architecture: add OCI cmd diagrams

Create docker example UML flows.

Signed-off-by: Eric Ernst <eric.ernst@intel.com>

arch-images/kata-oci-create.txt

@@ -0,0 +1,31 @@
+Title: Kata Flow
+participant Docker
+participant Kata Runtime
+participant virtcontainers
+participant hypervisor
+participant agent
+participant shim-pod
+participant shim-ctr
+participant proxy
+
+#Docker Create!
+Docker->Kata Runtime: create
+Kata Runtime->virtcontainers: CreateSandbox()
+Note left of virtcontainers: Sandbox\nReady
+virtcontainers->virtcontainers: createNetwork()
+virtcontainers->virtcontainers: Execute PreStart Hooks
+virtcontainers->+hypervisor: Start VM (inside the netns)
+hypervisor-->-virtcontainers: VM started
+virtcontainers->proxy: Start Proxy
+proxy->hypervisor: Connect the VM
+virtcontainers->+agent: CreateSandbox()
+agent-->-virtcontainers: Sandbox Created
+virtcontainers->+agent: CreateContainer()
+agent-->-virtcontainers: Container Created
+virtcontainers->shim-pod: Start Shim
+shim->agent: ReadStdout() (blocking call)
+shim->agent: ReadStderr() (blocking call)
+shim->agent: WaitProcess() (blocking call)
+Note left of virtcontainers: Container\nReady
+virtcontainers-->Kata Runtime: End of CreateSandbox()
+Kata Runtime-->Docker: End of create

arch-images/kata-oci-exec.txt

@@ -0,0 +1,20 @@
+Title: Docker Exec
+participant Docker
+participant kata-runtime
+participant virtcontainers
+participant shim
+participant hypervisor
+participant agent
+participant proxy
+
+#Docker Exec
+Docker->kata-runtime: exec
+kata-runtime->virtcontainers: EnterContainer()
+virtcontainers->agent: exec 
+agent->virtcontainers: Process started in the container
+virtcontainers->shim: start shim
+shim->agent: ReadStdout()
+shim->agent: ReadStderr()
+shim->agent: WaitProcess()
+virtcontainers->kata-runtime: End of EnterContainer()
+kata-runtime-->Docker: End of exec

arch-images/kata-oci-start.txt

@@ -0,0 +1,20 @@
+Title: Docker Start
+participant Docker
+participant Kata Runtime
+participant virtcontainers
+participant hypervisor
+participant agent
+participant shim-pod
+participant shim-ctr
+participant proxy
+
+#Docker Start
+Docker->Kata Runtime: start
+Kata Runtime->virtcontainers: StartSandbox()
+Note left of virtcontainers: Sandbox\nRunning
+virtcontainers->+agent: StartContainer()
+agent-->-virtcontainers: Container Started
+Note left of virtcontainers: Container-pod\nRunning
+virtcontainers->virtcontainers: Execute PostStart Hooks
+virtcontainers-->Kata Runtime: End of StartSandbox()
+Kata Runtime-->Docker: End of start

architecture.md

@@ -176,7 +176,7 @@ For example, when `docker run -ti ubuntu date` is run:
 - The agent will create a new confined context to run the specified command in
   (`date` in this example).
 - The agent will then execute the command (`date` in this example) inside this
-  new context, first setting the root filesystem to the expected Ubuntu* root
+  new context, first setting the root filesystem to the expected Ubuntu\* root
   filesystem.
 
 ##### Initrd image
@@ -286,6 +286,8 @@ container.  In Kata Containers, this is handled as follows:
 
 Now the `exec`'ed process is running within the VM, sharing `uts`, `pid`, `mnt` and `ipc` namespaces with the container process.
 
+![the picture](arch-images/docker-exec.svg)
+
 #### [`kill`](https://github.com/kata-containers/runtime/blob/master/cli/kill.go)
 
 When sending the OCI `kill` command, the container runtime should send a
@@ -347,9 +349,6 @@ process representing this container process.
 	4. Communicate with `kata-agent` (connecting the proxy) to remove the container configuration from the VM.
 4. Return container status.
 
-![CRIO workflow](arch-images/kata-crio-uml.png)
-
-
 ## Proxy
 
 Communication with the VM can be achieved by either `virtio-serial` or, if the host