docker: update start.sh and set container option to false by default

- Clean up of start.sh w/ addition of more comment
- Set socat option to false by default
- Added default value to SOCAT_LINK & RUN_CROND in the script to make it
  cleaner
- This commit contains non backward-compatible change: any configuration using socat links will either:
    - need to be updated to use DNS name when querrying external service
    - set environment variable SOCAT_LINK to true when launching the updated container

docker/README.md

@@ -86,7 +86,7 @@ This container have some options available via environment variables, these opti
       Bind linked docker container to localhost socket using socat.
       Any exported port from a linked container will be binded to the matching port on localhost.
   - <u>Disclaimer:</u>
-      As this option rely on the environment variable created by docker when a container is linked, this option should be deactivated in managed environment such as Rancher or Kubernetes (set to `0` or `false`)
+      As this option rely on the environment variable created by docker when a container is linked, this option should not be activated in managed environment such as Rancher or Kubernetes.
 - **RUN_CROND**:
   - <u>Possible value:</u>
       `true`, `false`, `1`, `0`

docker/start.sh

@@ -1,8 +1,31 @@
 #!/bin/sh
 
+## Container configuration
+SOCAT_LINK=${SOCAT_LINK:-false}
+RUN_CROND=${RUN_CROND:-false}
+
+## Container utils
+cleanup() {
+    # Cleanup SOCAT services and s6 event folder
+    # On start and on shutdown in case container has been killed
+    rm -rf $(find /app/gogs/docker/s6/ -name 'event')
+    rm -rf /app/gogs/docker/s6/SOCAT_*
+}
+
+create_volume_subfolder() {
+    # Create VOLUME subfolder
+    for f in /data/gogs/data /data/gogs/conf /data/gogs/log /data/git /data/ssh; do
+        if ! test -d $f; then
+            mkdir -p $f
+        fi
+    done
+}
+
+## Container option activators
 create_socat_links() {
     # Bind linked docker container to localhost socket using socat
     USED_PORT="3000:22"
+    echo "init:socat  | Socat links will be created (requested via SOCAT_LINK)" 1>&2
     while read NAME ADDR PORT; do
         if test -z "$NAME$ADDR$PORT"; then
             continue
@@ -22,42 +45,37 @@ create_socat_links() {
 EOT
 }
 
-cleanup() {
-    # Cleanup SOCAT services and s6 event folder
-    # On start and on shutdown in case container has been killed
-    rm -rf $(find /app/gogs/docker/s6/ -name 'event')
-    rm -rf /app/gogs/docker/s6/SOCAT_*
+activate_crond () {
+    # Request s6 to run crond
+    echo "init:crond  | Cron Daemon (crond) will be run as requested by s6" 1>&2
+    rm -f /app/gogs/docker/s6/crond/down
 }
 
-create_volume_subfolder() {
-    # Create VOLUME subfolder
-    for f in /data/gogs/data /data/gogs/conf /data/gogs/log /data/git /data/ssh; do
-        if ! test -d $f; then
-            mkdir -p $f
-        fi
-    done
+deactivate_crond () {
+    # Tell s6 not to run the crond service
+    touch /app/gogs/docker/s6/crond/down
+}
+
+## Environment variable parser
+parse_container_options () {
+    # Parse opt-in / opt-out container optionss based on environment variable
+    # SOCAT_LINK: bind linked containers to localhost via socat
+    case $(echo "$SOCAT_LINK" | tr '[:upper:]' '[:lower:]') in
+      true|1) create_socat_links;;
+    esac
+    # RUN_CROND: request crond to be run inside the container
+    case $(echo "$RUN_CROND" | tr '[:upper:]' '[:lower:]') in
+      true|1) activate_crond;;
+      *)      deactivate_crond;;
+    esac
 }
 
+## Main
 cleanup
 create_volume_subfolder
+parse_container_options
 
-LINK=$(echo "$SOCAT_LINK" | tr '[:upper:]' '[:lower:]')
-if [ "$LINK" = "false" -o "$LINK" = "0" ]; then
-    echo "init:socat  | Will not try to create socat links as requested" 1>&2
-else
-    create_socat_links
-fi
-
-CROND=$(echo "$RUN_CROND" | tr '[:upper:]' '[:lower:]')
-if [ "$CROND" = "true" -o "$CROND" = "1" ]; then
-    echo "init:crond  | Cron Daemon (crond) will be run as requested by s6" 1>&2
-    rm -f /app/gogs/docker/s6/crond/down
-else
-    # Tell s6 not to run the crond service
-    touch /app/gogs/docker/s6/crond/down
-fi
-
-# Exec CMD or S6 by default if nothing present
+## End of initialization: exec CMD or s6 by default
 if [ $# -gt 0 ];then
     exec "$@"
 else