Merge pull request containernetworking#419 from asridharan/cnitool

Added documentation for `cnitool`

Documentation/cnitool.md

@@ -0,0 +1,16 @@
+# Overview
+The `cnitool` is a utility that can be used to test a CNI plugin
+without the need for a container runtime. The `cnitool` takes a
+`network name` and a `network namespace` and a command to `ADD` or
+`DEL`,.i.e, attach or detach containers from a network. The `cnitool`
+relies on the following environment variables to operate properly:
+* `NETCONFPATH`: This environment variable needs to be set to a
+ directory. It defaults to `/etc/cni/net.d`. The `cnitool` searches
+ for CNI configuration files in this directory with the extension
+ `*.conf` or `*.json`. It loads all the CNI configuration files in
+ this directory and if it finds a CNI configuration with the `network
+ name` given to the cnitool it returns the corresponding CNI
+ configuration, else it returns `nil`.
+
+* `CNI_PATH`: For a given CNI configuration `cnitool` will search for
+ the corresponding CNI plugin in this path.

libcni/conf.go

@@ -16,7 +16,6 @@ package libcni
 
 import (
  "encoding/json"
- "errors"
  "fmt"
  "io/ioutil"
  "os"
@@ -33,7 +32,13 @@ func (e NotFoundError) Error() string {
  return fmt.Sprintf(`no net configuration with name "%s" in %s`, e.Name, e.Dir)
 }
 
-var NoConfigsFoundError = errors.New("no net configurations found")
+type NoConfigsFoundError struct {
+ Dir string
+}
+
+func (e NoConfigsFoundError) Error() string {
+ return fmt.Sprintf(`no net configurations found in %s`, e.Dir)
+}
 
 func ConfFromBytes(bytes []byte) (*NetworkConfig, error) {
  conf := &NetworkConfig{Bytes: bytes}
@@ -149,7 +154,7 @@ func LoadConf(dir, name string) (*NetworkConfig, error) {
  case err != nil:
  return nil, err
  case len(files) == 0:
- return nil, NoConfigsFoundError
+ return nil, NoConfigsFoundError{Dir: dir}
  }
  sort.Strings(files)
 
@@ -187,16 +192,12 @@ func LoadConfList(dir, name string) (*NetworkConfigList, error) {
  singleConf, err := LoadConf(dir, name)
  if err != nil {
  // A little extra logic so the error makes sense
- switch {
- // neither configlists nor config files found
- case len(files) == 0 && err == NoConfigsFoundError:
- return nil, err
- // config lists found but no config files found
- case len(files) != 0 && err == NoConfigsFoundError:
+ if _, ok := err.(NoConfigsFoundError); len(files) != 0 && ok {
+ // Config lists found but no config files found
  return nil, NotFoundError{dir, name}
- default: // either not found or parse error
- return nil, err
  }
+
+ return nil, err
  }
  return ConfListFromConf(singleConf)
 }

libcni/conf_test.go

@@ -61,7 +61,7 @@ var _ = Describe("Loading configuration from disk", func() {
 
  It("returns a useful error", func() {
  _, err := libcni.LoadConf(configDir, "some-plugin")
- Expect(err).To(MatchError("no net configurations found"))
+ Expect(err).To(MatchError(libcni.NoConfigsFoundError{Dir: configDir}))
  })
  })
 
@@ -244,7 +244,7 @@ var _ = Describe("Loading configuration from disk", func() {
 
  It("returns a useful error", func() {
  _, err := libcni.LoadConfList(configDir, "some-plugin")
- Expect(err).To(MatchError("no net configurations found"))
+ Expect(err).To(MatchError(libcni.NoConfigsFoundError{Dir: configDir}))
  })
  })