Add --format to docker-search

Signed-off-by: Jeremy Chambers <jeremy@thehipbot.com>
Signed-off-by: Boaz Shuster <ripcurld.github@gmail.com>

docs/reference/commandline/search.md

@@ -25,6 +25,7 @@ Options:
                        - is-automated=(true|false)
                        - is-official=(true|false)
                        - stars=<number> - image has at least 'number' stars
+      --format string  Pretty-print images using a Go template
       --help           Print usage
       --limit int      Max number of search results (default 25)
       --no-trunc       Don't truncate output
@@ -144,3 +145,58 @@ NAME                 DESCRIPTION                                     STARS     O
 progrium/busybox                                                     50                   [OK]
 radial/busyboxplus   Full-chain, Internet enabled, busybox made...   8                    [OK]
 ```
+
+### Format the output
+
+The formatting option (`--format`) pretty-prints search output
+using a Go template.
+
+Valid placeholders for the Go template are:
+
+| Placeholder    | Description                       |
+| -------------- | --------------------------------- |
+| `.Name`        | Image Name                        |
+| `.Description` | Image description                 |
+| `.StarCount`   | Number of stars for the image     |
+| `.IsOfficial`  | "OK" if image is official         |
+| `.IsAutomated` | "OK" if image build was automated |
+
+When you use the `--format` option, the `search` command will
+output the data exactly as the template declares. If you use the
+`table` directive, column headers are included as well.
+
+The following example uses a template without headers and outputs the
+`Name` and `StarCount` entries separated by a colon for all images:
+
+```bash
+{% raw %}
+$ docker search --format "{{.Name}}: {{.StarCount}}" nginx
+
+nginx: 5441
+jwilder/nginx-proxy: 953
+richarvey/nginx-php-fpm: 353
+million12/nginx-php: 75
+webdevops/php-nginx: 70
+h3nrik/nginx-ldap: 35
+bitnami/nginx: 23
+evild/alpine-nginx: 14
+million12/nginx: 9
+maxexcloo/nginx: 7
+{% endraw %}
+```
+
+This example outputs a table format:
+
+```bash
+{% raw %}
+$ docker search --format "table {{.Name}}\t{{.IsAutomated}}\t{{.IsOfficial}}" nginx
+
+NAME                                     AUTOMATED           OFFICIAL
+nginx                                                        [OK]
+jwilder/nginx-proxy                      [OK]                
+richarvey/nginx-php-fpm                  [OK]                
+jrcs/letsencrypt-nginx-proxy-companion   [OK]                
+million12/nginx-php                      [OK]                
+webdevops/php-nginx                      [OK]                
+{% endraw %}
+```