cnitool: generate container id from the netns path, add docs

We shouldn't be creating networks with a blank containerid. Let's
synthesize one from the netns path.

Also, add a basic README.

diff --git a/cnitool/README.md b/cnitool/README.md
new file mode 100644 (file)
index 0000000..0b19560
--- /dev/null
+++ b/cnitool/README.md
@@ -0,0 +1,47 @@
+# cnitool
+
+`cnitool` is a simple program that executes a CNI configuration. It will
+add or remove an interface in an already-created network namespace.
+
+## Example invocation
+First, install cnitool:
+
+```
+go install github.com/containernetworking/cni/cnitool
+```
+
+Then, check out and build the plugins. All commands should be run from this directory.
+```
+git clone https://github.com/containernetworking/plugins.git
+cd plugins
+./build.sh
+```
+
+Create a network configuration
+```
+echo '{"cniVersion":"0.3.1","name":"myptp","type":"ptp","ipMasq":true,"ipam":{"type":"host-local","subnet":"172.16.29.0/24","routes":[{"dst":"0.0.0.0/0"}]}}' | sudo tee /etc/cni/net.d/10-myptp.conf
+```
+
+Create a network namespace. This will be called `testing`:
+
+```
+sudo ip netns add testing
+```
+
+Add the container to the network:
+```
+sudo CNI_PATH=./bin cnitool add myptp /var/run/netns/testing
+```
+
+Test that it works:
+```
+sudo ip -n testing addr
+sudo ip netns exec testing ping -c 1 4.2.2.2
+```
+
+And clean up:
+```
+sudo CNI_PATH=./bin cnitool del myptp /var/run/netns/testing
+sudo ip netns del testing
+```
+

diff --git a/cnitool/cni.go b/cnitool/cnitool.go
similarity index 91%
rename from cnitool/cni.go
rename to cnitool/cnitool.go
index 7252b8c..5f63cb6 100644 (file)
--- a/cnitool/cni.go
+++ b/cnitool/cnitool.go
@@ -15,6 +15,7 @@
 package main
 
 import (
+       "crypto/sha512"
        "encoding/json"
        "fmt"
        "os"
@@ -85,13 +86,21 @@ func main() {
        }
 
        netns := os.Args[3]
+       netns, err = filepath.Abs(netns)
+       if err != nil {
+               exit(err)
+       }
+
+       // Generate the containerid by hashing the netns path
+       s := sha512.Sum512([]byte(netns))
+       containerID := fmt.Sprintf("cnitool-%x", s[:10])
 
        cninet := &libcni.CNIConfig{
                Path: filepath.SplitList(os.Getenv(EnvCNIPath)),
        }
 
        rt := &libcni.RuntimeConf{
-               ContainerID:    "cni",
+               ContainerID:    containerID,
                NetNS:          netns,
                IfName:         "eth0",
                Args:           cniArgs,