test: unified testimages

Makefile

@@ -43,3 +43,6 @@ integration:
 
 alerting:
 	cd test/integration/alerting && docker build -t securesystemsengineering/alerting-endpoint . && cd -
+
+build-testimage-%:
+	docker build --build-arg="MESSAGE=$*" -t securesystemsengineering/testimage:$* -f test/testdata/dockerfiles/Dockerfile test/testdata/dockerfiles

test/testdata/dockerfiles/Dockerfile

@@ -1,3 +1,18 @@
-FROM alpine:3.18@sha256:eece025e432126ce23f223450a0326fbebde39cdf496a85d8c016293fc851978
-RUN echo "while true; do echo 'Hello World of signing ;)'; sleep 3; done" >> hello.sh
-CMD ["sh", "hello.sh"]
+FROM gcc@sha256:f993601701a37bef71e7f8fc1ef9410b09b15556f4371b06dcc10202cc81f9ea AS builder
+
+ARG MESSAGE
+ENV MESSAGE=$MESSAGE
+
+WORKDIR /
+
+RUN apt update && apt install -y gettext
+
+COPY main.c /main.c
+RUN envsubst < /main.c > /main_.c
+RUN gcc -o /main -static /main_.c
+
+FROM scratch
+
+COPY --from=builder /main /main
+
+ENTRYPOINT ["./main"]

test/testdata/dockerfiles/README.md

@@ -0,0 +1,3 @@
+# Test Images
+
+To build a new test image run `make build-testimage-<tag>`, replacing the `<tag>` with a string of your choice. This will create an image called `securesystemsengineering/testimage:<tag>` which can be pushed and used for testing purposes :tada:

test/testdata/dockerfiles/signed/main.c → test/testdata/dockerfiles/main.c

@@ -1,7 +1,7 @@
 #include <unistd.h>
 #include <sys/syscall.h>
 
-const char message[] = "Signed.\n";
+const char message[] = "$MESSAGE\n";
 
 int main()
 {