From b9995395c0453112eff960ca84887339d75852a2 Mon Sep 17 00:00:00 2001
From: Casey Callendrello <casey.callendrello@coreos.com>
Date: Thu, 21 Sep 2017 13:25:57 +0200
Subject: [PATCH] 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.
---
 cnitool/README.md              | 47 ++++++++++++++++++++++++++++++++++
 cnitool/{cni.go => cnitool.go} | 11 +++++++-
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 cnitool/README.md
 rename cnitool/{cni.go => cnitool.go} (91%)

diff --git a/cnitool/README.md b/cnitool/README.md
new file mode 100644
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
--- 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,
-- 
2.44.0