no templates
Works on plain text. No build system, no runtime hooks, no dependencies.
devsyringe
cli / static files / regex injection
Inject dynamic values into static files without manual copy-paste.
Devsyringe is a Go CLI that runs a command, extracts a value with a regex, and injects it into one or more files. You define the rules once in `devsyringe.yaml`, then run one command.
Install:
go install github.com/alchemmist/devsyringe/cmd/dsy@latest
$ dsy inject -c devsyringe.yaml → Update ./.env. → Update ./static/config.js. status: ok mode: strict
Why
Static files do not have runtime config injection. When your tunnel URL, token, or build value changes, you end up copying it into HTML, JS configs, or legacy files. Devsyringe automates the update without turning your project into a templating system.
The core idea is simple: run a command, extract the value with a regex, and inject it into one or more target files using clues.
one source, many files
Extract once with a regex, inject into any number of targets.
local and CI
Run `dsy inject` locally, or in CI to keep docs and configs up to date.
observable
Built-in TUI shows running processes, status, and logs.
Flow
Define sources and targets in YAML, then run one command.
1. run
Start a command and read its live output.
2. match
Use `mask` (regex) to capture the dynamic value.
3. locate
Find target lines by `clues` — multiple words on the same line.
4. inject
Replace the matched value and write back to disk.
Tip: run dsy without arguments to open the TUI process
table.
Use Cases
Designed for situations where simple files still need dynamic values.
tunnel URLs
Extract a live URL from a tunnel command and inject it into `.env` and client configs.
tokens and keys
Pull tokens from CLIs and keep infra configs in sync.
build metadata
Inject git SHA or build versions into docs and status pages.
docs automation
Update README or LaTeX files with live stats pulled from APIs.
infra updates
Fetch addresses, endpoints, or secrets and update static config files.
Demo
A single command starts a tunnel, grabs the URL, and updates multiple files in place.
Install
Choose the package manager you already use.
# Go go install github.com/alchemmist/devsyringe/cmd/dsy@latest # Arch (AUR) paru -S devsyringe # or: yay -S devsyringe # macOS (brew) brew tap alchemmist/homebrew-tap brew install devsyringe
CLI
Core commands that power the workflow.
inject
Start an injection based on a YAML config.
list
Show the dynamic list of running processes.
logs
Read logs for a running process by title.
stop / delete
Stop a process or delete it with logs.
Run dsy help or dsy [command] --help for
options.
flow map
mode: strict
latency: depends on source
source command
lt --port 8080
live output stream
→
mask (regex)
https://...loca.lt
first match wins
→
targets + clues
.env and src/config.js
replace only matched lines
source: command output
match: regex
targets: clues
file update
Each `serum` describes one dynamic value: how to obtain it, how to match it, and where to inject it.
serums:
localtunnel:
source: lt --port 8080
mask: https://[a-z0-9\\-]+\\.loca\\.lt
targets:
env_file:
path: ./.env
clues: ["API_BASE_URL"]
frontend_config:
path: ./src/config.js
clues: ["API_URL", "const"]
What it does: starts `lt`, waits for a tunnel URL in the output, then replaces the value on lines that contain the clues in both `.env` and `src/config.js`.
Run: dsy inject -c devsyringe.yaml.
Step by step:
1. command
Launches `lt --port 8080` and reads the stream output.
2. match
Captures the first URL matching the regex mask.
3. replace
Finds lines that include the clues and replaces the matched value.
4. write
Saves both files and prints update logs to the terminal.