docs: mkdocs cleanup and caught up with latest README changes

docs/misc/rcon.md → docs/commands.md

@@ -1,3 +1,7 @@
+---
+title: Sending commands
+---
+
 [RCON](http://wiki.vg/RCON) is enabled by default, so you can `exec` into the container to
 access the Minecraft server console:
 

docs/configuration/auto-rcon-commands.md

@@ -0,0 +1,71 @@
+
+# Auto-execute RCON commands
+
+RCON commands can be configured to execute when the server starts, a client connects, or a client disconnects.
+
+!!! note
+
+    When declaring several commands within a compose file environment variable, it's easiest to use YAML's `|-` [block style indicator](https://yaml-multiline.info/).
+
+**On Server Start:**
+
+``` yaml
+      RCON_CMDS_STARTUP:  |-
+        gamerule doFireTick false
+        pregen start 200
+```
+
+**On Client Connection:**
+
+``` yaml
+      RCON_CMDS_ON_CONNECT:  |-
+        team join New @a[team=]
+```
+
+**Note:**
+* On client connect we only know there was a connection, and not who connected. RCON commands will need to be used for that.
+
+**On Client Disconnect:**
+
+``` yaml
+      RCON_CMDS_ON_DISCONNECT:  |-
+        gamerule doFireTick true
+```
+
+**On First Client Connect**
+
+``` yaml
+      RCON_CMDS_FIRST_CONNECT: |-
+        pregen stop
+```
+
+**On Last Client Disconnect**
+
+``` yaml
+      RCON_CMDS_LAST_DISCONNECT: |-
+        kill @e[type=minecraft:boat]
+        pregen start 200
+
+```
+
+**Example of rules for new players**
+
+Uses team NEW and team OLD to track players on the server. So move player with no team to NEW, run a command, move them to team OLD.
+[Reference Article](https://www.minecraftforum.net/forums/minecraft-java-edition/redstone-discussion-and/2213523-detect-players-first-join)
+
+``` yaml
+      RCON_CMDS_STARTUP:  |-
+        /pregen start 200
+        /gamerule doFireTick false
+        /team add New
+        /team add Old
+      RCON_CMDS_ON_CONNECT: |-
+        /team join New @a[team=]
+        /give @a[team=New] birch_boat
+        /team join Old @a[team=New]
+      RCON_CMDS_FIRST_CONNECT: |-
+        /pregen stop
+      RCON_CMDS_LAST_DISCONNECT: |-
+        /kill @e[type=minecraft:boat]
+        /pregen start 200
+```

docs/configuration/interpolating.md

@@ -0,0 +1,142 @@
+---
+title: Modifying config files
+---
+
+## Replacing variables inside configs
+
+Sometimes you have mods or plugins that require configuration information that is only available at runtime.
+For example if you need to configure a plugin to connect to a database,
+you don't want to include this information in your Git repository or Docker image.
+Or maybe you have some runtime information like the server name that needs to be set
+in your config files after the container starts.
+
+For those cases there is the option to replace defined variables inside your configs
+with environment variables defined at container runtime.
+
+When the environment variable `REPLACE_ENV_IN_PLACE` is set to `true` (the default), the startup script will go through all files inside the container's `/data` path and replace variables that match the container's environment variables. Variables can instead (or in addition to) be replaced in files sync'ed from `/plugins`, `/mods`, and `/config` by setting `REPLACE_ENV_DURING_SYNC` to `true` (defaults to `false`).
+
+Variables that you want to replace need to be declared inside curly brackets and prefixed with a dollar sign, such as  `${CFG_YOUR_VARIABLE}`, which is same as many scripting languages.
+
+You can also change `REPLACE_ENV_VARIABLE_PREFIX`, which defaults to "CFG_", to limit which environment variables are allowed to be used. For example, with "CFG_" as the prefix, the variable `${CFG_DB_HOST}` would be subsituted, but not `${DB_HOST}`.
+
+If you want to use a file's content for value, such as when using secrets mounted as files, declare the placeholder named like normal in the file and declare an environment variable named the same but with the suffix `_FILE`.
+
+For example, a `my.cnf` file could contain:
+
+```
+[client]
+password = ${CFG_DB_PASSWORD}
+```
+
+...a secret declared in the compose file with:
+```yaml
+secrets:
+  db_password:
+    external: true
+```
+
+...and finally the environment variable would be named with a `_FILE` suffix and point to the mounted secret:
+```yaml
+    environment:
+      CFG_DB_PASSWORD_FILE: /run/secrets/db_password
+```
+
+Variables will be replaced in files with the following extensions:
+`.yml`, `.yaml`, `.txt`, `.cfg`, `.conf`, `.properties`.
+
+Specific files can be excluded by listing their name (without path) in the variable `REPLACE_ENV_VARIABLES_EXCLUDES`.
+
+Paths can be excluded by listing them in the variable `REPLACE_ENV_VARIABLES_EXCLUDE_PATHS`. Path
+excludes are recursive. Here is an example:
+```
+REPLACE_ENV_VARIABLES_EXCLUDE_PATHS="/data/plugins/Essentials/userdata /data/plugins/MyPlugin"
+```
+
+Here is a full example where we want to replace values inside a `database.yml`.
+
+```yml
+
+---
+database:
+  host: ${CFG_DB_HOST}
+  name: ${CFG_DB_NAME}
+  password: ${CFG_DB_PASSWORD}
+```
+
+This is how your `docker-compose.yml` file could look like:
+
+```yml
+version: "3.8"
+# Other docker-compose examples in /examples
+
+services:
+  minecraft:
+    image: itzg/minecraft-server
+    ports:
+      - "25565:25565"
+    volumes:
+      - "mc:/data"
+    environment:
+      EULA: "TRUE"
+      ENABLE_RCON: "true"
+      RCON_PASSWORD: "testing"
+      RCON_PORT: 28016
+      # enable env variable replacement
+      REPLACE_ENV_VARIABLES: "TRUE"
+      # define an optional prefix for your env variables you want to replace
+      ENV_VARIABLE_PREFIX: "CFG_"
+      # and here are the actual variables
+      CFG_DB_HOST: "http://localhost:3306"
+      CFG_DB_NAME: "minecraft"
+      CFG_DB_PASSWORD_FILE: "/run/secrets/db_password"
+
+volumes:
+  mc:
+  rcon:
+
+secrets:
+  db_password:
+    file: ./db_password
+```
+
+## Patching existing files
+
+JSON path based patches can be applied to one or more existing files by setting the variable `PATCH_DEFINITIONS` to the path of a directory that contains one or more [patch definition json files](https://github.com/itzg/mc-image-helper#patchdefinition) or a [patch set json file](https://github.com/itzg/mc-image-helper#patchset).
+
+Variable placeholders in the patch values can be restricted by setting `REPLACE_ENV_VARIABLE_PREFIX`, which defaults to "CFG_".
+
+The following example shows a patch-set file were various fields in the `paper.yaml` configuration file can be modified and added:
+
+```json
+{
+  "patches": [
+    {
+      "file": "/data/paper.yml",
+      "ops": [
+        {
+          "$set": {
+            "path": "$.verbose",
+            "value": true
+          }
+        },
+        {
+          "$set": {
+            "path": "$.settings['velocity-support'].enabled",
+            "value": "${CFG_VELOCITY_ENABLED}",
+            "value-type": "bool"
+          }
+        },
+        {
+          "$put": {
+            "path": "$.settings",
+            "key": "my-test-setting",
+            "value": "testing"
+          }
+        }
+      ]
+    }
+  ]
+}
+```
+
+> **NOTES:** Only JSON and Yaml files can be patched at this time. TOML support is planned to be added next. Removal of comments and other cosmetic changes will occur when patched files are processed.

docs/configuration/jvm-options.md

@@ -0,0 +1,77 @@
+# JVM Options
+
+## Memory Limit
+
+By default, the image declares an initial and maximum Java memory-heap limit of 1 GB. There are several ways to adjust the memory settings:
+
+- `MEMORY`: "1G" by default, can be used to adjust both initial (`Xms`) and max (`Xmx`) memory heap settings of the JVM
+- `INIT_MEMORY`: independently sets the initial heap size
+- `MAX_MEMORY`: independently sets the max heap size
+
+The values of all three are passed directly to the JVM and support format/units as `<size>[g|G|m|M|k|K]`. For example:
+
+    -e MEMORY=2G
+
+To let the JVM calculate the heap size from the container declared memory limit, unset `MEMORY` with an empty value, such as `-e MEMORY=""`. By default, the JVM will use 25% of the container memory limit as the heap limit; however, as an example the following would tell the JVM to use 75% of the container limit of 2GB of memory:
+
+     -e MEMORY="" -e JVM_XX_OPTS="-XX:MaxRAMPercentage=75" -m 2000M
+
+!!! important
+    The settings above only set the Java **heap** limits. Memory resource requests and limits on the overall container should also account for non-heap memory usage. An extra 25% is [a general best practice](https://dzone.com/articles/best-practices-java-memory-arguments-for-container).
+
+## Extra JVM Options
+
+General JVM options can be passed to the Minecraft Server invocation by passing a `JVM_OPTS`
+environment variable. The JVM requires `-XX` options to precede `-X` options, so those can be declared in `JVM_XX_OPTS`. Both variables are space-delimited, raw JVM arguments.
+
+```
+docker run ... -e JVM_OPTS="-someJVMOption someJVMOptionValue" ...
+```
+
+**NOTE** When declaring `JVM_OPTS` in a compose file's `environment` section with list syntax, **do not** include the quotes:
+
+```yaml
+    environment:
+      - EULA=true
+      - JVM_OPTS=-someJVMOption someJVMOptionValue 
+```
+
+Using object syntax is recommended and more intuitive:
+
+```yaml
+    environment:
+      EULA: "true"
+      JVM_OPTS: "-someJVMOption someJVMOptionValue"
+# or
+#     JVM_OPTS: -someJVMOption someJVMOptionValue
+```
+
+As a shorthand for passing several system properties as `-D` arguments, you can instead pass a comma separated list of `name=value` or `name:value` pairs with `JVM_DD_OPTS`. (The colon syntax is provided for management platforms like Plesk that don't allow `=` inside a value.)
+
+For example, instead of passing
+
+```yaml
+  JVM_OPTS: -Dfml.queryResult=confirm -Dname=value
+```
+
+you can use
+
+```yaml
+  JVM_DD_OPTS: fml.queryResult=confirm,name=value
+```
+
+## Enable Remote JMX for Profiling
+
+To enable remote JMX, such as for profiling with VisualVM or JMC, add the environment variable `ENABLE_JMX=true`, set `JMX_HOST` to the IP/host running the Docker container, and add a port forwarding of TCP port 7091, such as:
+
+```
+-e ENABLE_JMX=true -e JMX_HOST=$HOSTNAME -p 7091:7091
+```
+
+## Enable Aikar's Flags
+
+[Aikar has done some research](https://aikar.co/2018/07/02/tuning-the-jvm-g1gc-garbage-collector-flags-for-minecraft/) into finding the optimal JVM flags for GC tuning, which becomes more important as more users are connected concurrently. The set of flags documented there can be added using
+
+    -e USE_AIKAR_FLAGS=true
+
+When `MEMORY` is greater than or equal to 12G, then the Aikar flags will be adjusted according to the article.