# Cloud Native Buildpacks on Podman

#### What is Cloud Native Buildpacks?

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#### What is Podman?

To quote from the official documentation:

> Podman is a daemonless, open source, Linux native tool designed to make it easy to find, run, build, share and deploy applications using Open Containers Initiative (OCI) Containers and Container Images.

It can be used as a standalone daemonless CLI with sub-commands and flags almost identical the standard `docker` CLI. You can even alias `docker=podman` and everything should work as expected.

Beside running as a standalone daemonles CLI `podman` can also serve as a `docker` API daemon using `pomdan system service` sub-command. You just need to set the `DOCKER_HOST` environment and most applications will pick it up (`pack` is one of them).

While `podman` is native to Linux you still can enjoy it on `macOS` using virtual machine. There is sub-command `podman machine` facilitating VM creation making it really easy.

## Setup

You will need:
* `podman v3.3.0` or newer
* `pack v0.22.0` or newer

### macOS

#### Installation

brew install podman

#### Virtual Machine

##### 1. Init


podman machine init --cpus=2 --disk-size=30 --memory=8192

Where:

- `--cpus` is the number of CPUs we'll allocate to the VM.
- `--disk-size` is the amount of disk space we'll give the VM. (GBs)
- `--memory` is the amount of memory we'll allocate to the VM. (MBs)

##### 2. Start


podman machine start

#### Connection


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1. Add the SSH key for the podman VM to your keychain:

    ssh-add -k "$HOME/.ssh/podman-machine-default"

2. Configure `DOCKER_HOST` with the connection information:

    export DOCKER_HOST="$(podman system connection ls --format="{{.URI}}" | grep root)"

**Tip**: put the commands into your shell init file (e.g `~/.zshrc`).

### Fedora

#### Installation

sudo dnf -y install podman

For installation on other distributions check out [offical documentation](https://podman.io/getting-started/installation#linux-distributions).

#### Service

Expose the service using `systemd`:

systemctl enable --user podman.socket
systemctl start --user podman.socket

#### Connection

export DOCKER_HOST="unix://$(podman info -f "{{.Host.RemoteSocket.Path}}")"

**Tip**: put the command into your shell init file (e.g `~/.bashrc`).

# Usage

## Build

### Source


git clone https://github.com/buildpacks/samples

### `pack build`


pack build sample-app -p samples/apps/ruby-bundler/ -B cnbs/sample-builder:bionic

Where:
- `sample-app` is the image name of the image to be created.
- `-p` is the **path** to the application source.
- `-B` is the **[builder][builder]** to use.

### Results


podman images

[builder]: https://buildpacks.io/docs/concepts/components/builder/

# Known Issues & Limitations
* On `macOS` bind mounts do not work since the VM cannot access host file system.
* With more time consuming builds and `--trust-builder=true` following error may occur:

  ERROR: failed to image: error during connect: Get "http://%2Fvar%2Frun%2Fdocker.sock/v1.40/info": EOF

There is a workaround for this, increase timeout of podman service:

  cat <<EOF > /etc/systemd/user/podman.service
  [Unit]
  Description=Podman API Service
  Requires=podman.socket
  After=podman.socket
  Documentation=man:podman-system-service(1)
  StartLimitIntervalSec=0

  [Service]
  Type=exec
  KillMode=process
  Environment=LOGGING="--log-level=info"
  ExecStart=/usr/bin/podman $LOGGING system service --time=1800

  [Install]
  WantedBy=multi-user.target
  EOF
  
  systemctl --user daemon-reload
  systemctl restart --user podman.socket

On `macOS` you need to run this in the VM (use `podman machine ssh`).