hugo/tpl/tplimpl/embedded/templates/opengraph.html

<meta property="og:title" content="{{ .Title }}" />
<meta property="og:description" content="{{ with .Description }}{{ . }}{{ else }}{{if .IsPage}}{{ .Summary }}{{ else }}{{ with .Site.Params.description }}{{ . }}{{ end }}{{ end }}{{ end }}" />
<meta property="og:type" content="{{ if .IsPage }}article{{ else }}website{{ end }}" />
<meta property="og:url" content="{{ .Permalink }}" />

{{- with $.Params.images -}}
{{- range first 6 . }}<meta property="og:image" content="{{ . | absURL }}" />{{ end -}}
{{- else -}}
{{- $images := $.Resources.ByType "image" -}}
{{- $featured := $images.GetMatch "*feature*" -}}
{{- if not $featured }}{{ $featured = $images.GetMatch "{*cover*,*thumbnail*}" }}{{ end -}}
{{- with $featured -}}
<meta property="og:image" content="{{ $featured.Permalink }}"/>
{{- else -}}
{{- with $.Site.Params.images }}<meta property="og:image" content="{{ index . 0 | absURL }}"/>{{ end -}}
{{- end -}}
{{- end -}}

{{- if .IsPage }}
{{- $iso8601 := "2006-01-02T15:04:05-07:00" -}}
<meta property="article:section" content="{{ .Section }}" />
{{ with .PublishDate }}<meta property="article:published_time" {{ .Format $iso8601 | printf "content=%q" | safeHTMLAttr }} />{{ end }}
{{ with .Lastmod }}<meta property="article:modified_time" {{ .Format $iso8601 | printf "content=%q" | safeHTMLAttr }} />{{ end }}
{{- end -}}

{{- with .Params.audio }}<meta property="og:audio" content="{{ . }}" />{{ end }}
{{- with .Params.locale }}<meta property="og:locale" content="{{ . }}" />{{ end }}
{{- with .Site.Params.title }}<meta property="og:site_name" content="{{ . }}" />{{ end }}
{{- with .Params.videos }}{{- range . }}
<meta property="og:video" content="{{ . | absURL }}" />
{{ end }}{{ end }}

{{- /* If it is part of a series, link to related articles */}}
{{- $permalink := .Permalink }}
{{- $siteSeries := .Site.Taxonomies.series }}
{{ with .Params.series }}{{- range $name := . }}
  {{- $series := index $siteSeries ($name | urlize) }}
  {{- range $page := first 6 $series.Pages }}
    {{- if ne $page.Permalink $permalink }}<meta property="og:see_also" content="{{ $page.Permalink }}" />{{ end }}
  {{- end }}
{{ end }}{{ end }}

{{- /* Facebook Page Admin ID for Domain Insights */}}
{{- with .Site.Social.facebook_admin }}<meta property="fb:admins" content="{{ . }}" />{{ end }}