segmentio / kubectl-curl

Kubectl plugin to run curl commands against kubernetes pods

kubectl-curl

Kubectl plugin to run curl commands against kubernetes pods

Motivation

Sending http requests to kubernetes pods is unnecessarily complicated, this plugin makes it easy.

The plugin creates a port forwarding from the local network to the kubernetes pod that was selected to receive the request, then instantiate a curl command by rewriting the URL to connect to the forwarded local port, and passing all curl options that were given on the command line.

Installation

If $GOPATH/bin is in the PATH, the plugin can be installed with:

$ go install github.com/segmentio/kubectl-curl@latest

If it was installed properly, it will be visibile when listing kubectl plugins:

$ kubectl plugin list
The following compatible plugins are available:

/.../kubectl-curl

Usage

kubectl curl [options] URL [container]

• In the URL, the host part must be the name of the pod to send the request to.
• If no port number is specified, the request will be sent to a http port.
• If there are multiple containers with a http port, the name of the container to send to the request to must be specified after the URL.

Examples

This section records common use cases for this kubectl plugin.

Collecting profiles of Go programs

$ kubectl curl "http://{pod}/debug/pprof/profile?debug=1&seconds=10" > ./profile
$ go tool pprof -http :6060 ./profile

• Full documentation: net/http/pprof

Retrieving prometheus metrics

$ kubectl curl http://{pod}/metrics
...

kubectl-curl's Issues

Allow curl-ing to services in addition to pods

I would like to be able to do this:
$ kubectl curl http://{svc-name}/metrics

Unable to use the --user option

When I try to use the --user username:password option, I consistently get this error message:

• ERROR: auth info "username:password" does not exist
  Error: exit status 1

Any chance this repo is still being watched?

Cannot use -X argument

While trying to use -X POST, the plugin complains such argument is invalid (set URL and CONTAINER to some valid values). I have seen a similar behavior while using -d.

$ kubectl curl -i -X POST $URL $CONTAINER
curl: option --request=POST: is unknown
curl: try 'curl --help' or 'curl --manual' for more information

Reproduced in both macOS and Ubuntu 20.04. Details below.

MacOS environment:

$ curl --version
curl 7.77.0 (x86_64-apple-darwin21.0) libcurl/7.77.0 (SecureTransport) LibreSSL/2.8.3 zlib/1.2.11 nghttp2/1.42.0
Release-Date: 2021-05-26
Protocols: dict file ftp ftps gopher gophers http https imap imaps ldap ldaps mqtt pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS GSS-API HSTS HTTP2 HTTPS-proxy IPv6 Kerberos Largefile libz MultiSSL NTLM NTLM_WB SPNEGO SSL UnixSockets

$ kubectl version --client
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.2", GitCommit:"f5743093fd1c663cb0cbc89748f730662345d44d", GitTreeState:"clean", BuildDate:"2020-09-16T21:51:49Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"darwin/amd64"}

$ sw_vers
ProductName:	macOS
ProductVersion:	12.0.1
BuildVersion:	21A559

Linux environment:

$ curl --version
curl 7.68.0 (x86_64-pc-linux-gnu) libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3
Release-Date: 2020-01-08
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: AsynchDNS brotli GSS-API HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP UnixSockets

$ kubectl version --client
Client Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.1", GitCommit:"86ec240af8cbd1b60bcc4c03c20da9b98005b92e", GitTreeState:"clean", BuildDate:"2021-12-16T11:41:01Z", GoVersion:"go1.17.5", Compiler:"gc", Platform:"linux/amd64"}

$ lsb_release -a
LSB Version:	core-11.1.0ubuntu2-noarch:security-11.1.0ubuntu2-noarch
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal

Distribute kubectl plugin via Krew

Would it be possible to distribute this plugin via Krew? I believe this would help with the discovery of this plugin & simplifying the installation process 🙂

BUG: invalid character "{" in host name

I installed kubectl-curl from the README and ran into an error.

Install:

$ go install github.com/segmentio/kubectl-curl@latest 
go: downloading github.com/segmentio/kubectl-curl v0.1.5

Error:

$ kubectl curl http://{pod}/metrics
* ERROR: malformed URL: parse "http://{pod}/metrics": invalid character "{" in host name

using with go-teleport fails on first char missing

Hi! We use go-teleport installed at say tele.host.com. Using kubectl curl I get this:

m ~/D/  kubectl curl -vvv --debug "http://{podname}:3000/healthz"
* 2022/05/15 21:46:39 kubectl get -n default pod/{podname}
* 2022/05/15 21:46:41 forwarding local port 14187 to port 3000 of
* 2022/05/15 21:46:41 waiting for port fowarding to be established
* 2022/05/15 21:46:41 error upgrading connection: error sending request: Post "https://ele.host.com:3026/api/v1/namespaces/default/pods/zenith-console-7c64d658bd-mqvdv/portforward": dial tcp: lookup ele.host.com: no such host
^C* 2022/05/15 21:47:00 shutting down port forwarder
* 2022/05/15 21:47:00 waiting for port forwarder to stop

and it hangs forever. There is obviously no ele.host.com. Cause it's tele.host.com. Can't say for sure, this is not a go-teleport bug, sorry.

cannot load io/fs: malformed module path "io/fs": missing dot in first path element

ubuntu 20.04
go version go1.13.8 linux/amd64

go get github.com/segmentio/kubectl-curl@latest
build github.com/segmentio/kubectl-curl: cannot load io/fs: malformed module path "io/fs": missing dot in first path element