[WIP] File watch

[johnmccabe]

Description

Adds a --watch flag to the up command which will watch the filesystem for changes and trigger an up command, this includes a 500ms debounce interval to avoid unnecessary builds when many files change in quick succession.

Ignores changes some standard dirs, build, template, .git, and some temp files ~, can be appended to with the ignore-dir and ignore-suffix args.

Currently does not honour filter argument when working in a multi function dir.

Changes are watched relative to the pwd.

Motivation and Context

• [x] This fixes #472

How Has This Been Tested?

Tested locally on Windows10.

Needs feedback from Linux/OSX users.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I've read the CONTRIBUTION guide
• [ ] I have signed-off my commits with git commit -s
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[derek[bot]]

Thank you for your contribution. I've just checked and your commit doesn't appear to be signed-off. That's something we need before your Pull Request can be merged. Please see our contributing guide. Tip: if you only have one commit so far then run: git commit --amend --signoff and then git push --force.

[alexellis]

Excited to see this John, thank you for working on it again.

Currently does not honour filter argument when working in a multi function dir.

^ can you explain what this means in practice?

You'd also mentioned something on DM to me about there not being a clean separation or similar? I wasn't sure what you were referring do. Was that meaning > 1 function in a stack.yml file?

[alexellis]

I feel like the watch should do an initial build?

alex@alexx:~/go/src/github.com/openfaas/faas-cli/tests$ faas-cli new --lang node12 quick
2020/02/09 19:53:17 No templates found in current directory.
2020/02/09 19:53:17 Attempting to expand templates from https://github.com/openfaas/templates.git
2020/02/09 19:53:19 Fetched 19 template(s) : [csharp csharp-armhf dockerfile go go-armhf java11 java11-vert-x java8 node node-arm64 node-armhf node12 php7 python python-armhf python3 python3-armhf python3-debian ruby] from https://github.com/openfaas/templates.git
Folder: quick created.
  ___                   _____           ____
 / _ \ _ __   ___ _ __ |  ___|_ _  __ _/ ___|
| | | | '_ \ / _ \ '_ \| |_ / _` |/ _` \___ \
| |_| | |_) |  __/ | | |  _| (_| | (_| |___) |
 \___/| .__/ \___|_| |_|_|  \__,_|\__,_|____/
      |_|


Function created in folder: quick
Stack file written: quick.yml

Notes:
You have created a new function which uses Node.js 12 (TLS) and the OpenFaaS
of-watchdog which gives greater control over HTTP responses.

npm i --save can be used to add third-party packages like request or cheerio
npm documentation: https://docs.npmjs.com/

Unit tests are run at build time via "npm run", edit package.json to specify 
how you want to execute them.

alex@alexx:~/go/src/github.com/openfaas/faas-cli/tests$ faas-cli up --skip-push --watch
Unknown flag: --watch
alex@alexx:~/go/src/github.com/openfaas/faas-cli/tests$ ../faas-cli up --skip-push --watch
2020/02/09 19:53:31 Watching:  /home/alex/go/src/github.com/openfaas/faas-cli/tests

[johnmccabe]

If you set a watch in a multi-function dir the --filter does not limit change watches to just that function.

[alexellis]

This is what happened when editing the js file:

alex@alexx:~/go/src/github.com/openfaas/faas-cli/tests$ ../faas-cli up --skip-push --watch
2020/02/09 19:53:31 Watching:  /home/alex/go/src/github.com/openfaas/faas-cli/tests
	2020/02/09 19:54:09 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swx": REMOVE
2020/02/09 19:54:09 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": REMOVE
2020/02/09 19:54:09 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": CREATE
2020/02/09 19:54:09 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": WRITE
2020/02/09 19:54:09 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": CHMOD
2020/02/09 19:54:09 Error detecting change: please provide a valid --image name for your Docker image
2020/02/09 19:54:12 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": WRITE
2020/02/09 19:54:13 Error detecting change: please provide a valid --image name for your Docker image
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/4913": REMOVE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js": RENAME
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js~": CREATE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js": CREATE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js": WRITE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js": CHMOD
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js": CHMOD
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": WRITE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/handler.js~": REMOVE
2020/02/09 19:54:14 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/quick/.handler.js.swp": REMOVE
2020/02/09 19:54:15 Error detecting change: please provide a valid --image name for your Docker image

[johnmccabe]

Yep, WIP has debug logging for fs events.

[alexellis]

Edited the quick.yml file and added my Docker Hub prefix, then got this:

2020/02/09 19:55:12 changed: "/home/alex/go/src/github.com/openfaas/faas-cli/tests/.quick.yml.swp": REMOVE
2020/02/09 19:55:12 Error detecting change: please provide a valid --image name for your Docker image

Think it's because I missed -f quick.yml - so maybe --watch should fail in that circumstance?

[alexellis]

What happens, if there's a build in progress, but it's slow i.e. pulling node_modules and I save again, but outside of the debounce time?

[alexellis]

Removing intermediate container e986af75e6cb
 ---> 10b71cc0b220
Step 25/29 : ENV exec_timeout="10s"
 ---> Running in 71f3fbe51123
 ---> Running in 3af82da8ad48
Removing intermediate container a773fa64453e
 ---> d3cc3b2936ea
Step 28/29 : HEALTHCHECK --interval=3s CMD [ -e /tmp/.lock ] || exit 1
Removing intermediate container 71f3fbe51123
 ---> 213933305019
Step 26/29 : ENV write_timeout="15s"
Removing intermediate container 3af82da8ad48
 ---> 4ef7cffea8ff
Step 26/29 : ENV write_timeout="15s"
 ---> Running in 069815cdda02
 ---> Running in e405854e92d3
 ---> Running in d1bdf101cb4a
Removing intermediate container 069815cdda02
 ---> 6f76201dd4a6
Step 29/29 : CMD ["fwatchdog"]
Removing intermediate container e405854e92d3
 ---> 3d712333c80e
Step 27/29 : ENV read_timeout="15s"
Removing intermediate container d1bdf101cb4a
 ---> dd5f59c71e6b
Step 27/29 : ENV read_timeout="15s"
 ---> Running in 509ddc2fee52
 ---> Running in 922d28768b78
 ---> Running in 13fb28f4954a
Removing intermediate container 509ddc2fee52
 ---> d35b7f05eed5
Successfully built d35b7f05eed5
Successfully tagged alexellis2/quick-test:latest
Image: alexellis2/quick-test:latest built.
[0] < Building quick done in 98.93s.
[0] Worker done.

Total build time: 98.93s

Might be running several concurrent builds? It's just one function here.