|
| 1 | +package mcp |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "errors" |
| 6 | + "fmt" |
| 7 | + "log/slog" |
| 8 | + "os" |
| 9 | + "strings" |
| 10 | + "sync" |
| 11 | + |
| 12 | + "github.com/docker/cagent/pkg/environment" |
| 13 | + "github.com/docker/cagent/pkg/gateway" |
| 14 | + "github.com/docker/cagent/pkg/tools" |
| 15 | + "gopkg.in/yaml.v3" |
| 16 | +) |
| 17 | + |
| 18 | +type GatewayToolset struct { |
| 19 | + ref string |
| 20 | + config any |
| 21 | + toolFilter []string |
| 22 | + envProvider environment.Provider |
| 23 | + |
| 24 | + once sync.Once |
| 25 | + initErr error |
| 26 | + cmdToolset *Toolset |
| 27 | + cleanUpConfig func() error |
| 28 | + cleanUpSecrets func() error |
| 29 | +} |
| 30 | + |
| 31 | +var _ tools.ToolSet = (*GatewayToolset)(nil) |
| 32 | + |
| 33 | +func NewGatewayToolset(ref string, config any, toolFilter []string, envProvider environment.Provider) *GatewayToolset { |
| 34 | + slog.Debug("Creating MCP Gateway toolset", "ref", ref, "toolFilter", toolFilter) |
| 35 | + |
| 36 | + return &GatewayToolset{ |
| 37 | + ref: ref, |
| 38 | + config: config, |
| 39 | + toolFilter: toolFilter, |
| 40 | + envProvider: envProvider, |
| 41 | + cleanUpConfig: func() error { return nil }, |
| 42 | + cleanUpSecrets: func() error { return nil }, |
| 43 | + } |
| 44 | +} |
| 45 | + |
| 46 | +func (t *GatewayToolset) Instructions() string { |
| 47 | + return "" |
| 48 | +} |
| 49 | + |
| 50 | +func (t *GatewayToolset) configureOnce(ctx context.Context) error { |
| 51 | + mcpServerName := parseServerRef(t.ref) |
| 52 | + |
| 53 | + // Check which secrets (env vars) are required by the MCP server. |
| 54 | + secrets, err := gateway.RequiredEnvVars(ctx, mcpServerName, gateway.DockerCatalogURL) |
| 55 | + if err != nil { |
| 56 | + return fmt.Errorf("reading which secrets the MCP server needs: %w", err) |
| 57 | + } |
| 58 | + |
| 59 | + // Make sure all the required secrets are available in the environment. |
| 60 | + // TODO(dga): Ideally, the MCP gateway would use the same provider that we have. |
| 61 | + fileSecrets, err := writeSecretsToFile(ctx, mcpServerName, secrets, t.envProvider) |
| 62 | + if err != nil { |
| 63 | + return fmt.Errorf("writing secrets to file: %w", err) |
| 64 | + } |
| 65 | + t.cleanUpSecrets = func() error { return os.Remove(fileSecrets) } |
| 66 | + |
| 67 | + fileConfig, err := writeConfigToFile(ctx, mcpServerName, t.config) |
| 68 | + if err != nil { |
| 69 | + return fmt.Errorf("writing config to file: %w", err) |
| 70 | + } |
| 71 | + t.cleanUpConfig = func() error { return os.Remove(fileConfig) } |
| 72 | + |
| 73 | + // Isolate ourselves from the MCP Toolkit config by always using the Docker MCP catalog and custom config and secrets. |
| 74 | + // This improves shareability of agents. |
| 75 | + args := []string{ |
| 76 | + "mcp", "gateway", "run", |
| 77 | + "--servers", mcpServerName, |
| 78 | + "--catalog", gateway.DockerCatalogURL, |
| 79 | + "--secrets", fileSecrets, |
| 80 | + "--config", fileConfig, |
| 81 | + } |
| 82 | + t.cmdToolset = NewToolsetCommand("docker", args, nil, t.toolFilter) |
| 83 | + |
| 84 | + return nil |
| 85 | +} |
| 86 | + |
| 87 | +func (t *GatewayToolset) ensureConfigured(ctx context.Context) error { |
| 88 | + t.once.Do(func() { |
| 89 | + t.initErr = t.configureOnce(ctx) |
| 90 | + }) |
| 91 | + return t.initErr |
| 92 | +} |
| 93 | + |
| 94 | +func (t *GatewayToolset) Tools(ctx context.Context) ([]tools.Tool, error) { |
| 95 | + if err := t.ensureConfigured(ctx); err != nil { |
| 96 | + return nil, err |
| 97 | + } |
| 98 | + return t.cmdToolset.Tools(ctx) |
| 99 | +} |
| 100 | + |
| 101 | +func (t *GatewayToolset) Start(ctx context.Context) error { |
| 102 | + if err := t.ensureConfigured(ctx); err != nil { |
| 103 | + return err |
| 104 | + } |
| 105 | + return t.cmdToolset.Start(ctx) |
| 106 | +} |
| 107 | + |
| 108 | +func (t *GatewayToolset) Stop() error { |
| 109 | + stopErr := t.cmdToolset.Stop() |
| 110 | + cleanUpSecretsErr := t.cleanUpSecrets() |
| 111 | + cleanUpConfigErr := t.cleanUpConfig() |
| 112 | + |
| 113 | + return errors.Join(stopErr, cleanUpSecretsErr, cleanUpConfigErr) |
| 114 | +} |
| 115 | + |
| 116 | +func parseServerRef(ref string) string { |
| 117 | + return strings.TrimPrefix(ref, "docker:") |
| 118 | +} |
| 119 | + |
| 120 | +func writeSecretsToFile(ctx context.Context, mcpServerName string, secrets []gateway.Secret, envProvider environment.Provider) (string, error) { |
| 121 | + var secretValues []string |
| 122 | + for _, secret := range secrets { |
| 123 | + v := envProvider.Get(ctx, secret.Env) |
| 124 | + if v == "" { |
| 125 | + // TODO(dga): Add a link to some doc that explains the different ways to provide secrets. |
| 126 | + return "", fmt.Errorf("MCP server %q requires environment variable %q to be set. Either set it before running cagent or run cagent with --env-from-file", mcpServerName, secret.Env) |
| 127 | + } |
| 128 | + |
| 129 | + secretValues = append(secretValues, fmt.Sprintf("%s=%s", secret.Name, v)) |
| 130 | + } |
| 131 | + |
| 132 | + // We have all the secrets, let's create a file with all of them for the MCP Gateway |
| 133 | + return writeTempFile("mcp-secrets-*", []byte(strings.Join(secretValues, "\n"))) |
| 134 | +} |
| 135 | + |
| 136 | +func writeConfigToFile(_ context.Context, mcpServerName string, config any) (string, error) { |
| 137 | + buf, err := yaml.Marshal(map[string]any{ |
| 138 | + mcpServerName: config, |
| 139 | + }) |
| 140 | + if err != nil { |
| 141 | + return "", err |
| 142 | + } |
| 143 | + |
| 144 | + return writeTempFile("mcp-config-*", buf) |
| 145 | +} |
| 146 | + |
| 147 | +func writeTempFile(nameTemplate string, content []byte) (string, error) { |
| 148 | + f, err := os.CreateTemp("", nameTemplate) |
| 149 | + if err != nil { |
| 150 | + return "", fmt.Errorf("creating temp file: %w", err) |
| 151 | + } |
| 152 | + defer f.Close() |
| 153 | + |
| 154 | + if _, err := f.Write(content); err != nil { |
| 155 | + return "", err |
| 156 | + } |
| 157 | + |
| 158 | + return f.Name(), nil |
| 159 | +} |
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