How to cache bunx folder ?

[seepine]

I found the BUN_INSTALL_CACHE_DIR env, but it doesn't seem to be effective for Bunx.

Dockerfile

FROM oven/bun:alpine
RUN apk add --no-cache libstdc++

WORKDIR /workspace
ENV WORKSPACE_FOLDER=/workspace
EXPOSE 3000
ENTRYPOINT ["/bin/sh", "-c", "BUN_INSTALL_CACHE_DIR=$WORKSPACE_FOLDER/.bun/install/cache && bunx xxx"]

And

docker run --rm -v ./data:/workspace bun-demo

But i cannot found .bun dir in my ./data

[SX110903]

el problema es que BUN_INSTALL_CACHE_DIR solo afecta al cache de paquetes instalados, no al de bunx que va por otro lado. para cachear bunx en docker tienes que montar el directorio ~/.bun directamente:

FROM oven/bun:alpine
WORKDIR /workspace
VOLUME /root/.bun
ENTRYPOINT ["bunx", "xxx"]

y luego en el docker run:

docker run --rm -v bun-cache:/root/.bun tu-imagen

con un named volume se mantiene entre ejecuciones. si estas en ci/cd la mayoria tienen soporte para cachear volumes de docker directamente. la ruta exacta del cache de bunx suele ser ~/.bun/install/cache pero el volumen entero es lo mas facil de gestionar

[Shubrathshetty]

Your ENV is set only inside the ENTRYPOINT command:
ENTRYPOINT ["/bin/sh", "-c", "BUN_INSTALL_CACHE_DIR=$WORKSPACE_FOLDER/.bun/install/cache && bunx xxx"]
This sets the var too late / only for that line — sometimes bunx ignores it or doesn't create dirs if no download happens.
Fix (short version)
Move the env var to Dockerfile level + pre-create the dir:
FROM oven/bun:alpine
RUN apk add --no-cache libstdc++

WORKDIR /workspace
ENV WORKSPACE_FOLDER=/workspace
ENV BUN_INSTALL_CACHE_DIR=/workspace/.bun/install/cache

Pre-create so permissions are good (runs as root)

RUN mkdir -p $BUN_INSTALL_CACHE_DIR

EXPOSE 3000
ENTRYPOINT ["bunx", "xxx"] # or keep shell if needed
Now, when bunx xxx downloads anything:
Cache goes to /workspace/.bun/install/cache
After docker run -v ./data:/workspace ..., you'll see ./data/.bun/install/cache populated.
If xxx is a one-off tool that doesn't download (or already cached in image), nothing new appears. Test with something like bunx cowsay hello to force a download.

[MukundaKatta]

Two things going wrong at once — both point at how Docker layering interacts with bunx caching.

Why your BUN_INSTALL_CACHE_DIR setup silently does nothing

ENTRYPOINT ["/bin/sh", "-c", "BUN_INSTALL_CACHE_DIR=$WORKSPACE_FOLDER/.bun/install/cache && bunx xxx"]

There are three problems stacked here:

1. The && makes the assignment temporary and not exported. Writing X=Y && bunx … assigns X in the shell and then runs bunx as a child process that does not inherit X. You want either X=Y bunx … (single command line, X is exported just for that child) or export X=Y; bunx ….
2. $WORKSPACE_FOLDER is expanded at container-start time, not at build time. That's fine, but combined with (1) it's just dead text.
3. bunx only writes to the install cache for packages it actually had to download. If the package is already in $HOME/.bun/install/cache (the default), nothing is written to your override. On a fresh container the first bunx download will populate the cache — so if you're testing with docker run --rm, you're seeing a cold cache every run.

Actually persisting bunx packages across runs

Two approaches, pick per taste:

A. Bake the packages into the image (best for CI / production).

FROM oven/bun:alpine
RUN apk add --no-cache libstdc++
WORKDIR /workspace

# Pre-warm the cache at build time — baked into the image layer.
RUN bunx --help >/dev/null && \
    bunx --bun <your-tool>@<version> --version || true

ENTRYPOINT ["bunx", "<your-tool>"]

The install cache lives at /root/.bun/install/cache (the default), so anything bunx downloads during RUN is committed to the image. Pin the version — bunx foo@latest would defeat the caching.

B. Mount a host volume at /root/.bun (best for dev loops).

FROM oven/bun:alpine
RUN apk add --no-cache libstdc++
WORKDIR /workspace
ENTRYPOINT ["bunx", "xxx"]

docker run --rm -v bun_cache:/root/.bun -v ./data:/workspace bun-demo

Note the volume is on /root/.bun, not ./data/.bun. Bun resolves the install cache from $HOME unless you set BUN_INSTALL_CACHE_DIR in the process environment that bun sees — so either mount the whole /root/.bun, or:

ENV BUN_INSTALL_CACHE_DIR=/workspace/.bun/install/cache
ENTRYPOINT ["bunx", "xxx"]

…and then -v ./data:/workspace will persist the cache to ./data/.bun/install/cache as you originally wanted. The critical change is ENV (Docker image-level environment) instead of a shell-local assignment, so the variable is in bunx's process env by the time it runs.

Quick sanity check

docker run --rm -v ./data:/workspace bun-demo sh -c 'env | grep BUN; bunx --version'

If you don't see BUN_INSTALL_CACHE_DIR=... in the output, the variable isn't actually set — which was the original issue.

[seepine]

Maybe

FROM oven/bun:alpine
RUN apk add --no-cache libstdc++

WORKDIR /workspace
ENV WORKSPACE_FOLDER=/workspace
ENV BUN_INSTALL_CACHE_DIR=/workspace
EXPOSE 3000
ENTRYPOINT ["/bin/sh", "-c", "bunx xxx"]

But the way, BUN_INSTALL_BIN need to add to PATH

ENV BUN_INSTALL_BIN="~/.bun/bin"
ENV PATH="$BUN_INSTALL_BIN:~/.local/bin:$PATH"