sprintf("openfaas-ce/%s faas-netes", Version))
+
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	if req.Body != nil {
+		defer req.Body.Close()
+	}
+
+	if res.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(res.Body)
+
+		return fmt.Errorf("unexpected status code checking connectivity: %d, body: %s", res.StatusCode, strings.TrimSpace(string(body)))
+	}
+
+	return nil
+}