Port infra-rebuild to Python

Do this for a nicer developer experience in a safer language, which has
nice libraries available to e.g. build command line interfaces (e.g.
click).

Set minimum Python version to 3.10 to support match statements.

src/infra_rebuild/cli/__init__.py

@@ -1,9 +1,52 @@
 import click
 
+from infra_rebuild import operations
 from infra_rebuild.__about__ import __version__
 
 
 @click.group(context_settings={"help_option_names": ["-h", "--help"]}, invoke_without_command=True)
 @click.version_option(version=__version__, prog_name="infra-rebuild")
 def infra_rebuild():
-    click.echo("Hello world!")
+    pass
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def build(hosts):
+    operations.run("build", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def build_vm(hosts):
+    operations.run("build-vm", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def build_vm_with_bootloader(hosts):
+    operations.run("build-vm-with-bootloader", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def switch(hosts):
+    operations.run("switch", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def boot(hosts):
+    operations.run("boot", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def test(hosts):
+    operations.run("test", hosts)
+
+
+@infra_rebuild.command()
+@click.argument("hosts")
+def reboot(hosts):
+    operations.run("reboot", hosts)

src/infra_rebuild/msg/__init__.py

@@ -0,0 +1,13 @@
+import click
+
+
+def info(message):
+    click.echo(click.style(message, bold=True, fg="bright_blue"))
+
+
+def warning(message):
+    click.echo(click.style(message, bold=True, fg="bright_yellow"), err=True)
+
+
+def error(message):
+    click.echo(click.style(message, bold=True, fg="bright_red"), err=True)

src/infra_rebuild/operations/__init__.py

@@ -0,0 +1,146 @@
+import json
+import os
+import subprocess
+import sys
+
+from infra_rebuild import msg
+
+
+def run(operation, hosts):
+    act_remotely = False
+    reboot = False
+    match operation:
+        case "build" | "build-vm" | "build-vm-with-bootloader":
+            actual_operation = operation
+        case "switch" | "boot" | "test":
+            act_remotely = True
+            actual_operation = operation
+        case "reboot":
+            act_remotely = True
+            actual_operation = "boot"
+            reboot = True
+        case _:
+            msg.error("Internal Error: The given operation isn't valid.")
+            sys.exit(1)
+
+    for host_string in hosts.split(","):
+        host = host_string.strip()
+        if not host:
+            msg.warning("Skipping empty string provided for host.")
+            continue
+
+        if act_remotely:
+            remote(actual_operation, host, reboot)
+        else:
+            local(actual_operation, host)
+
+
+def local(operation, host):
+    msg.info(f"Running nixos-rebuild {operation} for {host}...")
+    subprocess.run(
+        ["nixos-rebuild", operation, "--flake", f".#{host}"],  # noqa: S607, S603 - can't know what the users system looks like, maybe do some kind of validation for the given host in the future?
+        check=False
+    )  # fmt: skip
+
+
+def remote(operation, host, reboot=False):  # noqa: FBT002 - having reboot as a Boolean positional argument is fine I think # fmt: skip
+    config = None
+    try:
+        with open("deployment_configuration.json") as config_file:
+            try:
+                config = json.load(config_file)
+            except json.JSONDecodeError:
+                msg.warning(
+                    "The deployment_configuration.json is not a valid JSON document and therefore it can't be used to retrieve configuration values."  # noqa: E501
+                )
+    except FileNotFoundError:
+        msg.warning(
+            "No deployment_configuration.json exists and therefore it can't be used to retrieve configuration values."
+        )
+    except OSError:
+        msg.warning(
+            "Couldn't open deployment_configuration.json and therefore it can't be used to retrieve configuration values."  # noqa: E501
+        )
+
+    target_hostname = None
+    if config:
+        try:
+            target_hostname = config["hosts"][host]["targetHostname"]
+        except KeyError:
+            pass
+    if not target_hostname:
+        nix_config_fqdn = subprocess.run(
+            ["nix", "eval", "--raw", f".#nixosConfigurations.{host}.config.networking.fqdn"],  # noqa: S607, S603 - can't know what the users system looks like, maybe do some kind of validation for host in the future?
+            capture_output=True,
+            text=True,
+            check=False,
+        )  # fmt: skip
+        if nix_config_fqdn.returncode == 0 and nix_config_fqdn.stdout:
+            target_hostname = nix_config_fqdn.stdout
+    if not target_hostname:
+        msg.error(f"Couldn't determine target hostname for {host}.")
+        msg.error(
+            "You either need to set targetHostname for this host in the deployment_configuration.json or have an FQDN available in the NixOS configuration of this host, which then gets used for the target hostname."  # noqa: E501
+        )
+        msg.error(f"Skipping {host}.")
+        return
+
+    target_user = None
+    if config:
+        try:
+            target_user = config["hosts"][host]["targetUser"]
+        except KeyError:
+            pass
+    if config and not target_user:
+        try:
+            target_user = config["default"]["targetUser"]
+        except KeyError:
+            pass
+
+    target_port = None
+    if config:
+        try:
+            target_port = config["hosts"][host]["targetPort"]
+        except KeyError:
+            pass
+    if config and not target_port:
+        try:
+            target_port = config["default"]["targetPort"]
+        except KeyError:
+            pass
+
+    target_host = target_hostname
+    if target_user:
+        target_host = f"{target_user}@{target_host}"
+
+    ssh_opts = None
+    if target_port:
+        ssh_opts = f"-o Port={target_port}"
+
+    nixos_rebuild_env = os.environ.copy()
+    if ssh_opts:
+        nixos_rebuild_env["NIX_SSHOPTS"] = ssh_opts
+
+    if target_port:
+        msg.info(f"Running nixos-rebuild {operation} for {host} on {target_host}:{target_port}...")
+    else:
+        msg.info(f"Running nixos-rebuild {operation} for {host} on {target_host}...")
+
+    nixos_rebuild = subprocess.run(
+        ["nixos-rebuild", operation, "--flake", f".#{host}", "--target-host", target_host, "--use-substitutes", "--use-remote-sudo"],  # noqa: S607, S603, E501 - can't know what the users system looks like, maybe do some kind of validation for the given host in the future?, not breaking up the command makes it more readable
+        env=nixos_rebuild_env,
+        check=False,
+    )  # fmt: skip
+
+    if reboot and nixos_rebuild.returncode == 0:
+        msg.info(f"Rebooting {target_hostname}...")
+        if ssh_opts:
+            subprocess.run(
+                ["ssh", ssh_opts, target_host, "sudo", "systemctl", "reboot"],  # noqa: S607, S603 - can't know what the users system looks like, maybe do some kind of validation for the given host in the future?
+                check=False
+            )  # fmt: skip
+        else:
+            subprocess.run(
+                ["ssh", target_host, "sudo", "systemctl", "reboot"],  # noqa: S607, S603 - can't know what the users system looks like, maybe do some kind of validation for the given host in the future?
+                check=False,
+            )  # fmt: skip