Make the chart work with a sqlite3 database (#124)

There are currently 2 issues that prevent using this chart to deploy gitea with a SQLite3 database.

1) The value from *gitea.config.database.HOST* is used to set *db.servicename* when  all the databases under *gitea.database.buildIn* are not enabled. This causes a type error during the template processing:
`Error: UPGRADE FAILED: template: gitea/templates/gitea/init.yaml:24:20: executing "gitea/templates/gitea/init.yaml" at <include "db.servicename" .>: error calling include: template: gitea/templates/_helpers.tpl:64:31: executing "db.servicename" at <.Values.gitea.config.database.HOST>: wrong type for value; expected string; got interface {}`

2) In *init_gitea.sh*, we use the value *db.servicename* and *db.port* to ping the database. If this database responds to ping, we proceed with the init. The problem here is that *db.port* is not set when all the databases under *gitea.database.buildIn* are disabled. In turn, this raises an error from busybox's *nc*, because no parameter is passed for *PORT*. This causes the init container to go in *CrashLoopBackOff* forever.

The simple fix that is proposed in this PR is to check wether or not *.Values.gitea.config.database.DB_TYPE* is set to determine the value *db.servicename*. If *DB_TYPE* is *'sqlite3'*, leave *db.servicename* empty and use that to bypass the database ping.

Co-authored-by: Baptiste Covolato <b.covolato@gmail.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/124
Reviewed-by: Andrew Thornton <art27@cantab.net>
Reviewed-by: lafriks <lafriks@noreply.gitea.io>
Reviewed-by: luhahn <luhahn@noreply.gitea.io>
Co-authored-by: Nakrez <nakrez@noreply.gitea.io>
Co-committed-by: Nakrez <nakrez@noreply.gitea.io>

templates/_helpers.tpl

@@ -60,7 +60,7 @@ app.kubernetes.io/instance: {{ .Release.Name }}
 {{- printf "%s-mysql" .Release.Name -}}
 {{- else if .Values.gitea.database.builtIn.mariadb.enabled -}}
 {{- printf "%s-mariadb" .Release.Name -}}
-{{- else -}}
+{{- else if ne .Values.gitea.config.database.DB_TYPE "sqlite3" -}}
 {{- $parts := split ":" .Values.gitea.config.database.HOST -}}
 {{- printf "%s %s" $parts._0 $parts._1 -}}
 {{- end -}}

templates/gitea/init.yaml

@@ -21,7 +21,9 @@ stringData:
     mkdir -p /data/gitea/conf
     cp /etc/gitea/conf/app.ini /data/gitea/conf/app.ini
     chmod a+rwx /data/gitea/conf/app.ini
+    {{- if include "db.servicename" . }}
     nc -v -w2 -z {{ include "db.servicename" . }} {{ include "db.port" . }} && \
+    {{- end }}
     su git -c ' \
     set -x; \
     gitea migrate; \