PM2 fails to run the built `.pylon/index.js`

[ckhatton-pvfscaffolding]

Describe the bug
For one who wants to monitor with PM2 in a Docker image (or not with Docker), there seems to be a TypeError on executing pm2-runtime.

The app silently crashes with pm2 start as it's running inside a daemon.

The error occurs when running locally without using Docker. I can guess it's because of the old use of require(), but Pylon outputs a ESM file instead of CommonJS. Is there any way around this?

To Reproduce
Steps to reproduce the behaviour:

1. Create a default Pylon app.
2. Edit the last few lines of the Dockerfile to:

# Install PM2 as a project dependency (not global, due to user permissions)
RUN bun add pm2

# Run the app
USER bun
EXPOSE 3000/tcp
ENTRYPOINT [ "bun", "run", "pm2-runtime", "--interpreter", "bun", "/usr/src/pylon/.pylon/index.js" ]

Expected behavior
PM2 starts monitoring.

Additional context

• https://bun.sh/guides/ecosystem/pm2
• https://pm2.keymetrics.io/docs/usage/docker-pm2-nodejs

[ckhatton-pvfscaffolding]

I've just realised I didn't include the error itself 😅

pylon-app-1  | TypeError: require() async module "/usr/src/pylon/.pylon/index.js" is unsupported. use "await import()" instead.
pylon-app-1  |       at <anonymous> (/usr/src/pylon/node_modules/require-in-the-middle/index.js:101:39)
pylon-app-1  |       at <anonymous> (/usr/src/pylon/node_modules/pm2/lib/ProcessContainerForkBun.js:27:1)
pylon-app-1  | 2025-06-23T15:35:33: PM2 log: App [index:0] exited with code [1] via signal [SIGINT]                                                                                                              pylon-app-1  | 2025-06-23T15:35:33: PM2 log: App [index:0] starting in -fork mode-
pylon-app-1  | 2025-06-23T15:35:33: PM2 log: App [index:0] online
pylon-app-1  |  96 |     const isPatching = patching.has(filename)
pylon-app-1  |  97 |     if (isPatching === false) {
pylon-app-1  |  98 |       patching.add(filename)
pylon-app-1  |  99 |     }
pylon-app-1  | 100 |
pylon-app-1  | 101 |     const exports = self._origRequire.apply(this, arguments)

[schettn]

Hi @ckhatton-pvfscaffolding!

Should't pm2 support ESM? I definitely use it this way in pylon v3

pylon/packages/pylon-dev/src/index.ts

Line 162 in adc01bd

pm2.start(

The error occurs when running locally without using Docker.

So I assume you are running bun run pm2-runtime --interpreter bun /usr/src/pylon/.pylon/index.js locally?

[schettn]

Although bun run pm2-runtime --interpreter bun .pylon/index.js does not throw an error for me. The app does not start serving:

Instead bun run pm2-runtime "bun run .pylon/index.js" works for me:

[ckhatton-pvfscaffolding]

Thanks for looking into it. I believe it is specific to Docker. I tried that new command and I get No such file or directory. I have tried:

• ENTRYPOINT [ "bun", "run", "pm2-runtime", "\"bun run /usr/src/pylon/.pylon/index.js\"" ]
• ENTRYPOINT [ "bun", "run", "pm2-runtime", "\"bun run .pylon/index.js\"" ]

Here is my Dockerfile.

Dockerfile:

# Use the official Bun image
# See all versions at https://hub.docker.com/r/oven/bun/tags
FROM oven/bun:1 AS base

LABEL version="1.0.0"
LABEL description="Offical docker image for Pylon services (Bun)"
LABEL org.opencontainers.image.source="https://github.com/getcronit/pylon"
LABEL maintainer="office@cronit.io"

WORKDIR /usr/src/pylon

# Install dependencies into temp directory
# This will cache them and speed up future builds
FROM base AS install

RUN mkdir -p /temp/dev
COPY package.json bun.lock /temp/dev/
RUN cd /temp/dev && bun install --frozen-lockfile

RUN mkdir -p /temp/prod
COPY package.json bun.lock /temp/prod/
# Install with --production (exclude devDependencies)
RUN cd /temp/prod && bun install --frozen-lockfile --production

# Copy node_modules from temp directory
# Then copy all (non-ignored) project files into the image
FROM install AS prerelease
COPY --from=install /temp/dev/node_modules node_modules
COPY . .

# !! Run tests in the pipeline and not at build time

# Create .pylon folder (mkdir)
RUN mkdir -p .pylon
RUN bun run pylon build

# Copy production dependencies and source code into final image
FROM base AS release
COPY --from=install /temp/prod/node_modules node_modules
COPY --from=prerelease /usr/src/pylon/.pylon .pylon
COPY --from=prerelease /usr/src/pylon/package.json .
COPY --from=prerelease /usr/src/pylon/public public

# Install PM2 as a project dependency (not global, due to user permissions)
RUN bun add pm2

# Run the app
USER bun
EXPOSE 3000/tcp
# ENTRYPOINT [ "bun", "run", "/usr/src/pylon/.pylon/index.js" ]
# ENTRYPOINT [ "bun", "run", "pm2-runtime", "--interpreter", "bun", "/usr/src/pylon/.pylon/index.js" ]
# ENTRYPOINT [ "bun", "run", "pm2-runtime", "\"bun run /usr/src/pylon/.pylon/index.js\"" ]
ENTRYPOINT [ "bun", "run", "pm2-runtime", "\"bun run .pylon/index.js\"" ]

[ckhatton-pvfscaffolding]

Hey @schettn, any chance you could look further into this? 🙏 It would be nice to have PM2 monitoring with containerisation.

[schettn]

schettn@Mac bun-testing % bun run pm2-runtime "bun run .pylon/index.js"
(node:71360) [DEP0176] DeprecationWarning: fs.R_OK is deprecated, use fs.constants.R_OK instead
(Use `node --trace-deprecation ...` to show where the warning was created)
Started development server: http://localhost:3000
schettn@Mac bun-testing % bun run pm2-runtime "\"bun run .pylon/index.js\"" 
2025-10-01T10:29:01: PM2 log: Launching in no daemon mode
2025-10-01T10:29:01: PM2 error: (node:71570) [DEP0176] DeprecationWarning: fs.R_OK is deprecated, use fs.constants.R_OK instead
(Use `node --trace-deprecation ...` to show where the warning was created)
2025-10-01T10:29:01: PM2 log: App [index:0] starting in -fork mode-
2025-10-01T10:29:01: PM2 log: App [index:0] online
/bin/bash: bun run .pylon/index.js: No such file or directory

Have you tried removing the double quotes in you entry point?:

ENTRYPOINT [ "bun", "run", "pm2-runtime", "bun run .pylon/index.js" ]

instead of:

ENTRYPOINT [ "bun", "run", "pm2-runtime", "\"bun run .pylon/index.js\"" ]