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Luciano Ramalho
2021-09-27 19:55:48 -03:00
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20-futures/getflags/README.adoc
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= Experimenting with the `flags2*` examples
The `flags2*` examples enhance the `flags*` examples with error handling and reporting.
Therefore, we need a server that generates errors and delays to test them.
Therefore, we need a server that generates errors and delays to experiment with them.
The main reason for these instructions is to document how to configure one such server
in your machine, and how to run the clients to use it.
in your machine, and how to tell the `flags2*` clients to access it.
The other reason is to alert of an installation step that MacOS users sometimes overlook.
Contents:
@@ -19,14 +18,14 @@ Contents:
If you don't already have a local HTTP server for testing,
here are the steps to experiment with the `flags2*` examples
using just the Python ≥ 3.9 distribution and
using just the Python ≥ 3.9 distribution:
. Clone or download the https://github.com/fluentpython/example-code-2e[_Fluent Python 2e_ code repository] (this repo!).
. Open your shell and go to the _20-futures/getflags/_ directory of your local copy of the repository (this directory!)
. Unzip the _flags.zip_ file, creating a _flags_ directory at _20-futures/getflags/flags/_.
. Open a second shell, go to the _20-futures/getflags/_ directory and run `python3 -m http.server`. This will start a `ThreadingHTTPServer` listening to port 8000, serving the local files. If you open the URL http://localhost:8000/flags/[http://localhost:8000/flags/] with your browser, you'll see a long list of directories named with two-letter country codes from `ad/` to `zw/`.
. Now you can go back to the first shell and run the _flags2*.py_ examples with the default `--server LOCAL` option.
. To test with the `--server DELAY` option, go to _20-futures/getflags/_ and run `python3 slow_server.py`. This bind to port 8001 by default. It will add a .5s delay before each response.
. To test with the `--server DELAY` option, go to _20-futures/getflags/_ and run `python3 slow_server.py`. This binds to port 8001 by default. It will add a .5s delay before each response.
. To test with the `--server ERROR` option, go to _20-futures/getflags/_ and run `python3 slow_server.py 8002 --error-rate .25`.
Each request will have a 25% probability of getting a
https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/418[418 I'm a teapot] response,
@@ -52,8 +51,7 @@ https://github.com/shopify/toxiproxy[Toxiproxy] with equivalent parameters.
The `flags2*` examples provide a command-line interface.
All three scripts accept the same options,
and you can see them by running any of the scripts with the `-h` option.
<<flags2_help_demo>> shows the help text.
and you can see them by running any of the scripts with the `-h` option:
[[flags2_help_demo]]
.Help screen for the scripts in the flags2 series
@@ -91,18 +89,21 @@ One option you can't ignore is `-s/--server`: it lets you choose which HTTP serv
You can pass one of four strings to determine where the script will look for the flags (the strings are case insensitive):
`LOCAL`:: Use `http://localhost:8000/flags`; this is the default.
You should configure a local HTTP server to answer at port 8000. See <<setting_up_servers_box>> for instructions.
You should configure a local HTTP server to answer at port 8000. See <<server_setup>> for instructions.
Feel free to hit this as hard as you can. It's your machine!
`REMOTE`:: Use `http://fluentpython.com/data/flags`; that is a public website owned by me, hosted on a shared server.
Please do not pound it with too many concurrent requests.
Please do not hit it with too many concurrent requests.
The `fluentpython.com` domain is handled by the http://www.cloudflare.com/[Cloudflare] CDN (Content Delivery Network)
so you may notice that the first downloads are slower, but they get faster when the CDN cache warms
up.footnote:[Before configuring Cloudflare, I got HTTP 503 errors--Service Temporarily Unavailable--when
testing the scripts with a few dozen concurrent requests on my inexpensive shared host account. Now those errors are gone.]
`DELAY`:: Use `http://localhost:8001/flags`; a server delaying HTTP responses should be listening to port 8001. I wrote _slow_server.py_ to make it easier to experiment. You'll find it in the _20-futures/getflags/_ directory of the https://github.com/fluentpython/example-code-2e[_Fluent Python 2e_ code repository]. See <<setting_up_servers_box>> for instructions.
`DELAY`:: Use `http://localhost:8001/flags`; a server delaying HTTP responses should be listening to port 8001.
I wrote _slow_server.py_ to make it easier to experiment. See <<server_setup>> for instructions.
`ERROR`:: Use `http://localhost:8002/flags`; a server introducing HTTP errors and delaying responses should be installed at port 8002. Running _slow_server.py_ is an easy way to do it. See <<setting_up_servers_box>>.
`ERROR`:: Use `http://localhost:8002/flags`; a server introducing HTTP errors and delaying responses should be installed at port 8002.
Running _slow_server.py_ is an easy way to do it. See <<server_setup>>.
[[macos_certificates]]
== Install SSL Certificates (for MacOS)