Docker

This guide assumes you have knowledge of the following topics:

• TypeScript
• Node.js
• Docker
• Virtualization

Why Docker?

Docker provides a consistent environment that ensures the correct operation of any bot in both development and production, as well as simplifying workflow by integrating with CI/CD tools.

With Docker, scaling a bot horizontally is simple, allowing workloads to be distributed across multiple instances as needed.

What files does a Seyfert project need?

There are four files we need:

• package.json: support for JavaScript modules
• seyfert.config.js: configurations for Seyfert
• /node_modules: dependencies
• /src or /dist: application entry point

Deploying with Node.js

Dockerfile for a TypeScript project

The example Dockerfile assumes the following about your project:

• It has the following npm scripts:
  • start: runs the application’s entry point
  • build: transpiles TypeScript code to JavaScript

Dockerfile

FROM node:<VERSION_TAG>

WORKDIR /project

COPY package*.json ./

# Ref: https://docs.npmjs.com/cli/v10/commands/npm-ci
RUN npm ci

COPY tsconfig.json ./
COPY seyfert.config.js ./
COPY /src ./src

# Ref: https://docs.npmjs.com/cli/v10/commands/npm-prune
RUN npm run build && \
    npm prune --production

ENV USER node
ENV NODE_ENV=production

# Restrict user permissions in production
USER $USER

CMD ["npm", "start"]

You must replace <VERSION_TAG> with the Node.js version you want to use.

With Multi-stage builds

While the previous image is functional, it’s not very optimal or secure. The following example uses multi-stage builds and dumb-init:

Dockerfile

# Base stage
FROM node:<VERSION_TAG>-alpine<ALPINE_VERSION> AS base

ENV DIR /project
WORKDIR $DIR

# Build stage
FROM base AS build

# Ref: https://github.com/Yelp/dumb-init
RUN apk update && apk add --no-cache dumb-init

COPY package*.json ./

RUN npm ci

COPY tsconfig.json ./
COPY seyfert.config.js ./
COPY /src ./src

RUN npm run build && \
    npm prune --production

# Production stage
FROM base AS production

COPY --from=build /usr/bin/dumb-init /usr/bin/dumb-init
COPY --from=build $DIR/node_modules $DIR/node_modules
COPY --from=build $DIR/dist $DIR/dist
COPY --from=build $DIR/package.json $DIR/package.json
COPY --from=build $DIR/seyfert.config.js $DIR/seyfert.config.js

ENV USER node
ENV NODE_ENV=production

USER $USER

CMD ["dumb-init", "node", "dist/index.js"]