Tool to quickly select and view Kubernetes container logs using fzf (screenshot below in comments)

kubelog.py

#!/usr/bin/env python3
"""
kubelog is a tool that lists all pods and their contains using fzf
and prints the logs for the selected one.

Options to get fzf:
- https://github.com/junegunn/fzf
- brew install fzf
"""

import os
import sys
import json
import argparse
import shlex
import shutil
from subprocess import Popen, PIPE, STDOUT

parser = argparse.ArgumentParser(usage=__doc__)
parser.add_argument("--list", "-l", action="store_true", help="List and exit")
parser.add_argument("--namespace", "-n", help="Specific namespace")
parser.add_argument("--preview", help=argparse.SUPPRESS)


def run():
    # Unknown args are passed to kubectl logs
    opt, other = parser.parse_known_args()

    width, height = shutil.get_terminal_size()
    preview_height = height // 2

    # Hidden preview option, called by fzf
    if opt.preview:
        namespace, name, container, *rest = opt.preview.split()
        os.execlp("kubectl", "kubectl", "logs", "-n", namespace, name,
                  "-c", container, "--tail={}".format(preview_height))
        return # never reached

    # Get JSON with all pod info
    # FIXME: use subprocess, UNSAFE
    if opt.namespace:
        qn = shlex.quote(opt.namespace)
        get_cmd = "kubectl get -n {} pod -o json".format(qn)
    else:
        get_cmd = "kubectl get --all-namespaces pod -o json"
    pods_data = os.popen(get_cmd, "r").read()
    pods = json.loads(pods_data)

    # Find all container info
    containers = []
    def add_container(namespace, name, container, st):
        state = list(st.keys())[0]
        started = st[state].get('startedAt')
        containers.append("{:20s} {:60s} {:30s} ({} {})".format(
                namespace, name, container, state, started))

    for pod in pods['items']:
        m = pod['metadata']
        for ck in ('containerStatuses', 'initContainerStatuses'):
            for c in pod.get('status', {}).get(ck, []):
                add_container(m['namespace'], m['name'], c['name'], c['state'])

    containers.sort()

    # For --list, list containers and exit (same if output is not a tty)
    if opt.list or not sys.stdout.isatty():
        for line in containers:
            print(line)
        return

    # Show fzf to select a container, calling self for --preview
    # This keeps a '{}' placeholder for fzf
    preview_cmd = "{} --preview={{}}".format(shlex.quote(sys.argv[0]))
    fzf_cmd = [
        'fzf',
        "--preview=" + preview_cmd,
        '--preview-window=up:{}'.format(preview_height),
    ]
    p = Popen(fzf_cmd, stdin=PIPE, stdout=PIPE)
    stdin_bytes = '\n'.join(containers).encode('ascii')
    selection = p.communicate(input=stdin_bytes)[0].decode('ascii')
    if not selection:
        print("No container selected")
        sys.exit(1)

    # Show logs for selected container
    namespace, name, container, *rest = selection.split()
    cmd = ["kubectl", "logs", "-n", namespace, name, "-c", container, *other]
    print("=" * width)
    cmd_str = ' '.join( shlex.quote(x) for x in cmd )
    print("=== {}".format(cmd_str))
    print("=" * width)
    os.execlp(cmd[0], *cmd)

    
if __name__ == '__main__':
    run()

Don't forget to make it executable (chmod a+x kubelog), or the preview function won't work.