signalman

Small application that exposes a HTTP endpoint which can be used to send (UNIX) signals to a child process.

Wrapping the main container's application with signalman allows sidecar containers to control behavior using HTTP requests.

E.g. very usefull when doing lift-and-shift of legacy applications into Kubernetes and the application supports reloading configurations when receiving a SIGHUP signal.

Security disclaimer

The exposed HTTP API is not served with TLS nor does it require any form of authentication.

Getting signalman

Download the latest binary from the release page or build it yourself (see Building signalman)

Usage

Simply start signalman with the command (and args) that should be wrapped:

$ signalman <command> [<args> ...]

Examples:

$ signalman /some/app arg1 arg2

$ signalman sleep 60

HTTP API

Method	Path	Description
`GET`	`/status`	Return status with version info
`POST`	`/term`	Sends signal `TERM` to wrapped process. If the process doesn't terminate within `SIGNALMAN_TERM_TIMEOUT` seconds a `KILL` is sent
`POST`	`/kill`	Sends signal `KILL` to the wrapped process
`POST`	`/signal/<num>`	Sends signal `<num>` to the wrapped process

Example:

$ curl -X POST http://localhost:30000/term

Configuration

signalman supports a few configuration options using environment variables:

Name	Description	Default (if not set)
`SIGNALMAN_LISTEN_ADDRESS`	Address and port signalman will listen for HTTP requests on	`localhost:30000`
`SIGNALMAN_TERM_TIMEOUT`	Duration in seconds to wait for process to response to TERM signal	`10`
`SIGNALMAN_LOG_LEVEL`	Log level (debug/info/warn/error/dpanic/panic/fatal)	`info`
`SIGNALMAN_LOG_CONFIGFILE`	Path to file containing ⚡ uber-go/zap logger config. See `testdata/example-log-config.json` for example

Building signalman

signalman can be built using make

$ make build

.. or cross-built:

$ make PLATFORM=linux ARCH=arm GOARM=6 xbuild