Simplenetes Pod Compiler (podc)

podc takes a Simplenetes Pod YAML specification and turns it into a runnable standalone shell script.

The compiled shell script is a POSIX compliant shell script which manages the full pod life cycle. It uses podman (instead of Docker) to create and manage pods and containers in a root-less environment.

A Simplenetes pod is similar to a Kubernetes pod but is simpler. Simplenetes pods can be used on their own or within a Simplenetes cluster.

podc is written in Bash.

Features

podc features:

- Standalone shell script to manage the full pod cycle
- Uses podman for running root-less containers
- Separates stdout and stderr logging, per container
- Compile in dev mode to mount local directory while developing for quick iterations
- Support for ramdisks to never put sensitive files on disk
- Support for non interruptive config updates of processes running (say for updating haproxy.conf)
- Step into a shell into any container in the pod
- Signal some or all containers
- Startup probes
- Readiness probes
- Liveness probes
- Mount shared and private volumes
- Small and easily understandable specification
- Ingress configs if running in a Simplenetes cluster

Examples

See https://github.com/simplenetes-io/podc/tree/master/examples for more examples.

Quick example:

cd examples/nginx
podc
./pod run
./pod ps
curl 127.0.0.1:8080
./pod logs
./pod rm

How does this work?

The podc program (a bash script) parses the pod.yaml file and outputs a runnable shell script, which is the pod.

The yaml file can contain variables such as ${portHttp}, which can be defined in the pod.env file and are then substituted in. Variables which are not in the .env file are read from environment.

The resulting pod file is embedded with shell script code to leverage podman to manage the full pod life cycle.

podc and it's yaml processor are both written in Bash, the resulting output is however in POSIX shell, so you can run the pod using dash, ash, busybox ash, etc, no bash needed.

Note: When podc is used by Simplenetes in a cluster project it does it's own preprocessing and varibles are then not read from the pod's .env file nor from the environment but from the cluster-vars.env file only.

But why?

podc and the Simplenetes cluster manager are both a reaction to the too much magic that Kubernetes packs.

podc was compiled using space.sh, which is your friend to make shell script applications.

Install

podc is a standalone executable, written in Bash and will run anywhere Bash is installed.

Dependencies are:
Optional dependecies used by the podman runtime to check if ports are busy prior to creating the pod:

• sockstat, netstat or lsof.

netstat is commonly contained in the net-tools package and can be installed on Debian-based distributions as:

sudo apt-get install -yq net-tools

The reason podc is written in Bash and not POSIX shell is that it has a built in YAML parser which requires the more feature rich Bash to run. Even though podc it self is a standalone executable it requires a runtime template file for generating pod scripts. This file must also be accessible on the system.
podc will look for the podman-runtime template file first in the same directory as it self (./), then in ./release and finally in /opt/podc.
The reason for that it looks in ./release is because it makes developing the pod compiler easier.

Check out the latest release here or manually download it from the command line:

LATEST_VERSION=$(curl -s -H "Accept: application/vnd.github.v3+json" https://api.github.com/repos/simplenetes-io/podc/releases/latest | grep tag_name | cut -d":" -f2 | tr -d ",|\"| ")
curl -LO https://github.com/simplenetes-io/podc/releases/download/$LATEST_VERSION/podc
curl -LO https://github.com/simplenetes-io/podc/releases/download/$LATEST_VERSION/podc-podman-runtime
chmod +x podc
sudo mv podc /usr/local/bin
sudo mv podc-podman-runtime /usr/local/bin

Set up ssh-enabled VM for running

podc is for Linux only, run a VM if on any other OS.

./boot2podman_download_create_and_run.sh