Sidecar — Deploy-Time Pod Composition

Overview

Sidecars are additional containers that run alongside an application container in a shared Podman pod. They share the network namespace (localhost connectivity) while maintaining separate filesystems. Sidecar templates are embedded in the charly binary — any image can get any sidecar at deploy time without image rebuilds.

Quick Reference

Action	Command
List available sidecars	`charly config --list-sidecars`
Attach sidecar	`charly config <image> --sidecar tailscale`
Attach with env	`charly config <image> --sidecar tailscale -e TS_HOSTNAME=my-app`
Check sidecar status	`charly cmd <image> --sidecar tailscale "tailscale status"`

Architecture

Sidecar templates are compiled into the charly binary via go:embed — they are name-first sidecar-kind nodes in the embedded default charly/charly.yml (plain node-form YAML), parsed through the SAME unified loader as any project charly.yml (folded into UnifiedFile.Sidecar). A project may also declare its own sidecar-kind nodes that extend/override the embedded set. At deploy time, charly config --sidecar <name> merges the embedded template with the project's templates and the per-machine overrides from charly.yml, then generates quadlet files.