base: add build-static-ioc.sh to musl image.

This script automates building fully statically linked IOCs using the
musl image.

Also document it in the README.

README.md

@@ -151,3 +151,31 @@ default image with older kernels.
 
 It can be obtained directly from the [GitHub
 registry](https://github.com/cnpem/epics-in-docker/pkgs/container/lnls-alpine-3.18-epics-7).
+
+### Building fully static IOCs
+
+Fully static IOCs can be built using the `build-static-ioc.sh` script provided
+by this image. One way to automate this is using a `docker-compose.yml` file
+and running `docker compose up`; the file should have the following contents:
+
+```
+services:
+  build-static-ioc:
+    image: ghcr.io/cnpem/lnls-alpine-3.18-epics-7:v0.10.0-dev
+    volumes:
+      - type: bind
+        source: ./
+        target: /opt/REPOSITORY
+    working_dir: /opt/REPOSITORY
+    command: build-static-ioc.sh REPOSITORY
+```
+
+This will generate a versioned tarball containing the built IOC. For this
+reason, it is recommended to use git repositories with tagged releases.
+Furthermore, the `target` and `working_dir` keys are where the IOC expects to
+be installed, meaning files like `envPaths` will encode this information. If it
+is necessary to install it elsewhere, and building it with different values for
+the keys isn't possible, it will be necessary to edit `envPaths`.
+
+For development, one can set the `SKIP_CLEAN` environment variable (under
+`environment`), to skip the cleanup build steps and speed up rebuilds.

base/build-static-ioc.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+set -ex
+
+IOC=$1
+
+cp /opt/epics/RELEASE configure/
+cat << EOF > configure/CONFIG_SITE.local
+STATIC_BUILD=YES
+FULL_STATIC_BUILD=YES
+USR_LDFLAGS = -static-pie
+EOF
+
+git config --global --add safe.directory $PWD
+
+make_skip() {
+  if [ -z "$SKIP_CLEAN" ]; then
+    make "$@"
+  fi
+}
+
+make_skip distclean
+make
+make_skip clean
+make -C iocBoot
+
+version=$(git describe --tags)
+
+echo $version > $IOC-version
+echo ".git/" > /tmp/globs
+# this trick is done so the resulting tarball has a root $IOC/ directory
+(cd .. && tar caf $IOC/$IOC-${version}.tar.gz -X /tmp/globs $IOC/)
+rm $IOC-version
+
+make_skip distclean

base/musl/Dockerfile

@@ -73,3 +73,5 @@ COPY backport-ipmicomm.patch .
 COPY caputlog-waveform-fix.patch .
 COPY install_modules.sh .
 RUN NEEDS_TIRPC=YES ./install_modules.sh
+
+COPY build-static-ioc.sh /usr/local/bin