README.alpine: add alpine readme

Signed-off-by: John Coyle <[email protected]>

README.alpine.md

@@ -0,0 +1,38 @@
+# Alpine Build (Experimental)
+
+## Dev Env Setup
+
+```
+apk --update add bash sudo git
+git clone https://github.com/ceph/ceph
+```
+
+### Build
+
+```
+./run-make-check.sh -DWITH_EMBEDDED=OFF -DWITH_SYSTEM_BOOST=ON -DWITH_LTTNG=OFF -DWITH_REENTRANT_STRSIGNAL=ON -DWITH_THREAD_SAFE_RES_QUERY=ON
+```
+
+### Packaging
+
+```
+./make-apk.sh
+```
+
+### Docker
+
+```
+cd ceph/src
+
+./test/docker-test.sh --os-type alpine --os-version edge ./make-apk.sh
+
+or
+
+./test/docker-test.sh --os-type alpine --os-version edge -- ./run-make-check.sh -DWITH_EMBEDDED=OFF -DWITH_SYSTEM_BOOST=ON -DWITH_LTTNG=OFF -DWITH_REENTRANT_STRSIGNAL=ON -DWITH_THREAD_SAFE_RES_QUERY=ON
+
+```
+
+## Known Issues
+
+- Uses musl libc malloc because musl does not currently support replacing malloc implementation. see https://bugs.alpinelinux.org/issues/5389
+- No backtrace support need to look at libunwind integration