bryanpedini
9a85e9acc8
Lazy Docker Engine client on the local socket listing running containers with a per-call timeout; unit tests and e2e tests against a fake Engine socket and real containers.
71 lines
2.1 KiB
Go
71 lines
2.1 KiB
Go
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright (C) 2026 Bryan Joshua Pedini
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package main
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import (
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"context"
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"fmt"
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"log/slog"
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"time"
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"github.com/moby/moby/api/types/container"
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"github.com/moby/moby/client"
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)
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// dockerHost is the Docker Engine endpoint used in production
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const dockerHost = "unix:///var/run/docker.sock"
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// dockerListTimeout bounds every container-list call (the SDK has no default timeout)
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const dockerListTimeout = 10 * time.Second
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// ContainerLister is the narrow Docker dependency of the HTTP layer
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type ContainerLister interface {
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ListRunningContainers(ctx context.Context) ([]container.Summary, error)
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}
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// DockerClient wraps the Docker Engine SDK client
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type DockerClient struct {
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cli *client.Client
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log *slog.Logger
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timeout time.Duration
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}
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// NewDockerClient creates a client for the given Engine host (e.g. unix:///var/run/docker.sock)
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// The connection is lazy: an absent or inaccessible socket only fails individual requests
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func NewDockerClient(host string, log *slog.Logger) (*DockerClient, error) {
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cli, err := client.New(client.WithHost(host))
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if err != nil {
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return nil, fmt.Errorf("create docker client: %w", err)
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}
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return &DockerClient{cli: cli, log: log, timeout: dockerListTimeout}, nil
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}
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// ListRunningContainers returns the running containers, like `docker ps`
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// The result is never nil, so it serializes as [] when empty
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func (d *DockerClient) ListRunningContainers(ctx context.Context) ([]container.Summary, error) {
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defer traceFunc(ctx, d.log, "DockerClient.ListRunningContainers")()
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ctx, cancel := context.WithTimeout(ctx, d.timeout)
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defer cancel()
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// All=false: running containers only
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res, err := d.cli.ContainerList(ctx, client.ContainerListOptions{})
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if err != nil {
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return nil, fmt.Errorf("list containers: %w", err)
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}
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items := res.Items
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if items == nil {
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items = []container.Summary{}
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}
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for _, c := range items {
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trace(ctx, d.log, "container listed", "id", c.ID, "names", c.Names, "image", c.Image, "state", c.State)
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}
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return items, nil
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}
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// Close releases the client's resources
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func (d *DockerClient) Close() error {
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return d.cli.Close()
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}
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