# Hacking on osbuild-composer

## Virtual Machine

*osbuild-composer* cannot be run from the source tree, but has to be installed
onto a system. We recommend doing this by building rpms, with:

```
dnf install fedora-packager
dnf builddep osbuild-composer
make rpm
```

This will build rpms from the latest git HEAD (remember to commit changes), for
the current operating system, with a version that contains the commit hash. The
packages end up in `./rpmbuild/RPMS/$arch`.

RPMS are easiest to deal with when they're in a dnf repository. To turn this
directory into a dnf repository and serve it on localhost:8000, run:

```
createrepo_c ./rpmbuild/RPMS/x86_64
python3 -m http.server --directory ./rpmbuild/RPMS/x86_64 8000
```

To start a ephemeral virtual machine using this repository, run:

```
tools/deploy-qemu IMAGE tools/deploy/test
```

`IMAGE` has to be a path to an cloud-init-enabled image matching the host
operating system, because that's what the packages were built for above.
Note that the Fedora/RHEL cloud images might be too small for some tests
to pass. Run `qemu-img resize IMAGE 10G` to grow them, cloud-init's growpart
module will grow the root partition automatically during boot. 

The second argument points to a directory from which cloud-init user-data is
generated (see `tools/gen-user-data` for details). The one given above tries to
mimic what is run on *osbuild-composer*'s continuous integration
infrastructure, i.e., installing `osbuild-composer-tests` and starting the
service.

The virtual machine uses qemu's [user networking](https://wiki.qemu.org/Documentation/Networking#User_Networking_.28SLIRP.29), forwarding port 22 to
the host's 2222 and 443 to 4430. You can log into the running machine with

```
ssh admin@localhost -p 2222
```

The password is `foobar`. Stopping the machine loses all data.

For a quick compile and debug cycle, we recommend iterating code using thorough
unit tests before going through the full workflow described above.

## Containers

*osbuild-composer* and *osbuild-composer-worker* can be run using Docker
containers. Building and starting containers is generally faster than building
RPMs and installing them in a VM, so this method is more convenient for
developing and testing changes quickly. However, using this method has several
downsides:
- It doesn't build the RPMs so the `.spec` file isn't tested.
- The environment is quite different from production (e.g., installation paths,
  privileges and permissions).
- The setup is not complete for all required services, so some functionality
  isn't available for testing this way (e.g., Koji Hub and all its dependent
  services).

The containers are a good way to quickly test small changes, but before
submitting a Pull Request, it's recommended to run through all the tests using
the [Virtual Machine](#virtual-machine) setup described above.

### Build and run

To build the containers run:

```
docker-compose build
```

To start the containers run:

```
docker-compose up
```

You can send requests to the *osbuild-composer* container by entering the devel
container and running:

```
curl -k --cert /etc/osbuild-composer/client-crt.pem --key /etc/osbuild-composer/client-key.pem https://172.30.0.10:8080/api/composer-koji/v1/status
```

To rebuild the containers after a change, add the `--build` flag to the `docker-compose` command:

```
docker-compose up --build
```

## Shortening the loop

For some components, it is possible to install distribution packages first and then only to replace binaries which may or may not work for smaller changes.

```
systemctl stop osbuild-composer.service osbuild-composer.socket osbuild-local-worker.socket
make build && sudo install -m755 bin/osbuild-composer bin/osbuild-worker /usr/libexec/osbuild-composer/
systemctl start osbuild-composer.socket osbuild-local-worker.socket
```

## Accessing Cloud API

You can use curl to access the Cloud API:

```
curl --unix-socket /run/cloudapi/api.socket -XGET http://localhost/api/image-builder-composer/v2/openapi
```