Skip to content

Commit

Permalink
Provide method to update kubeconfigs of known formats (#21)
Browse files Browse the repository at this point in the history
  • Loading branch information
addyess authored Jun 20, 2024
1 parent 7ce9dc5 commit 7ad0eae
Show file tree
Hide file tree
Showing 2 changed files with 114 additions and 28 deletions.
108 changes: 80 additions & 28 deletions charms/kubernetes_snaps.py
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,8 @@ class ExternalCloud(Protocol):
"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305",
]


JUJU_CLUSTER = "juju-cluster"
JUJU_CONTEXT = "juju-context"
BASIC_SNAPS = ["kubectl", "kubelet", "kube-proxy"]
CONTROL_PLANE_SNAPS = [
"kube-apiserver",
Expand Down Expand Up @@ -451,35 +452,86 @@ def configure_services_restart_always(control_plane=False):
check_call(["systemctl", "daemon-reload"])


def create_kubeconfig(dest, ca, server, user, token):
ca_base64 = b64encode(ca.encode("utf-8")).decode("utf-8")
kubeconfig = {
"apiVersion": "v1",
"kind": "Config",
"clusters": [
{
"cluster": {"certificate-authority-data": ca_base64, "server": server},
"name": "juju-cluster",
}
],
"contexts": [
{
"context": {"cluster": "juju-cluster", "user": user},
"name": "juju-context",
}
],
"current-context": "juju-context",
"preferences": {},
"users": [{"name": user, "user": {"token": token}}],
}
def update_kubeconfig(
dest: os.PathLike,
ca: Optional[str] = None,
server: Optional[str] = None,
user: Optional[str] = None,
token: Optional[str] = None,
) -> Path:
"""Update a kubeconfig file with the given parameters. If the file does not
exist, it will be created. If the file does exist, it will be updated with
the given parameters.
os.makedirs(os.path.dirname(dest), exist_ok=True)
Args:
dest: The path to the kubeconfig file.
ca: The certificate authority data.
server: The server URL.
user: The user name.
token: The user token.
Raises:
FileNotFoundError: If the kubeconfig file does not exist.
KeyError: If the kubeconfig file is not in the expected format.
AssertionError: If the kubeconfig file is not in the expected format.
# Write to temp file so we can replace dest atomically
temp_dest = dest + ".new"
with open(temp_dest, "w") as f:
yaml.safe_dump(kubeconfig, f)
os.replace(temp_dest, dest)
Returns:
Path: the updated kubeconfig file.
"""
target, target_new = Path(dest), Path(f"{dest}.new")
if all(f is None for f in (ca, server, user, token)):
log.warning("Nothing provided to update kubeconfig %s", dest)
return target
if any(f is None for f in (ca, server, user, token)):
log.info("Updating existing kubeconfig %s", dest)
if not target.exists():
raise FileNotFoundError(f"Cannot update kubeconfig: {target}")
content = yaml.safe_load(target.read_text())
assert content["clusters"][0]["name"] == JUJU_CLUSTER
assert content["contexts"][0]["name"] == JUJU_CONTEXT
assert content["contexts"][0]["context"]["cluster"] == JUJU_CLUSTER
else:
log.info("Creating wholly new kubeconfig: %s", dest)
content = {
"apiVersion": "v1",
"kind": "Config",
"clusters": [
{
"cluster": {"certificate-authority-data": None, "server": None},
"name": JUJU_CLUSTER,
}
],
"contexts": [
{
"context": {"cluster": JUJU_CLUSTER, "user": None},
"name": JUJU_CONTEXT,
}
],
"current-context": JUJU_CONTEXT,
"preferences": {},
"users": [{"name": None, "user": {"token": None}}],
}

if ca:
ca_base64 = b64encode(ca.encode("utf-8")).decode("utf-8")
content["clusters"][0]["cluster"]["certificate-authority-data"] = ca_base64
if server:
content["clusters"][0]["cluster"]["server"] = server
if user:
content["contexts"][0]["context"]["user"] = user
content["users"][0]["name"] = user
if token:
content["users"][0]["user"]["token"] = token
target_new.parent.mkdir(mode=0o755, parents=True, exist_ok=True)
target_new.write_text(yaml.safe_dump(content))
target_new.chmod(0o600)
target_new.rename(target)
return target


def create_kubeconfig(dest, ca, server, user, token):
"""Create a kubeconfig file with the given parameters."""
return update_kubeconfig(dest, ca, server, user, token)


def create_service_account_key():
Expand Down
34 changes: 34 additions & 0 deletions tests/unit/test_kubernetes_snaps.py
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,40 @@ def external_cloud(request):
yield cloud


def test_create_kubeconfig(tmp_path):
path = tmp_path / "kubeconfig"
created = kubernetes_snaps.create_kubeconfig(
path, "ca-data", "https://192.168.0.1", "test-user", "test-token"
)
assert created == path
assert created.exists()
assert (created.stat().st_mode & 0o777) == 0o600
text = created.read_text()
assert "Y2EtZGF0YQ==" in text
assert "https://192.168.0.1" in text
assert "test-user" in text
assert "test-token" in text

updated = kubernetes_snaps.update_kubeconfig(path, "new-ca-data")
assert updated == path
assert updated.exists()
assert (updated.stat().st_mode & 0o777) == 0o600
text = updated.read_text()
assert "bmV3LWNhLWRhdGE=" in text
assert "https://192.168.0.1" in text
assert "test-user" in text
assert "test-token" in text


def test_update_kubeconfig_no_file(tmp_path):
path = tmp_path / "kubeconfig"
nothing = kubernetes_snaps.update_kubeconfig(path)
assert not nothing.exists()

with pytest.raises(FileNotFoundError):
kubernetes_snaps.update_kubeconfig(nothing, ca="new-ca-data")


@mock.patch("charms.kubernetes_snaps.configure_kubernetes_service")
@mock.patch("charms.kubernetes_snaps.Path")
def test_configure_kubelet(
Expand Down

0 comments on commit 7ad0eae

Please sign in to comment.