support and describe building static binaries

README.md

@@ -42,7 +42,7 @@ As seems to be the case for many things in the XMLish world, the xmldsig and xml
 
 This package uses cgo to wrap libxmlsec. As such, you'll need libxmlsec headers and a C compiler to make it work. On linux, this might look like:
 
-    $ apt-get install libxml2-dev libxmlsec1-dev
+    $ apt-get install libxml2-dev libxmlsec1-dev pkg-config
     $ go get github.com/crewjam/go-xmlsec
 
 On Mac with homebrew, this might look like:
@@ -50,4 +50,46 @@ On Mac with homebrew, this might look like:
     $ brew install libxmlsec1 libxml2 pkg-config
     $ go get github.com/crewjam/go-xmlsec
 
+# Static Linking
+
+It may annoy you to grow a depenency on the shared libraries for libxmlsec, libxml2, etc. After some fighting, here is what I made work on Linux to get
+a static binary. See also `Dockerfile.build-static` which build the example
+program using this method.
+
+## Compile libxml
+
+```
+curl -sL ftp://xmlsoft.org/libxml2/libxml2-2.9.4.tar.gz | tar -xzf -
+cd /libxml2-2.9.4
+./configure --enable-static --disable-shared --without-gnu-ld --with-c14n --without-catalog --without-debug --without-docbook  --without-fexceptions  --without-ftp --without-history --without-html --without-http --without-iconv --without-icu --without-iso8859x --without-legacy --without-mem-debug --without-minimum --with-output --without-pattern --with-push --without-python --without-reader --without-readline --without-regexps --without-run-debug --with-sax1 --without-schemas --without-schematron --without-threads --without-thread-alloc --with-tree --without-valid --without-writer --without-xinclude --without-xpath --with-xptr --without-modules --without-zlib --without-lzma --without-coverage
+make install
+```
+
+## Compile openssl
+
+```
+curl -sL ftp://ftp.openssl.org/source/openssl-1.0.2h.tar.gz | tar -xzf -
+cd openssl-1.0.2h
+./config no-shared no-weak-ssl-ciphers no-ssl2 no-ssl3 no-comp no-idea no-dtls no-hw no-threads no-dso
+make install
+```
+
+## Compile libxmlsec
+
+```
+curl -sL http://www.aleksey.com/xmlsec/download/xmlsec1-1.2.22.tar.gz | tar -xzf -
+./configure --enable-static --disable-shared --disable-crypto-dl --disable-apps-crypto-dl --enable-static-linking --without-gnu-ld       --with-default-crypto=openssl --with-openssl=/usr/local/ssl --with-libxml=/usr/local --without-nss --without-nspr --without-gcrypt --without-gnutls --without-libxslt
+make -C src install
+make -C include install
+make install-pkgconfigDATA
+```
+
+## Build with static tag
+
+```
+go build -tags static -ldflags '-s -extldflags "-static"' -o /bin/xmldsig-static.bin ./examples/xmldsig.go
+```
+
+Running `ldd` on the output should produce `not a dynamic executable`.
+