README: document install, prerequists and list-images

README.md

@@ -2,6 +2,98 @@
 
 Build images from the commandline in a convenient way.
 
+## Installation
+
+This project is under development right now and needs to be run via:
+```console
+$ go run github.com/osbuild/image-builder-cli/cmd/image-builder@main
+```
+or install it into $GOPATH/bin
+```console
+$ go install github.com/osbuild/image-builder-cli/cmd/image-builder@main
+```
+
+we plan to provide rpm packages as well.
+
+
+## Prerequisites
+
+Make sure to have the required `osbuild` rpms installed:
+```console
+$ sudo dnf install osbuild osbuild-depsolve-dnf osbuild-composer
+```
+(`osbuild-composer` is only needed to get the repository definitions
+and this dependency will go away soon).
+
+## Example
+
+To see the list of buildable images run:
+```console
+$ image-builder list-images
+...
+centos-9 type:qcow2 arch:x86_64
+...
+rhel-10.0 type:ami arch:x86_64
+...
+```
+
+It is possible to filter:
+```console
+$ image-builder list-images --filter ami
+...
+centos-9 type:ami arch:x86_64
+...
+rhel-8.5 type:ami arch:aarch64
+...
+rhel-10.0 type:ami arch:aarch64
+```
+or be more specific
+```console
+$ image-builder list-images --filter "arch:x86*" --filter "distro:*centos*"
+centos-9 type:ami arch:x86_64
+...
+centos-9 type:qcow2 arch:x86_64
+...
+```
+
+The following filters are currently supported, shell-style globbing is supported:
+ * distro: the distro name (e.g. fedora-41)
+ * arch: the architecture name (e.g. x86_64)
+ * type: the image type name (e.g. qcow2)
+ * bootmode: the bootmode (legacy, uefi, hybrid)
+
+The output can also be switched, supported are "text", "json":
+```console
+$ image-builder list-images --output=json
+[
+  {
+    "distro": {
+      "name": "centos-9"
+    },
+    "arch": {
+      "name": "aarch64"
+    },
+    "image_type": {
+      "name": "ami"
+    }
+  },
+...
+  {
+    "distro": {
+      "name": "rhel-10.0"
+    },
+    "arch": {
+      "name": "x86_64"
+    },
+    "image_type": {
+      "name": "wsl"
+    }
+  }
+]
+
+```
+
+
 ## FAQ
 
 Q: Does this require a backend.