Update the docker image to remove the `run.sh` script and instead run the
exporter directly. This keeps the docker image as simple as possible.
Update README file with extra info on how to collect textfile metrics in
a docker container.
BREAKING CHANGE: Using the textfile collector in docker now requires setting environment variables.
Update the project Dockerfile to compile the tool during the docker build
instead of assuming the goreleaser tool was run previously. This allows
for custom data to be set in the compiled tool (e.g. compiled by docker)
and removes the dependency on another build step.
Update the Makefile to include a new command to build the tool for docker
which sets the version data correctly. Rename the docker commands to follow
the `docker/build-...` format to avoid confusion with the build commands.
Add a project Dockerfile to allow deploying the application in a docker
container. Add a `run.sh` script to start the application in the container.
Add Makefile commands to build the docker image based on the Dockerfile.
Fix possible nil reference error in the `db` package.