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Docker

Docker Process

Docker Process (from https://www.youtube.com/watch?v=oGPjzCBZGzg)

Good videos to understand docker: Monis Yousuf

Dockerfile​

A YAML (.yml) file for building a Docker Image. It can installs dependencies, copy your code, expose ports, and run the app

A sample dockerfile

version: "3.9" # Docker Compose file format version

services:
  ollama: # "ollama" LLM Backend API Server
    image: ollama/ollama  # Official Ollama image
    container_name: ollama
    ports:
      - "11400:11434"  # Ollama API port; Map port 11400 of the host to port 11434 of the container
    volumes:
      - ollama_data:/root/.ollama # Persistent storage for downloaded models
	  			  # '/root/.ollama' is the model storage location inside the container.
    restart: unless-stopped # Automatically restart the container unless it is explicitly stopped by the user.
    			    # This is useful for ensuring Ollama is always running after reboots or crashes.

  openwebui: # "openwebui" Web-based Frontend for LLM
    image: ghcr.io/open-webui/open-webui:main  # Official OpenWebUI image
    container_name: openwebui
    ports:
      - "3000:8080"  # Host port 3000 maps to OpenWebUI's internal port 8080
    environment:
      - OLLAMA_API_BASE_URL=http://ollama:11434  # Connect OpenWebUI to Ollama backend
    depends_on:
      - ollama  # Ensure Ollama starts before OpenWebUI
    restart: unless-stopped

volumes:
  ollama_data:  # Persistent volume for Ollama models

Docker Image​

A read-only blueprint for making Docker Container. Think of it as a food recipe

List all docker images​

docker images

Sample Output:

REPOSITORY                      TAG       IMAGE ID       CREATED         SIZE
ghcr.io/open-webui/open-webui   main      21bb7e0892cf   2 weeks ago     4.78GB
ollama/ollama                   latest    2b23bc85a2d2   5 weeks ago     2.27GB

Docker image hardware usage​

docker stats

Sample Output:

CONTAINER ID   NAME         CPU %    MEM USAGE / LIMIT       MEM %   NET I/O           BLOCK I/O      PIDS
21bb7e0892cf   open-webui   0.12%    12.34MiB  /  1.953GiB   0.62%   1.23kB / 4.56kB   7.89MB / 0B    5

Remove a docker image​

sudo docker rmi -f <image_id>

Example: ```bash sudo docker rmi -f ffc5b597096e


* If an image is not removable due to some errors like
	
> Error response from daemon: conflict: unable to delete image_id (cannot be forced) - image has dependent child images

Then use the image name with tag in the format `image_name:tag`

> Always check what the error is saying and see if it is conveying something important.

Example: `sudo docker rmi -f anaconda/conda:cpu`

<br />

### Recreate new image after making changes to exisitng image

Let's say you have a container 'bd91ca3ca3c8' running, and you want to create a new image after you made changes in the container. Generating another image will allow you to preserve your changes.

In that case you can run:

```bash
docker commit -p -a "author_here" -m "your_message" bd91ca3ca3c8 name_of_new_image

Example: docker commit -p -a "Ajay" -m "edit in frontend" bd91ca3ca3c8 OWUI_new

  • -p pauses the container while commit command is building the new image.

  • -a supply author information of the new image.

  • -m add a comment just as in the Git.


Zipping docker image​

docker save -o <tar_filename.tar> <image_name:tag>

Example docker save -o ollama.tar ollama/ollama:latest


Load an image from Zipped file​

docker load -i <name_of_archive_file_with_extension>

Example docker load -i ollama.tar


Docker Image Prune​

Before docker prune, docker images output:

ajay@ajay:~$ docker images
REPOSITORY                      TAG                  IMAGE ID       CREATED         SIZE
<none>                          <none>               a395134a60ee   3 hours ago     461MB
<none>                          <none>               718fe7aef004   3 hours ago     461MB
<none>                          <none>               c2f8543ff7d0   3 hours ago     461MB
python                          3.11.13-slim         2ba2e944f9cd   2 weeks ago     125MB
pipeline                        latest               823b5c57ed73   3 weeks ago     4.01GB
ghcr.io/open-webui/open-webui   main                 ca42d907c22d   3 weeks ago     4.78GB
python                          3.11-slim-bookworm   f3bfd8e9386c   2 months ago    130MB
ubuntu                          latest               a04dc4851cbc   7 months ago    78.1MB
docker image prune -f
ajay@ajay:~$ docker image prune -f 
Deleted Images:
deleted: sha256:718fe7aef004f33ca8a89507370bdee3a1c37323a1562fbb0f80e57b23b5e93d
deleted: sha256:d9db36184582b1f257a4e3b73be9d3db7fa29efb022c767527dd3ed895d9250c

After docker prune, docker images output:

Total reclaimed space: 1.009GB
ajay@ajay:~$ docker images
REPOSITORY                      TAG                  IMAGE ID       CREATED         SIZE
python                          3.11.13-slim         2ba2e944f9cd   2 weeks ago     125MB
pipeline                        latest               823b5c57ed73   3 weeks ago     4.01GB
ghcr.io/open-webui/open-webui   main                 ca42d907c22d   3 weeks ago     4.78GB
python                          3.11-slim-bookworm   f3bfd8e9386c   2 months ago    130MB
ubuntu                          latest               a04dc4851cbc   7 months ago    78.1MB

Docker Container​

A running instance of an image. Think of it is a food made using a recipe

List all docker containers (with their status)​

docker ps -a

Sample Output:

CONTAINER ID   IMAGE                                COMMAND           CREATED       STATUS                 PORTS                                         NAMES
a839cf0e8ee9   ghcr.io/open-webui/open-webui:main   "bash start.sh"   3 hours ago   Up 3 hours (healthy)   0.0.0.0:3000->8080/tcp, [::]:3000->8080/tcp   open-webui

Enter into the shell of a docker container​

sudo docker exec -it <container_id> /bin/bash

Example: ```bash sudo docker exec -it ffc5b597096e /bin/bash


Note: There won't be any packages (like nano, vim) installed inside the shell of a docker container

<br />

### Remove a docker container

```bash
docker rm -f <container_id>

Example: ```bash sudo rmi -f c22e695dfda2


<br />

### Display container logs

```bash
docker logs -f $(docker ps -q -f name=<container_name>)

OR

docker logs <container_name>

Example: docker logs -f $(docker ps -q -f name=open-webui) or docker logs open-webui


Docker Container Prune​

Delete all Exited & Created Containers

Before docker prune, docker ps -a output:

CONTAINER ID   IMAGE                                COMMAND                  CREATED       STATUS                  PORTS                                                                                          NAMES
c32f661bce29   file:latest                          "/bin/sh -c 'uvicorn…"   6 days ago    Exited (1) 6 days ago   
docker container prune -f

After docker prune, docker ps -a output:

CONTAINER ID   IMAGE                                COMMAND                  CREATED       STATUS                  PORTS                                                                                          NAMES
c32f661bce29   file:latest                          "/bin/sh -c 'uvicorn…"   6 days ago    Exited (1) 6 days ago

Docker Compose​

A tool for defining and running multi-container Docker applications using a YAML file (usually docker-compose.yml, not strict, it can be ajay-compose.yml or any name [see this])

Think like you have a dockerfile like the one above; If you make two separate dockerfiles for the Ollama and Open WebUI, you need to maintain them separately. But with docker compose, you can define them in a single file and run with a single command like docker compose up

--build option in docker compose​

A command like docker compose up --build will rebuild new images whenever you run this command. Without the --build, the docker will reuse the old image, where your new changes are not reflected.