davidcaron opened a new pull request #13793:
URL: https://github.com/apache/airflow/pull/13793
Iterable values in `cli.attach(..., stream=True)` are not necessarily single
lines.
Lines can be merged together or split because of buffering.
When this split happens just before the last newline character, the returned
value of `execute` is an empty byte string.
Also, fix the return type annotation (the return type is not changed, only
the annotation).
I used these files to recreate the issue:
`Dockerfile`
```dockerfile
FROM python:3.8-slim-buster
WORKDIR /code
ADD main.py .
CMD [ "python", "main.py" ]
```
`main.py`
```python
from random import randint
for _ in range(randint(1, 100)):
print(f"output")
print("last_line")
```
`script.py`
```python
from docker import APIClient
cli = APIClient()
def run_image():
container = cli.create_container(
command="python main.py",
host_config=cli.create_host_config(auto_remove=False),
image="docker-bug",
tty=True,
)
lines = cli.attach(container=container["Id"], stdout=True, stderr=True,
stream=True)
cli.start(container["Id"])
line = list(lines)[-1]
cli.wait(container["Id"])
print("--- LAST LINES ---")
print(repr(line))
print(repr(cli.logs(container=container["Id"], tail=1).strip()))
cli.remove_container(container["Id"])
if __name__ == "__main__":
for i in range(1000):
run_image()
```
When running:
```bash
$ docker build -t docker-bug .
$ python script.py
```
The output will look something like:
```
--- LAST LINES ---
b'output\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\nlast_line\r\n'
b'last_line'
--- LAST LINES ---
b'output\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\noutput\r\nlast_line\r\n'
b'last_line'
--- LAST LINES ---
b'output\r\noutput\r\nlast_line\r\n'
b'last_line'
```
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