---
project: env-file-hardening
type: project-plan
status: active
path: Tech/Projects
tags:
  - pbs
  - security
  - docker
  - ansible
  - secrets
created: 2026-04-19
updated: 2026-04-19
---

# Env File Hardening (Sidecar Pattern)

## Goal

Remove the easy path to PBS secrets. Right now `.env` files in
`/opt/docker` are readable by anyone with filesystem access — including
`pbsdeploy`. If the deploy key is compromised, an attacker can `cat .env`
and grab every API key and password instantly.

Goal: `pbsdeploy` can deploy containers without ever being able to read the
secrets they use.

## Threat Model

- **Primary risk:** `pbsdeploy` SSH key leaks → attacker SSHes in → reads
`.env` files → owns every service.
- **Mitigation goal:** eliminate the trivial read path. Raise the bar so an
attacker would need to escalate to root (no sudo on `pbsdeploy`), pivot
accounts, or break out of a container.
- **Accepted residual risk:** Determined attackers with deep access can
still cause damage. This is about removing low-hanging fruit, not achieving
zero risk.

## Architecture

**Sidecar injection pattern:**

- `.env` files stay owned by `root:root` with `600` perms.
- Ansible writes them via `become: yes` (sudo) — `pbsdeploy` never touches
the files directly.
- A tiny init container / sidecar runs as root, reads the locked `.env`,
and injects secrets into the main container as environment variables.
- Main containers read env vars exactly as they do today — **no application
code changes.**

## Design Decisions

- **Sidecar over Docker Compose secrets** — Compose secrets would require
refactoring every app (WordPress, n8n, pbs-hub, PBSII layers) to read from
`/run/secrets/` files instead of env vars. Sidecar gets the security win
with zero app-level changes.
- **Sidecar over external secret manager (Vault, etc.)** — overkill for
homelab/small prod scale. Revisit if we ever move to Kubernetes.
- **Ansible stays the deploy tool** — still writes `.env` files, just as
root with tight perms. `pbsdeploy` has no sudo entry, so it can't read them
back.
- **Scope: all services on production PBS** — WordPress, n8n, pbs-hub,
phpMyAdmin, everything in `/opt/docker`. No point hardening one service if
others still leak.
- **Staging first** — test on one service on staging, then roll out across
all services on staging, then move to production.

## How the Permissions Work

- Ansible SSHes in as `pbsdeploy` → uses `become: yes` to elevate for file
writes → files created as `root:root 600`.
- `pbsdeploy` can't `cat` them (no read perms). Can't `sudo cat` them
either (no sudoers entry).
- Docker daemon runs as root → sidecar container runs as root → can read
the files and inject into main container.
- Main container sees env vars, doesn't know or care where they came from.

## Next Steps

- [ ] Pick a non-critical service on staging to pilot the sidecar pattern
- [ ] Design the sidecar container (shell script? tiny Go/Python binary?
off-the-shelf image?)
- [ ] Update compose file for pilot service to include sidecar
- [ ] Update Ansible role to write `.env` as `root:root 600` (not
`deployer` group)
- [ ] Test on staging — verify containers still work, verify `pbsdeploy`
can't read files
- [ ] Roll out to all staging services
- [ ] Verify nothing broke in staging over a few deploys
- [ ] Roll out to production
- [ ] Remove `deployer` group's access to `.env` files (or the group
entirely, depending on what it ends up being used for)

## Open Questions

- What's the right sidecar implementation? Custom shell-based init
container vs. existing tool?
- Which pilot service to start with?
- Does anything else in `/opt/docker` currently rely on the `deployer`
group having read access that we'd break by tightening perms?

## Depends On / Related

- **SSH Login Alerting** — higher priority sibling project. Even before env
hardening is done, SSH alerts give us early warning if `pbsdeploy` is
compromised.
- **PBSII CI/CD** — same `pbsdeploy` / `deployer` setup on staging;
whatever we do here applies there too.


...sent from Jenny & Travis