Add support for HTTP status check with wget

[capripot]

Add support for HTTP status check with wget, shipped with Alpine through busybox.

Test if an API is up:
./wait-for http://www.eficode.com:80/ping -- echo "Eficode site is up"

Within a docker-compose file:

version: '2'

services:
  db:
    image: postgres:9.4

  api:
    image: my_awesome_api

  tests:
    build: tests
    command: sh -c './wait-for http://api/ping -- jest test'
    depends_on:
      - db
      - api

[iveskins]

I just tried to use nc for this, but your solution is better..
printf "GET /-/liveness HTTP/1.0\r\nHost: waitforit\r\n\r\n" |nc -n -i 1 "$HOST" "$PORT" | head -1 | grep "HTTP/1.1 200 OK" > /dev/null 2>&1

[capripot]

@eficode Any way we could merge that?

[triusis92]

Hi @capripot ,

I tried using your adjusted script in an alpine image. Added netcat-openbsd to the build but that did not work, just kept getting timeouts when performing HTTP status checks. Is it possible to use it in an alpine image ?

[capripot]

Hi @triusis92. Just tried in the latest alpine the following

docker run -it alpine sh
wget --timeout=1 -q "https://www.google.com" -O /dev/null > /dev/null 2>&1
echo $?
# 0
wget --timeout=1 -q "https://www.thatdoesntexist.com" -O /dev/null > /dev/null 2>&1
echo $?
# 1

So I believe the script should still work. Could you share your logs/output so I can help?

[vitalets]

Until this is merged I've created wait-for-cmd that can wait for any provided command (e.g. wget):

docker run --rm vitalets/wait-for-cmd 'wget --timeout=1 -q https://www.google.com -O /dev/null > /dev/null 2>&1'

[pkraus138]

Thank you so much for this!

[Addono]

Hi @capripot , sorry for taking so long to get back to you on your PR.

I started working top-to-bottom from the list of PRs and by the time I reached yours there were some merge conflicts.

Supporting http/https makes a lot of sense, so I'm happy that you worked on this. I created a new PR #34, which is mostly your work but with some changes here and there to make it all work with some other changes which recently landed.

I'm first releasing #34 first as a beta, if anyone ends up using it, please share your experiences in that PR.

Cheers!