| title | date | slug |
|---|---|---|
Docker Commands Reference |
2019-10-08 |
docker-reference |
| Command | Description |
|---|---|
| start | Start Container |
| stop | Stops Container |
| restart | Restart Container |
| kill | Kill Container |
| attach | Attach terminal to running container |
| exec | Excutes command within a running container |
| inspect | Detail output about running container in JSON |
| history | Shows history of container image |
Dockerfile Commands
| Command | Reference |
|---|---|
| FROM | Base image, usually first |
| WORKDIR | Set's working directory |
| ADD | Adds file from source to destination. Can be URL, Will Unzip |
| COPY | Copy from host machine. Best practice to use unless you need ADD's functionality. |
| EXPOSE | Expose a port from container at runtime |
| VOLUME | Creates a mount point for container |
| RUN | Executes command in a new layer and commits to image. Can have many. |
| CMD | Provides default behavior for launching an instance. Only one per image and not hole image is being built. |
| ENV | Sets and environment variable that is available through build and during container run. |
| ARG | Variables that can be passes into the build command. Don't use for sensitive info. |
| LABEL | Key-Value parr's exposed as image metadata |
Dockerfile Best Practices
- Keep image small
- As few layers as possible
- Avoid breaking cache
- Avoid known vulnerabilities
Keeping Image Small
- Use small or slim base image
- Combine layers
- Use .dockerignore
- Use multistage build
- Best for compiled code or have lot of intermediate steps
- Keep final stage as small as possible
- All other stages are discarded
- Change user to non-root user
- Better security
- Adds additional layer
HEALTHCHECK command
- Tells Docker how to check status of container
- HEALTHCHECK --interval=30s CMD curl -f http://localhost/status || exit 1
Compose File Syntax
- Image
- Build
- Image and Build