diff --git a/.env.sample b/.env.sample
index 461c30b..cd08135 100644
--- a/.env.sample
+++ b/.env.sample
@@ -41,3 +41,5 @@ COMPOSE_FILE="compose.yml"
 # CMD_DEFAULT_PERMISSION=editable
 # CMD_EMAIL=true
 # CMD_SESSION_LIFE=1209600000
+# Only present in config.json (no equivalent env var):
+# DOCUMENT_MAX_LENGTH=100000
diff --git a/README.md b/README.md
index f1e7383..b97e7b5 100644
--- a/README.md
+++ b/README.md
@@ -28,8 +28,7 @@
 	abra app YOURAPPDOMAIN run app bash
 	. /docker-entrypoint2.sh -e
 	bin/manage_users
-	```
 
-[hedegedoc]: https://github.com/hackmdio/hedegedoc
+[hedegedoc]: https://github.com/hedgedoc/hedgedoc
 [abra]: https://git.autonomic.zone/autonomic-cooperative/abra
-[compose-traefik]: https://git.autonomic.zone/coop-cloud/traefik
+[compose-traefik]: https://git.autonomic.zone/coop-cloud/traefik
\ No newline at end of file
diff --git a/abra.sh b/abra.sh
index 413e4e8..9f9dbad 100644
--- a/abra.sh
+++ b/abra.sh
@@ -1,4 +1,4 @@
-export ENTRYPOINT_CONF_VERSION=v5
+export ENTRYPOINT_CONF_VERSION=v6
 
 abra_backup_app() {
   _abra_backup_dir "app:/home/hackmd/app/public/uploads/"
diff --git a/compose.yml b/compose.yml
index 7ca478f..cbc2360 100644
--- a/compose.yml
+++ b/compose.yml
@@ -26,6 +26,7 @@ services:
       - CMD_DEFAULT_PERMISSION
       - CMD_EMAIL
       - CMD_SESSION_LIFE
+      - DOCUMENT_MAX_LENGTH
     depends_on:
       - db
     networks:
@@ -40,6 +41,9 @@ services:
       - source: entrypoint_conf
         target: /docker-entrypoint.sh
         mode: 0555
+      - source: config_json
+        target: /files/config.json
+        mode: 0555
     deploy:
       restart_policy:
         condition: on-failure
@@ -90,6 +94,10 @@ networks:
     external: true
   internal:
 configs:
+  config_json:
+    name: ${STACK_NAME}_config_${ENTRYPOINT_CONF_VERSION}
+    file: config.json.tmpl
+    template_driver: golang
   entrypoint_conf:
     name: ${STACK_NAME}_entrypoint_${ENTRYPOINT_CONF_VERSION}
     file: entrypoint.sh.tmpl
diff --git a/config.json.tmpl b/config.json.tmpl
new file mode 100644
index 0000000..62a3dbd
--- /dev/null
+++ b/config.json.tmpl
@@ -0,0 +1,7 @@
+{
+  {{ if (env "DOCUMENT_MAX_LENGTH") }}
+  "production": {
+    "documentMaxLength": {{ env "DOCUMENT_MAX_LENGTH" }}
+    }
+  {{ end }}
+}