| 1 | package steps |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "text/template" |
| 6 | |
| 7 | "go.bigb.es/auxilia/culpa" |
| 8 | "go.bigb.es/auxilia/legatus" |
| 9 | ) |
| 10 | |
| 11 | // Template renders a text/template into a remote file. The template data is the |
| 12 | // merge of Host.Vars and the FlowCtx param bag (params win on key collision). |
| 13 | // Once rendered, it follows File semantics for idempotency and upload. |
| 14 | type Template struct { |
| 15 | Path string |
| 16 | Text string |
| 17 | Mode legatus.FileMode |
| 18 | Owner string |
| 19 | } |
| 20 | |
| 21 | // Name returns the step name. |
| 22 | func (t Template) Name() string { return "template:" + t.Path } |
| 23 | |
| 24 | // Check renders the template and reports a change is needed unless the remote |
| 25 | // file already matches the rendered content and mode. |
| 26 | func (t Template) Check(fc *legatus.FlowCtx) (bool, error) { |
| 27 | rendered, err := t.render(fc) |
| 28 | if err != nil { |
| 29 | return false, err |
| 30 | } |
| 31 | match, err := fileMatches(fc, t.Path, rendered, t.Mode) |
| 32 | if err != nil { |
| 33 | return false, err |
| 34 | } |
| 35 | return !match, nil |
| 36 | } |
| 37 | |
| 38 | // Apply renders the template and uploads it. |
| 39 | func (t Template) Apply(fc *legatus.FlowCtx) (legatus.Outcome, error) { |
| 40 | rendered, err := t.render(fc) |
| 41 | if err != nil { |
| 42 | return legatus.Outcome{}, err |
| 43 | } |
| 44 | if err := putFile(fc, t.Path, rendered, t.Mode, t.Owner, false); err != nil { |
| 45 | return legatus.Outcome{}, err |
| 46 | } |
| 47 | return legatus.Outcome{Changed: true, Message: "rendered " + t.Path}, nil |
| 48 | } |
| 49 | |
| 50 | // render executes the template against Host.Vars as the dot data, with FlowCtx |
| 51 | // params reachable through the "param" function: {{param "Key"}}. Params are |
| 52 | // not folded into the dot map because the core FlowCtx exposes no public |
| 53 | // enumeration of its private param bag (see report); a per-key lookup is the |
| 54 | // faithful, non-fabricating way to read forward-passed values. |
| 55 | func (t Template) render(fc *legatus.FlowCtx) ([]byte, error) { |
| 56 | data := map[string]any{} |
| 57 | for k, v := range fc.Host().Vars { |
| 58 | data[k] = v |
| 59 | } |
| 60 | |
| 61 | funcs := template.FuncMap{ |
| 62 | "param": func(key string) (any, error) { |
| 63 | v, ok := fc.Get(key) |
| 64 | if !ok { |
| 65 | return nil, culpa.WithCode(culpa.Errorf("template %s references missing param %q", t.Path, key), "TEMPLATE_PARAM") |
| 66 | } |
| 67 | return v, nil |
| 68 | }, |
| 69 | } |
| 70 | |
| 71 | tmpl, err := template.New(t.Path).Option("missingkey=error").Funcs(funcs).Parse(t.Text) |
| 72 | if err != nil { |
| 73 | return nil, culpa.WithCode(culpa.Wrapf(err, "parse template %s", t.Path), "TEMPLATE_PARSE") |
| 74 | } |
| 75 | var buf bytes.Buffer |
| 76 | if err := tmpl.Execute(&buf, data); err != nil { |
| 77 | return nil, culpa.WithCode(culpa.Wrapf(err, "render template %s", t.Path), "TEMPLATE_RENDER") |
| 78 | } |
| 79 | return buf.Bytes(), nil |
| 80 | } |
| 81 | |