Add Docker support

Author: Brandon Davis

.dockerignore

@@ -0,0 +1,24 @@
+# Markdown files
+*.md
+
+# Logs
+*.log
+
+# Python cache files
+*/__pycache__*
+
+# Virtual environment
+.venv
+
+# Git
+.git
+
+# GitHub templates
+.github
+
+# Utility scripts
+slacker.sh
+.travis.yml
+.vulture_whitelist.py
+LICENSE
+Makefile

Dockerfile

@@ -0,0 +1,9 @@
+FROM python:3.7.0-alpine3.8
+
+WORKDIR ['/app/slacker']
+
+COPY . .
+
+RUN pip install -r requirements.txt
+
+ENTRYPOINT ["python3", "slacker.py"]

Makefile

@@ -31,3 +31,7 @@ check-min-version:
 	.venv/bin/vermin -t 3.4 slacker slacker.py
 
 check: check-min-version check-cmds check-style static-analysis
+
+.PHONY: docker
+docker:
+	docker build -t slacker:local .

README.md

@@ -17,7 +17,7 @@ The first invocation of Slacker requires to setup a workspace using the `--init`
 Input workspace token: ****************************************************************************
 Added new workspace 'myworkspace' to config and made it active.
 You can now run slacker normally.
-myworkspace> 
+myworkspace>
 ```
 
 Slacker is ready for use afterwards with "myworkspace" as the active workspace. _Note that it is recommended to employ a user token, not a bot token!_
@@ -72,5 +72,14 @@ To setup a virtual development environment that doesn't pollute the general syst
 
 Run `make setup` to install required modules to ".venv" in the root of the repository, and issue `source .venv/bin/activate` to activate the environment. From here, the `python`, `python3`, `pip` etc. will map to ".venv" and the modules installed into it.
 
+# Docker
+A Dockerfile is provided to quickly get up an running with Slacker. To build the Docker image it is recommended to use the `docker` target in the Makefile `make docker`, which creates image `slacker:local`. Start the slacker container by executing `docker_run.sh`. By default the script will drop you into the REPL, but slacker commands can be given directly to the script.
+
+```
+% ./docker_run.sh -- files.list -c 10
+```
+
+> **Note:** slacker writes a configuration file to disk (`~/.slacker`). In order to keep the configuration file between subsequent runs the local volume mount in the container is required.
+
 # Contributing
 See [CONTRIBUTING.md](CONTRIBUTING.md).