examples for opm alpha render-graph to generate channel graph images (#1012)

* examples for  to generate channel graph images
* added details for how to avoid mermaid's maxTextSize limits
* fixing comment
* revised for the new render-graph command

Signed-off-by: Jordan Keister <[email protected]>
Upstream-commit: 7470c35da86316cbd44f663a45048c3d73edd3b6
Upstream-repository: operator-registry

Author: grokspawn

staging/operator-registry/cmd/opm/alpha/render-graph/cmd.go

@@ -22,6 +22,32 @@ func NewCmd() *cobra.Command {
 		Short: "Generate mermaid-formatted view of upgrade graph of operators in an index",
 		Long:  `Generate mermaid-formatted view of upgrade graphs of operators in an index`,
 		Args:  cobra.MinimumNArgs(1),
+		Example: `
+#
+# Output channel graph of a catalog in mermaid format
+#
+$ opm alpha render-graph quay.io/operatorhubio/catalog:latest
+
+#
+# Output channel graph of a catalog and generate a scaled vector graphic (SVG) representation
+# Note:  this pipeline filters out the comments about lacking skipRange support
+#
+$ opm alpha render-graph quay.io/operatorhubio/catalog:latest | \
+    grep -Ev '^<!--.*$' | \
+    docker run --rm -i -v "$PWD":/data ghcr.io/mermaid-js/mermaid-cli/mermaid-cli -o /data/operatorhubio-catalog.svg
+
+# Note:  mermaid has a default maxTextSize of 30 000 characters.  To override this, generate a JSON-formatted initialization file for
+# mermaid like this (using 300 000 for the limit):
+$ cat << EOF > ./mermaid.json
+{ "maxTextSize": 300000 }
+EOF
+# and then pass the file for initialization configuration, via the '-c' option, like:
+$ opm alpha render-graph quay.io/operatorhubio/catalog:latest | \
+    grep -Ev '^<!--.*$' | \
+    docker run --rm -i -v "$PWD":/data ghcr.io/mermaid-js/mermaid-cli/mermaid-cli -c /data/mermaid.json -o /data/operatorhubio-catalog.svg
+
+
+		`,
 		Run: func(cmd *cobra.Command, args []string) {
 			// The bundle loading impl is somewhat verbose, even on the happy path,
 			// so discard all logrus default logger logs. Any important failures will be