Docker API can’t apply json filters - json

Question

According to the https://docs.docker.com/engine/reference/api/docker_remote_api_v1.24/#/list-tasks, filter can be only used to get running containers with a particular service name. For some reason, I am getting a full list of all tasks regardless of their names or desired states. I can't find any proper examples of using curl with JSON requests with Docker API.
I'm using the following command:
A)
curl -X GET -H "Content-Type: application/json" -d '{"filters":[{ "service":"demo", "desired-state":"running" }]}' https://HOSTNAME:2376/tasks --cert ~/.docker/cert.pem --key ~/.docker/key.pem --cacert ~/.docker/ca.pem
Returns everything
B)
trying to get something working from Docker Remote API Filter Exited
curl https://HOSTNAME:2376/containers/json?all=1&filters={%22status%22:[%22exited%22]} --cert ~/.docker/cert.pem --key ~/.docker/key.pem --cacert ~/.docker/ca.pem
This one returns "curl: (60) Peer's Certificate issuer is not recognized.", so I guess that curl request is malformed.
I have asked on Docker forums and they helped a little. I'm amazed that there are no proper documentation anywhere on the internet on how to use Docker API with curl or is it so obvious and I don't understand something?

Answer 1

I should prefix this with the fact that I have never seen curl erroneously report a certificate error when in fact there was some sort of other issue in play, but I will trust your assertion that this is in fact not a certificate problem.
I thought at first that your argument to filters was incorrect, because
according to the API reference, the filters parameter is...
a JSON encoded value of the filters (a map[string][]string) to process on the containers list.
I wasn't exactly sure how to interpret map[string][]string, so I set up a logging proxy between my Docker client and server and ran docker ps -f status=exited, which produced the following request:
GET /v1.24/containers/json?filters=%7B%22status%22%3A%7B%22exited%22%3Atrue%7D%7D HTTP/1.1\r
If we decode the argument to filters, we see that it is:
{"status":{"exited":true}}
Whereas you are passing:
{"status":["exited"]}
So that's different, obviously, and I was assuming that was the source of the problem...but when trying to verify that, I ran into a curious problem. I can't even run your curl command line as written, because curl tries to perform some globbing behavior due to the braces:
$ curl http://localhost:2376/containers/json'?filters={%22status%22:[%22exited%22]}'
curl: (3) [globbing] nested brace in column 67
If I correctly quote your arguments to filter:
$ python -c 'import urllib; print urllib.quote("""{"status":["exited"]}""")'
%7B%22status%22%3A%5B%22exited%22%5D%7D
It seems to work just fine:
$ curl http://localhost:2376/containers/json'?filters=%7B%22status%22%3A%5B%22exited%22%5D%7D'
[{"Id":...
I can get the same behavior if I use your original expression and pass -g (aka --globoff) to disable the brace expansion:
$ curl -g http://localhost:2376/containers/json'?filters={%22status%22:[%22exited%22]}'
[{"Id":...
One thing I would like to emphasize is the utility of sticking a proxy between the docker client and server. If you ever find yourself asking, "how do I use this API?", an excellent answer is to see exactly what the Docker client is doing in the same situation.

Answer 2

You can create a logging proxy using socat. Here is an example.
docker run -v /var/run/docker.sock:/var/run/docker.sock -p 127.0.0.1:1234:1234 bobrik/socat -v TCP-LISTEN:1234,fork UNIX-CONNECT:/var/run/docker.sock
Then run a command like so in another window.
docker -H localhost:1234 run --rm -p 2222:2222 hello-world
This example uses docker on ubuntu.

Answer 3

A docker REST proxy can be simple like this:
https://github.com/laoshanxi/app-mesh/blob/main/src/sdk/docker/docker-rest.go
Then you can curl like this:
curl -g http://127.0.0.1:6058/containers/json'?filters={%22name%22:[%22jenkins%22]}'