Buildpacks vs Dockerfiles for App Deployment

Buildpacks and Dockerfiles solve the same deployment problem from opposite directions.

A buildpack asks the platform to detect the application runtime and assemble a runnable image for you. A Dockerfile makes the build steps explicit and puts more responsibility in the repository.

For a small team, the decision is usually:

• choose buildpacks when the app fits a normal runtime and you want the simplest deploy loop;
• choose a Dockerfile when you need exact system packages, build stages, runtime flags, or container behavior;
• use an existing image when the image itself is already your release artifact.

Raff Apps currently supports automatic buildpacks, Dockerfile builds, existing container images, and Docker Compose imports. That means the team can choose the packaging model per service instead of committing the entire application stack to one build method.

What a buildpack does

A buildpack inspects the application and turns source code into a runnable image.

Typical detection inputs include files such as:

• package.json;
• Python dependency files;
• Go modules;
• PHP/Composer metadata.

The platform owns most of the image assembly.

A useful mental model is:

source code
→ detect runtime
→ install dependencies
→ build
→ create runnable image

The advantage is speed and simplicity. The trade-off is less control over the exact build environment.

What a Dockerfile does

A Dockerfile makes the image recipe explicit.

Example:

FROM node:22-alpine

WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev

COPY . .

ENV NODE_ENV=production
CMD ["node", "server.js"]

Now the repository owns:

• base image;
• system packages;
• dependency install;
• build steps;
• runtime command.

This improves control and portability, but it also means the team owns more of the container lifecycle.

Buildpacks are strongest for conventional applications

Buildpacks fit well when:

• runtime detection is straightforward;
• system dependencies are ordinary;
• one start command is enough;
• there is no unusual OS-level requirement;
• the team wants source-to-running-app with minimal configuration.

Examples:

• Next.js;
• Express;
• FastAPI;
• Django;
• Flask;
• Go HTTP apps;
• standard PHP applications.

Buildpacks are especially useful for small teams that do not want Docker maintenance to become part of every application release.

Dockerfiles are strongest when the runtime is unusual

Use a Dockerfile when the application needs:

• custom apt/apk packages;
• native libraries;
• image-processing tools;
• browser runtimes;
• multiple build stages;
• exact base-image control;
• custom filesystem layout;
• nonstandard startup behavior.

If the app requires ffmpeg, Chromium, GDAL, ImageMagick, a special libc variant, or another specific system dependency, a Dockerfile is often easier to reason about than trying to bend automatic detection around it.

Do not use Docker only for prestige

A Dockerfile is not automatically more production-ready than a buildpack.

A poor Dockerfile can introduce:

• unpinned base images;
• oversized images;
• unnecessary build tools in production;
• root execution;
• weak cache behavior;
• secret leakage during build;
• stale package layers.

Use Docker when the extra control solves a real requirement.

Build reproducibility matters in both models

Whether you use buildpacks or Dockerfiles, lock application dependencies.

Examples:

• package-lock.json;
• pnpm-lock.yaml;
• poetry.lock;
• pinned requirements.txt;
• go.sum;
• composer.lock.

A buildpack cannot make an unpinned dependency graph deterministic.

A Dockerfile cannot make latest reproducible.

Keep build-time and runtime configuration separate

Do not bake production secrets into the image.

Bad pattern:

ENV DATABASE_URL=postgres://...

Better model:

build artifact
+
runtime environment variables / secrets

This allows one artifact to move across environments without rebuilding just to change credentials.

Use Secrets Management for Cloud Apps for the generic secrets model.

Multi-stage Dockerfiles reduce image size

When Docker is required, multi-stage builds can separate compilation from runtime.

Example:

FROM node:22 AS build
WORKDIR /app
COPY . .
RUN npm ci && npm run build

FROM node:22-alpine
WORKDIR /app
COPY --from=build /app/dist ./dist
CMD ["node", "dist/server.js"]

The production image does not need to contain every build tool.

This can improve:

• image size;
• startup time;
• attack surface;
• dependency clarity.

Buildpacks do not eliminate runtime ownership

Even when the platform builds the image, the application team still owns:

• runtime version compatibility;
• dependencies;
• startup behavior;
• health endpoint;
• environment configuration;
• application security.

Automatic packaging is not automatic application correctness.

Health checks should not depend on build method

A buildpack-deployed app and Dockerfile-deployed app should expose the same health semantics.

The platform should be able to determine whether the new revision:

• started;
• bound to the expected port;
• can serve traffic;
• should receive traffic.

Packaging choice should not change the user's health-check expectations.

Persistent data should not live in the image layer

Both buildpack and Dockerfile images should be treated as replaceable.

Persistent data belongs in:

• managed databases;
• object storage;
• persistent volumes.

Do not rely on files written into the container/image filesystem surviving redeployment.

Raff Apps currently supports persistent volumes for stateful services.

Docker Compose is a separate packaging level

Raff Apps also supports Docker Compose import.

Compose is useful when the application already has several services such as:

services:
  web:
    build: ./web
  api:
    build: ./api
  worker:
    build: ./worker

Each service can still use its own Dockerfile or platform build behavior.

Compose describes the multi-service application topology; it does not replace decisions about how each service image is built.

Choose by operational cost, not only build time

A decision table:

Migration between the two should remain possible

A well-designed application should be able to move from buildpack to Dockerfile later.

That becomes easier when:

• dependencies are locked;
• environment variables are external;
• start command is clear;
• persistent state is external;
• health endpoint exists.

Avoid putting business logic into platform-specific build hooks.

Buildpack vs Dockerfile checklist

Choose buildpacks when:

• the runtime is standard;
• detection works;
• no unusual system dependency exists;
• simplicity matters.

Choose a Dockerfile when:

• build/runtime must be explicit;
• native/system packages matter;
• exact base image matters;
• multi-stage build is useful;
• portability of the image recipe matters.

In both cases:

• lock dependencies;
• keep secrets out of builds;
• externalize persistent state;
• define a health endpoint;
• keep rollback possible.

Frequently asked questions

Are buildpacks the same as Docker?

No. Buildpacks automatically turn source code into an OCI-compatible image. Dockerfiles explicitly define how the image is built.

Does Raff Apps require a Dockerfile?

No. Raff Apps currently supports automatic buildpacks, Dockerfiles, existing images, and Docker Compose imports.

When should I switch from a buildpack to a Dockerfile?

Switch when you need exact system packages, image construction, custom build stages, or runtime behavior that the buildpack cannot express cleanly.

Is a Dockerfile more portable?

Usually the build recipe is more explicit and portable across container platforms, but the application must still externalize state and configuration to remain portable.

Where should secrets go?

Keep secrets in runtime secret/environment configuration, not in the Dockerfile or built image.

Sources

• Raff Apps
• Cloud Native Buildpacks documentation
• Dockerfile reference