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https://github.com/garethr/pycnab
Python library for manipulating Cloud Native Application Bundles
https://github.com/garethr/pycnab
cnab python python3
Last synced: 27 days ago
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Python library for manipulating Cloud Native Application Bundles
- Host: GitHub
- URL: https://github.com/garethr/pycnab
- Owner: garethr
- License: other
- Created: 2018-12-31T18:39:06.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2021-04-20T18:10:05.000Z (over 3 years ago)
- Last Synced: 2024-10-04T13:18:17.198Z (about 2 months ago)
- Topics: cnab, python, python3
- Language: Python
- Size: 52.7 KB
- Stars: 21
- Watchers: 4
- Forks: 3
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-cnab - pycnab - Python CNAB Library (Community-Projects / Docker-App)
README
# Python CNAB Library
_Work-in-progress_ library for working with [CNAB](https://cnab.io/) in Python.
There are probably three main areas of interest for a CNAB client:
1. Handling the `bundle.json` format ([101](https://github.com/deislabs/cnab-spec/blob/master/101-bundle-json.md))
2. Building invocation images ([102](https://github.com/deislabs/cnab-spec/blob/master/102-invocation-image.md))
3. Running actions against a CNAB ([103](https://github.com/deislabs/cnab-spec/blob/master/103-bundle-runtime.md))
Claims and Signing are optional but will be worked on once the above are stable.
## Installation
The module is published on [PyPi](https://pypi.org/project/cnab/) and can be installed from there.
```bash
pip install cnab
```
## Parsing `bundle.json`
Nothing too fancy here, the `Bundle` class has a `from_dict` static method which
builds a full `Bundle` object.
```python
import json
from cnab import Bundle
with open("bundle.json") as f:
data = json.load(f)
bundle = Bundle.from_dict(data)
```
This could for example be used for validation purposes, or for building user interfaces for `bundle.json` files.
## Describing `bundle.json` in Python
You can also describe the `bundle.json` file in Python. This will correctly validate the
structure based on the current specification and would allow for building a custom DSL or other
user interface for generating `bundle.json` files.
```python
from cnab import Bundle, InvocationImage
bundle = Bundle(
name="hello",
version="0.1.0",
invocation_images=[
InvocationImage(
image_type="docker",
image="technosophos/helloworld:0.1.0",
digest="sha256:aaaaaaa...",
)
],
)
print(bundle.to_json())
```
## Running CNABs
The module supports running actions on a CNAB, using the `docker` driver.
```python
from cnab import CNAB
# The first argument can be a path to a bundle.json file, a dictionary
# or a full `Bundle` object
app = CNAB("fixtures/helloworld/bundle.json")
# list available actions
print(app.actions)
# list available parameters
print(app.parameter)
# run the install action
print(app.run("install"))
# run the install action specifying a parameters
print(app.run("install", parameters={"port": 9090}))
# Many applications will require credentials
app = CNAB("fixtures/hellohelm/bundle.json")
# list required credentials
print(app.credentials)
# Here we pass the value for the required credential
# in this case by reading the existing configuration from disk
with open("/home/garethr/.kube/config") as f:
print(app.run("status", credentials={"kubeconfig": f.read()}))
```
Note that error handling for this is very work-in-progress.
## Working with invocation images
`pycnab` also has a class for working with invocation images.
```python
from cnab import CNABDirectory
directory = CNABDirectory("fixtures/invocationimage")
# Check whether the directory is valid
# Raises `InvalidCNABDirectory` exception if invalid
directory.valid()
# Returns the text of the associated README file if present
directory.readme()
# Returns the text of the associated LICENSE file if present
directory.license()
```
## Thanks
Thanks to [QuickType](https://quicktype.io/) for bootstrapping the creation of the Python code for manipulating `bundle.json` based on the current JSON Schema.