🐳 Dockerizing My Go CLI App with SQLite Support

📦 About mycli

mycli is a lightweight command-line app built with Cobra in Go. It allows you to:

• Add, list, or search records

• Use SQLite as a local DB (via gorm)

• Run everything inside Docker — no need for Go or SQLite installed on your system

⚙️ Dockerfile

FROM golang:alpine

RUN apk add --no-cache gcc musl-dev sqlite-dev

WORKDIR /app

COPY go.mod go.sum ./
RUN go mod download

COPY . .

ENV CGO_ENABLED=1

RUN go build -o imdb .

CMD ["./imdb"]

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#FROM golang:alpine

• Use the official Go compiler based on the Alpine Linux distro

• Why: Small, fast, and perfect for lightweight CLI builds

• Internally: Docker pulls a tiny Linux image with Go pre-installed

#RUN apk add --no-cache gcc musl-dev sqlite-dev

• Install system packages needed for SQLite + CGO builds

• Why:

  • gcc is needed to compile C code via CGO

  • musl-dev provides C stdlib headers used by Go

  • sqlite-dev gives C headers + libs for SQLite
    🔧 Internally: Adds these packages into the image during the build stage
    🚫 --no-cache avoids caching indexes to keep the image small

#WORKDIR /app

• Set working directory inside the container

• Why: So future COPY, RUN, and CMD all run from /app

• Internally: Docker will cd /app before executing next instructions

• Files copied with COPY . . will now go into /app

#COPY go.mod go.sum ./

• Copy module files first to leverage Docker caching

• Why: Keeps go mod download cached unless dependencies change

• Internally: Docker copies these files into /app

• Speeds up builds by avoiding redundant downloads

#RUN go mod download

• Download Go dependencies (from go.mod)

• Why: Prepares all packages so the final build works offline

• Internally: Runs go mod download in /app inside the build layer

• Caches module dependencies (e.g., gorm, cobra)

#COPY . .

• Copy all remaining project files (main.go, commands, etc)

• Why: Add actual source code to be compiled

• Internally: Everything in your project root is copied into /app

#ENV CGO_ENABLED=1

• Enable CGO (Go to C interop)

• Why: Needed to use C-based SQLite library (sqlite3)

• Internally: Go uses this env var during go build to allow C linking

• Without this, build will fail with undefined: _sqlite3_open

#RUN go build -o imdb .

• Build your Go CLI binary

• Why: Compiles Go code into imdb binary at /app/imdb

• Internally: Runs the go build command inside container

• Target output: /app/imdb

#CMD ["./imdb"]

• Set the default command to run when the container starts

• Why: Makes it behave like a CLI — can pass list, search etc.

• Internally: Docker executes /app/imdb by default

• You can override it by: docker run imdb list → becomes ./imdb list

---

INTERNAL WORKING

RUN go build -o imdb .

CMD ["./imdb"]

Running: docker run main list

Docker internally runs: ./imdb list

---

⚙️ Docker Compose

version: "3.8"

services:
  imdb:
    build: .
    container_name: imdb-cli
    volumes:
      - ./data:/app/data
    entrypoint: ./imdb

# Breakdown

• build: . → Builds from the current Dockerfile

• container_name → Names the container imdb-cli

• volumes → Mounts ./data folder to /app/data to persist SQLite DB

• entrypoint → Runs ./imdb as the CLI binary inside the container

💾 What Does volumes Do?

volumes:
  - ./data:/app/data

• ./data → Local folder (host)

• /app/data → Inside container
  ✅ This keeps your SQLite DB persistent even after stopping the container.

• ✅ Why: Persists your SQLite database even after the container stops

• 📂 Your DB file (e.g. todos.db) will stay saved in ./data

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🧪 Usage

Running :-

docker-compose run imdb list
docker-compose run imdb search Inception

Docker internally runs:-

./imdb list
./imdb search Inception

#inside the Docker container, with persistent data saved to ./data.

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🚀 Run Your CLI with Docker Compose

# Build the image and run the container interactively
docker-compose run imdb

# Run a specific command (e.g. list movies)
docker-compose run imdb list

# Run with arguments (e.g. search a movie)
docker-compose run imdb search Inception

# Clean up (stop and remove containers)
docker-compose down

Thanks for reading! If you found this helpful or have suggestions, feel free to connect or drop a comment.