Wrote out dockerfile cheat sheet

blog/src/SUMMARY.md

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-# Summary
+# SUMMARY
 
-- [Home](./home.md)
-- [Docker Talk](./dockertalk.md)
+# General
+
+- [Home](./general/home.md)
+
+# Docker
+
+- [Docker Talk](./docker/dockertalk.md)
+- [Dockerfile Cheat Sheet](./docker/dockerfile.md)
+- [Docker Compose Cheat Sheet](./docker/docker-compose.md)

blog/src/docker/docker-compose.md

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+# Dockerfile Cheat Sheet
+
+Coming soon...

blog/src/docker/dockerfile.md

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+# Dockerfile Cheat Sheet
+
+"Docker can build images automatically by reading the instructions from a `Dockerfile`. A `Dockerfile` is a text document that contains all the commands a user could call on the command line to assemble an image. This page describes the commands you can use in a `Dockerfile`." - Docker Docs
+
+This is meant to be a quick and dirty reference to help you get started. Reference the docker docs if you need more information, they're linked in the sources below.
+
+
+## Starting Point
+
+Arguments that dictate what to use as a starting point for the dockerfile
+
+### FROM
+
+Specifies what image to use as a base
+
+Usage:
+```
+FROM <image>
+FROM <image>:<tag>
+FROM <image>@<digest>
+```
+Notes:
+- **From is a required argument, and must come first**
+- If no tag is specified, the "latest" tag will be used
+
+
+## Metadata
+
+Arguments that don't affect how the image builds or container runs, but give information about the image
+
+### MAINTAINER (DEPRECATED)
+
+Allows you to specify an author - REPLACED with `LABEL Author="foo"`
+
+Usage:
+```
+LABEL Author="<name>"
+# MAINTAINER <name>
+```
+
+### LABEL
+
+Adds metadata to an image
+
+Usage:
+```
+LABEL "com.example.vendor"="ACME Incorporated"
+LABEL com.example.label-with-value="foo"
+LABEL version="1.0"
+LABEL description="This text illustrates \
+that label-values can span multiple lines."
+```
+
+## Setup
+
+### ENV
+
+Specifies environment variables
+Usage:
+```
+ENV <env_var_name> <value>
+```
+
+### ADD
+
+Copies files or directories to container's file system
+
+Usage:
+```
+# ADD <host_src> <container_dest>
+COPY <host_src> <container_dest>
+```
+Notes:
+- ADD can be buggy, use COPY where you can
+
+### COPY
+
+Copies files or directories to container's file system
+
+Usage:
+```
+COPY <host_src> <container_dest>
+```
+
+### VOLUME
+
+Create mount point, marks as holding external mounted items
+Usage:
+```
+VOLUME ["<DIR_PATH1>", "<DIR_PATH2>", ...]
+```
+
+
+### WORKDIR
+
+Set the current working directory
+
+Usage:
+```
+WORKDIR <DIR_PATH>
+```
+
+### SHELL
+
+Command to change the shell that RUN uses
+
+Usage:
+```
+SHELL ["<cmd>", "<arg1>", "<arg2>", ...]
+```
+Notes:
+- Only changes shell for following RUN commands, you can switch between shells if you so desire
+
+
+## Build
+
+### RUN
+
+Command to run in order to build the image
+
+Usage:
+```
+RUN <cmd>
+RUN ["<cmd>", "<arg1>", "<arg2>", ...]
+```
+
+Notes:
+- The build will fail if a run command returns a non-zero code
+- Runs with the "default shell" (can be changed with the SHELL command)
+
+
+
+
+### 
+
+## Running
+
+### EXPOSE
+
+A way of communicating/documenting which image ports should be forwarded when ran as a container
+
+```
+EXPOSE 80
+# ^ notes that tcp port 80 should be opened
+EXPOSE 53/udp
+# ^ Specifies udp on port 53
+EXPOSE 53/tcp
+EXPOSE 53/udp
+# ^ Specifies both udp and tcp
+```
+Notes:
+- Doesn't actually open the port, you'll need to add that to the docker-compose file or docker run (-p) command
+
+
+### CMD
+
+Marks the command to be run automatically when a container starts if none is manually marked at runtime
+
+Usage:
+```
+CMD ["<executable>", "<arg1>", "<arg2>"]
+CMD ["<arg1>", "<arg2>"]
+CMD <command> <arg1> <arg2>
+```
+Notes:
+- If you are also using ENTRYPOINT, you can use CMD to specify arguments only
+
+### ENTRYPOINT
+
+Marks the command to be run automatically when a container is run interactively, overrides CMD 
+Usage:
+```
+ENTRYPOINT ["<executable>", "<arg1>", "<arg2>"]
+ENTRYPOINT <command> <arg1> <arg2>
+```
+# Sources
+
+- [docs.docker.com](https://docs.docker.com/engine/reference/builder/)
+- [kapeli.com](https://kapeli.com/cheat_sheets/Dockerfile.docset/Contents/Resources/Documents/index)
+- [dockerlaps.collabnix.com](https://dockerlabs.collabnix.com/docker/cheatsheet/)
+