Add a Docker artifact (#61)

In case this might be interesting to anyone, this PR adds a multistage
Dockerfile based on the latest Ubuntu, compiles the project using the
`Makefile` and copies the resulting binary to a new, clean, image.

Dockerfile

@@ -0,0 +1,21 @@
+FROM ubuntu as compiler
+
+RUN apt update
+
+# Install tzdata without being interactive
+RUN ln -fs /usr/share/zoneinfo/America/New_York /etc/localtime
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tzdata
+
+# Tools to compile:
+RUN apt install -y build-essential cmake clang-format shellcheck curl
+
+COPY . /compile
+WORKDIR /compile
+
+RUN make configure
+RUN make compile
+
+FROM ubuntu
+COPY --from=compiler /compile/build/dist/bin/jsonschema /usr/local/bin/jsonschema
+WORKDIR /schema
+ENTRYPOINT ["/usr/local/bin/jsonschema"]

README.markdown

@@ -72,6 +72,22 @@ latest pre-built binaries, which you can run as follows:
 /bin/sh -c "$(curl -fsSL https://raw.githubusercontent.com/intelligence-ai/jsonschema/main/install -H "Cache-Control: no-cache, no-store, must-revalidate")"
 ```
 
+### From Dockerfile
+
+You can compile the software inside a container and run it with Docker:
+
+```sh
+docker build -t jsonschema .
+```
+
+Then you can validate files by mounting them in the `/schema` folder:
+
+```sh
+docker run -it -v "$PWD:/schema" jsonschema lint --verbose myschema.json
+# Optionally add to your .alias (or similar) file:
+# alias jsonschema="docker run -it -v \"$PWD:/schema\" jsonschema"
+```
+
 ### Building from source
 
 ```sh