snap: improve README and Makefile

Address code review of pr #82

fixes #88

Signed-off-by: Julio Montes <julio.montes@intel.com>

.ci/lib.sh

@@ -26,10 +26,10 @@ check_kata_kernel_version(){
 }
 
 install_yq() {
-	GOPATH=${GOPATH:-${HOME}/go}
+	path=$1
-	local yq_path="${GOPATH}/bin/yq"
+	local yq_path=${path}/yq
 	local yq_pkg="github.com/mikefarah/yq"
-	[ -x  "${GOPATH}/bin/yq" ] && return
+	[ -x  "${yq_path}" ] && return
 
 	case "$(arch)" in
 	"aarch64")
@@ -45,7 +45,7 @@ install_yq() {
 		;;
 	esac
 
-	mkdir -p "${GOPATH}/bin"
+	mkdir -p "${path}"
 
 	# Workaround to get latest release from github (to not use github token).
 	# Get the redirection to latest release on github.

Makefile

@@ -7,13 +7,14 @@
 
 MK_DIR :=$(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
 SED := sed
-YQ := $(shell go env GOPATH)/bin/yq
+YQ := $(MK_DIR)/yq
 SNAPCRAFT_FILE := snap/snapcraft.yaml
 VERSIONS_YAML_FILE := versions.yaml
 VERSIONS_YAML_FILE_URL := https://raw.githubusercontent.com/kata-containers/runtime/master/versions.yaml
 VERSION_FILE := VERSION
 VERSION_FILE_URL := https://raw.githubusercontent.com/kata-containers/runtime/master/VERSION
 
+export MK_DIR
 export YQ
 export VERSION_FILE
 export VERSIONS_YAML_FILE
@@ -31,7 +32,7 @@ test-packaging-tools:
 	@$(MK_DIR)/obs-packaging/build_from_docker.sh
 
 $(YQ):
-	@bash -c "source .ci/lib.sh; install_yq"
+	@bash -c "source .ci/lib.sh; install_yq $${MK_DIR}"
 
 $(VERSION_FILE):
 	@curl -sO $(VERSION_FILE_URL)

snap/README.md

@@ -1,9 +1,9 @@
 # Kata Containers snap image
 
-* [Kata Containers snap image](#kata-containers-snap-image)
 * [Initial setup](#initial-setup)
-* [Build snap image](#build-snap-image)
+* [Install snap](#install-snap)
-* [Install snap (developer)](#install-snap-developer)
+* [Build and install snap image](#build-and-install-snap-image)
+* [Configure Kata Containers](#configure-kata-containers)
 * [Integration with docker](#integration-with-docker)
 * [Limitations](#limitations)
 
@@ -18,7 +18,15 @@ This directory contains the resources needed to build the Kata Containers
 $ sudo apt-get install -y snapd snapcraft
 ```
 
-## Build snap image
+## Install snap
+
+You can install Kata Containers from the [snapcraft store][8] or by running the following command:
+
+```sh
+$ sudo snap install kata-containers
+```
+
+## Build and install snap image
 
 Run next command at the root directory of the packaging repository.
 
@@ -26,8 +34,6 @@ Run next command at the root directory of the packaging repository.
 $ make snap
 ```
 
-## Install snap (developer)
-
 To install the resulting snap image, snap must be put in [classic mode][3] and the
 security confinement must be disabled (*--classic*). Also since the resulting snap
 has not been signed the verification of signature must be omitted (*--dangerous*).
@@ -39,7 +45,7 @@ $ sudo snap install --classic --dangerous kata-containers_[VERSION]_[ARCH].snap
 Replace `VERSION` with the current version of Kata Containers and `ARCH` with
 the system architecture.
 
-## Configuring Kata Containers ##
+## Configure Kata Containers
 
 By default Kata Containers snap image is mounted at `/snap/kata-containers` as a
 read-only file system, therefore default configuration file can not be edited.
@@ -52,48 +58,28 @@ $ sudo cp /snap/kata-containers/current/usr/share/defaults/kata-containers/confi
 $ $EDITOR /etc/kata-containers/configuration.toml
 ```
 
-## Integration with docker ##
+## Integration with docker and kubernetes
 
-the path to the runtime provided by the Kata Containers snap image is
+The path to the runtime provided by the Kata Containers snap image is
-`/snap/kata-containers/current/usr/bin/kata-runtime`, this runtime must be added to
+`/snap/kata-containers/current/usr/bin/kata-runtime`. You should use it to
-[dockerd][5] via `systemd` or `dockerd` configuration file.
+run Kata Containers with [docker][9] and [kubernetes][10].
-
-`/etc/systemd/system/docker.service.d/runtime.conf`
-
-```ini
-[Service]
-ExecStart=/usr/bin/dockerd -D --add-runtime kata-runtime=/snap/kata-containers/current/usr/bin/kata-runtime --default-runtime=kata-runtime
-```
-
-or
-
-`/etc/docker/daemon.json`
-
-```json
-{
-	"default-runtime": "kata-runtime",
-	"runtimes": {
-		"kata-runtime": {
-			"path": "/snap/kata-containers/current/usr/bin/kata-runtime"
-		}
-	}
-}
-```
-
-after having added the new runtime, the service must be reloaded and restarted
-
-```
-$ sudo systemctl daemon-reload
-$ sudo systemctl restart docker
-```
 
 ## Limitations
 
 The [miniOS image][2] is not included in the snap image as it is not possible for
-QEMU to open a guest RAM backing store on a read-only filesystem.
+QEMU to open a guest RAM backing store on a read-only filesystem. Fortunately,
+you can start Kata Containers with a Linux initial RAM disk (initrd) that is
+included in the snap image. If you want to use the miniOS image instead of initrd,
+then a new configuration file can be [created](#configuring-kata-containers)
+and [configured][7].
 
 [1]: https://docs.snapcraft.io/snaps/intro
 [2]: https://github.com/kata-containers/documentation/blob/master/architecture.md#root-filesystem-image
 [3]: https://docs.snapcraft.io/reference/confinement#classic
 [4]: https://github.com/kata-containers/runtime
 [5]: https://docs.docker.com/engine/reference/commandline/dockerd
+[6]: https://github.com/kata-containers/documentation/blob/master/install/docker/ubuntu-docker-install.md
+[7]: https://github.com/kata-containers/documentation/blob/master/Developer-Guide.md#configure-to-use-initrd-or-rootfs-image
+[8]: https://snapcraft.io/kata-containers
+[9]: https://github.com/kata-containers/documentation/blob/master/Developer-Guide.md#run-kata-containers-with-docker
+[10]: https://github.com/kata-containers/documentation/blob/master/Developer-Guide.md#run-kata-containers-with-kubernetes