Hi Nick
If you are really serious about pushing corrections to the Fabric/Python
documentation, you could just grab a random fabric 'Getting Started'
page and look at the first code line (more or less like I did below).
Since there are so many variations (2 pythons X 3 Fabrics = 6 possible
starting points), just specifying the environment of the first 'Hello
World' example would be a big help.
This is not so easy. With two possibilities of python and three
possibilities of the fabric library, there are six combinations of
starting points before the '>>> from fabric import Connection' line.
The documentation for fabric is quite good looking. However, looking at
Fabric Overview and Tutorial
(http://docs.fabfile.org/en/1.14/tutorial.html), the 5th line into that
document recommends looking at the 'usage documentation'
(http://docs.fabfile.org/en/1.14/index.html#usage-docs). This is a short
page and on the 4th line it recommends looking at the Overview and
Tutorial (http://docs.fabfile.org/en/1.14/tutorial.html), which of
course is the page I just came from. This 'going in circles' is a
metaphor for a lot of the fabric documentation.
----------
Ok, I'm cheating now. I talked with my son for awhile this morning. He
has several remote deployments going in Europe - all using Fabric. I
mentioned that when I put in the @task decorator as you had recommended,
I got an error complaining about "TypeError: Tasks must have an initial
Context argument!". This was a new error for me!!!
My son explained that I needed a few lines at the top of the fabfile.py
to define the environment 'Context' where the command (hello world) will
execute. I said I already was using virtualenv and had the (env) in
front of my shell prompt.
He said that the 'env' I was using was just for Python, not for Fabric.
Fabric needs an *Additional* environment ('Context') set up. In the
Getting Started document, there is no mention of 'Context' prior to the
first code line.
With that new clue, I scrambled off into Google with a new series of
searches - looking for 'Context' in combination with fabric, python, etc.
I found a different Overview and Tutorial
(http://docs.fabfile.org/en/1.4.1/tutorial.html). There was a warning
bar saying that I was not viewing the latest version - I should get
1.12.1 - which I did.
This much newer Overview and Tutorial looked quite familiar
(http://docs.fabfile.org/en/1.12.1/tutorial.html) but it is not quite
the same as the 1.14 referenced above.
The first code lines, to be typed into fabfile.py:
*def hello():**
**Â Â Â print("Hello world!")*
of course do not work:
(env) air:fabric-test bobgus$ fab hello
No idea what 'hello' is!
Ok, I can put in the @task decorator as you suggested initially
*@task
def hello():**
****Â Â Â print("Hello world!")*
(env) air:fabric-test bobgus$ fab hello
...
NameError: name 'task' is not defined
Ok, we have seen that before. By now (after days...) I know that @task
must be imported.
I can add the line "from fabric.api import task" above the @task line.
*from fabric.api import task*
*@task**
**def hello():**
****Â Â Â print("Hello world!")**
***
This doesn't work either
(env) air:fabric-test bobgus$ fab hello
...
ModuleNotFound: No module named 'fabric.api'
I have seen that error before too. It means I am trying to execute
Fabric <2 code with Fabric 2+ library.
I can change the import statement to: "*from fabric import task*"
But then I get another series of errors:
(env) air:fabric-test bobgus$ fab hello
...
IndexError: pop from empty list
During handling of the above exception, another exception occurred:
...
TypeError: Tasks must have an initial Context argument!
----------------------------------------------------------------------------------
Looking with Google, I found this stackoverflow comment:
https://stackoverflow.com/questions/52822922/fabric-python-3-what-is-context-and-what-does-it-have-to-contain-and-why-do
It suggests using a dummy argument to fool Fabric into doing the right
thing...
So, I change my code to:
*from fabric import task*
***@task**
****def hello(dummy):**
******Â Â Â print("Hello world!")**
*****
**
And, presto, I get a 'correct' output:
(env) air:fabric-test bobgus$ fab hello
Hello world!
Even though I get the correct answer, I don't think this is really the
correct approach.
I haven't put in any Context definition, I just put in some characters
that don't refer to anything else (unless the word 'dummy' is a reserved
word in the Fabric/Python world).
I think the discussion has moved from incomplete documentation to buggy
code.
Sincerely, Bob Gustafson
Post by Nick TimkovichYeah, the >>> implies you're at the Python REPL, and the page I linked
you to is a few pages into learning to use Fabric; so it's going to
assume you installed the library. If you already know Tcl/Expect, I'm
sure you can bang out a script to do your task at hand, and if you
need it now and don't have time to pick up Python and Fabric on top of
it, that sounds like your best option.
When you get some spare time, there are a bunch of great tutorials
that can help you with the syntax (which may be easy), and also how
Python is loading/running scripts/packages/modules (which is usually
less obvious), which Fabric then uses to find a 'fabfile' package. I
haven't heard of Tidelift, but yeah, I feel your pain that a lot
of training sites which were once free are now pay-only (or very
expertly hide the free options, *coughcodecademycough*). Fortunately,
the gigantic popularity of Python means new, free content is always
being created, so some searching may help (I'm hesitant to cite
anything in particular because I haven't looked at any recently)
I was curious what examples/documentation you were following along
with originally, however, because it seemed incomplete, even for the
3-4 lines that you had. It would be nice to correct it so others
aren't misled in the future.
Hi Nick
Yes, 'incomplete' is a charitable description.
I have zit knowledge of python. Perhaps this has been accidental
good luck. My favorite languages over the decades have been
Fortransit, Pascal, Ruby, and lately Nim.
Using your linked example ('Getting Started'..), starting with the
  >>> from fabric import Connection
There seems to be a lot that is assumed to have been done by the
reader. The >>> probably means that the reader has already typed
'python' to jump into an interactive Python session, but this is
not mentioned.
Also, just typing 'python' is not sufficient, as the following
lines may not work under Python 2.7 or Python 3.7. Which Python is
invoked depends on what has been typed before.
Also, 'fabric' is used in the code line. This library must have
been loaded or the line will not work. Again, loading fabric
beforehand is not mentioned. Also 'fabric' comes in several
versions <2, 2, and a version not recommended - 3.
I see from the libraries, and my experience with Sage, that lots
of good things have been done with Python. However, the state of
python documentation available on the internet leaves a lot
unsaid. Perhaps it is all a game to get new users to buy a
subscription to Tidelift.
At this point, for me, coding up 'expect' and fabric in Nim seems
easier than continuing this frustration.
Best regards
Bob G
Post by Nick TimkovichFor the `fab` tool to pick up functions in your fabfile
decorator (specifically fabric.task). See
http://docs.fabfile.org/en/2.4/getting-started.html#addendum-the-fab-command-line-tool
What documentation are you following? It sounds fairly incomplete
and could be fixed.
Nick
I am running on a Mac air with Mojave os 10.14.1.
I installed python with homebrew
Also using virtualenv and the folder fabric-test
cd fabric-test
air:fabric-test bobgus$ ls
env   fabfile.py
air:fabric-test bobgus$ source env/bin/activate
(env) air:fabric-test bobgus$ which python
/Users/bobgus/fabric-test/env/bin/python
(env) air:fabric-test bobgus$ python -V
Python 3.7.0
(env) air:fabric-test bobgus$ fab -V
Fabric 2.4.0
Paramiko 2.4.2
Invoke 1.2.0
(env) air:fabric-test bobgus$ cat fabfile.py
#!/usr/bin/env python
  print("Welcome to fabric running on python 3")
  run("uptime")fab
--------------------- testing -------
(env) air:fabric-test bobgus$ fab uptime
No idea what 'uptime' is!
(env air:fabric-test bobgus$ fab welcome
No idea what 'welcome' is!
--------------------------------------
I must be doing something wrong here..
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