Extend wolfi-base documentation. (#1256)

images/wolfi-base/README.md

@@ -13,8 +13,15 @@
 ---
 <!--monopod:end-->
 
-This base image comes with [apk and busybox](https://github.com/wolfi-dev/os/blob/main/wolfi-base.yaml) and starts you
-into the shell, enabling experimentation and a versatile set of usecases. 
+This is the base image for the [Wolfi Linux Distribution](wolfi.dev). It includes a shell and package manager,
+allowing further packages to be installed such as in a Dockerfile. 
+
+This image is a great place to start when exploring Wolfi.
+
+## Image Variants
+
+As Wolfi is a rolling distribution, we only supply the "latest" tag. There are no point releases of
+Wolfi.
 
 ## Get It!
 
@@ -23,3 +30,82 @@ The image is available on `cgr.dev`:
 ```
 docker pull cgr.dev/chainguard/wolfi-base:latest
 ```
+
+## Usage
+
+The image will start in a shell by default:
+
+```
+$ docker run -it cgr.dev/chainguard/wolfi-base
+6d38c9b4f0d9:/# whoami
+root
+6d38c9b4f0d9:/# cat /etc/os-release
+ID=wolfi
+NAME="Wolfi"
+PRETTY_NAME="Wolfi"
+VERSION_ID="20230201"
+HOME_URL="https://wolfi.dev"
+6d38c9b4f0d9:/# exit
+```
+
+You can run commands directly:
+
+```
+$ docker run cgr.dev/chainguard/wolfi-base ps
+PID   USER     TIME  COMMAND
+    1 root      0:00 ps
+```
+
+It's commonly used in Dockerfiles:
+
+```
+$ cat Dockerfile
+FROM cgr.dev/chainguard/wolfi-base
+
+RUN apk update && apk add redis
+
+ENTRYPOINT ["/usr/bin/redis-server"]
+$ docker build -t myredis --progress plain --no-cache .
+#0 building with "desktop-linux" instance using docker driver
+
+#1 [internal] load .dockerignore
+#1 transferring context: 656B done
+#1 DONE 0.0s
+
+#2 [internal] load build definition from Dockerfile
+#2 transferring dockerfile: 144B done
+#2 DONE 0.0s
+
+#3 [internal] load metadata for cgr.dev/chainguard/wolfi-base:latest
+#3 DONE 0.0s
+
+#4 [1/2] FROM cgr.dev/chainguard/wolfi-base
+#4 CACHED
+
+#5 [2/2] RUN apk update && apk add redis
+#5 0.104 fetch https://packages.wolfi.dev/os/aarch64/APKINDEX.tar.gz
+#5 0.702  [https://packages.wolfi.dev/os]
+#5 0.702 OK: 14620 distinct packages available
+#5 0.750 (1/1) Installing redis (7.2.0-r0)
+#5 1.207 OK: 15 MiB in 15 packages
+#5 DONE 1.2s
+
+#6 exporting to image
+#6 exporting layers 0.0s done
+#6 writing image sha256:bde1c89d952e0e0155acb410ee8143b1daf542bd36a6b22c032250633d08bf76 done
+#6 naming to docker.io/library/myredis done
+#6 DONE 0.0s
+
+$ docker run myredis
+1:C 23 Aug 2023 12:04:56.104 * oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
+1:C 23 Aug 2023 12:04:56.104 * Redis version=7.2.0, bits=64, commit=00000000, modified=0, pid=1, just started
+1:C 23 Aug 2023 12:04:56.104 # Warning: no config file specified, using the default config. In order to specify a config file use /usr/bin/redis-server /path/to/redis.conf
+1:M 23 Aug 2023 12:04:56.104 * monotonic clock: POSIX clock_gettime
+1:M 23 Aug 2023 12:04:56.105 * Running mode=standalone, port=6379.
+1:M 23 Aug 2023 12:04:56.105 * Server initialized
+1:M 23 Aug 2023 12:04:56.105 * Ready to accept connections tcp
+```
+
+## Further Reading
+
+The [edu.chainguard.dev](https://edu.chainguard.dev) site contains extensive documentation on [getting started with Wolfi](https://edu.chainguard.dev/open-source/wolfi/overview/).