pkg/skel: missing env var log lines appear in stderr

Previously, the log lines appeared in stdout before the JSON encoding of
the error message.  That would break JSON parsing of stdout.  Instead, we use
stderr for these unstructured logs, consistent with the CNI spec.

diff --git a/skel/skel.go b/skel/skel.go
index 484ef37..bed405c 100644 (file)
--- a/skel/skel.go
+++ b/skel/skel.go
@@ -40,6 +40,7 @@ type CmdArgs struct {
 type dispatcher struct {
        Getenv func(string) string
        Stdin  io.Reader
+       Stderr io.Writer
 }
 
 type reqForCmdEntry map[string]bool
@@ -106,8 +107,7 @@ func (t *dispatcher) getCmdArgsFromEnv() (string, *CmdArgs, error) {
        for _, v := range vars {
                *v.val = t.Getenv(v.name)
                if v.reqForCmd[cmd] && *v.val == "" {
-                       log.Printf("%v env variable missing", v.name)
-                       // TODO: test this logging ^^^  and log to stderr instead of stdout
+                       fmt.Fprintf(t.Stderr, "%v env variable missing\n", v.name)
                        argsMissing = true
                }
        }
@@ -172,6 +172,7 @@ func PluginMain(cmdAdd, cmdDel func(_ *CmdArgs) error) {
        caller := dispatcher{
                Getenv: os.Getenv,
                Stdin:  os.Stdin,
+               Stderr: os.Stderr,
        }
 
        err := caller.pluginMain(cmdAdd, cmdDel)

diff --git a/skel/skel_test.go b/skel/skel_test.go
index 8a69d55..9974c9a 100644 (file)
--- a/skel/skel_test.go
+++ b/skel/skel_test.go
@@ -15,6 +15,7 @@
 package skel
 
 import (
+       "bytes"
        "errors"
        "io"
        "strings"
@@ -47,6 +48,7 @@ var _ = Describe("dispatching to the correct callback", func() {
        var (
                environment     map[string]string
                stdin           io.Reader
+               stderr          *bytes.Buffer
                cmdAdd, cmdDel  *fakeCmd
                dispatch        *dispatcher
                expectedCmdArgs *CmdArgs
@@ -62,9 +64,11 @@ var _ = Describe("dispatching to the correct callback", func() {
                        "CNI_PATH":        "/some/cni/path",
                }
                stdin = strings.NewReader(`{ "some": "config" }`)
+               stderr = &bytes.Buffer{}
                dispatch = &dispatcher{
                        Getenv: func(key string) string { return environment[key] },
                        Stdin:  stdin,
+                       Stderr: stderr,
                }
                cmdAdd = &fakeCmd{}
                cmdDel = &fakeCmd{}
@@ -87,6 +91,7 @@ var _ = Describe("dispatching to the correct callback", func() {
                                Code: 100,
                                Msg:  "required env variables missing",
                        }))
+                       Expect(stderr.String()).To(ContainSubstring(envVar + " env variable missing\n"))
                } else {
                        Expect(err).NotTo(HaveOccurred())
                }
@@ -117,6 +122,23 @@ var _ = Describe("dispatching to the correct callback", func() {
                        Entry("args", "CNI_ARGS", false),
                        Entry("path", "CNI_PATH", true),
                )
+
+               Context("when multiple required env vars are missing", func() {
+                       BeforeEach(func() {
+                               delete(environment, "CNI_NETNS")
+                               delete(environment, "CNI_IFNAME")
+                               delete(environment, "CNI_PATH")
+                       })
+
+                       It("reports that all of them are missing, not just the first", func() {
+                               Expect(dispatch.pluginMain(cmdAdd.Func, cmdDel.Func)).NotTo(Succeed())
+                               log := stderr.String()
+                               Expect(log).To(ContainSubstring("CNI_NETNS env variable missing\n"))
+                               Expect(log).To(ContainSubstring("CNI_IFNAME env variable missing\n"))
+                               Expect(log).To(ContainSubstring("CNI_PATH env variable missing\n"))
+
+                       })
+               })
        })
 
        Context("when the CNI_COMMAND is DEL", func() {