Add Docker build configuration for server

The final image is around 150M in size, which is totally reasonable.
Most of the size is added by the maps.

.dockerignore

@@ -0,0 +1,16 @@
+# remember: the last(!) line that matches a specific file defines the behavior
+
+# ignore everything, then unblock one by one (note: . does not work "for historical reasons")
+*
+
+#!.git/
+!README.md
+!CMakeLists.txt
+!config/
+!data/
+!doc/
+!docker/
+!src/
+
+# ignore the Dockerfile so changes in it don't retrigger an entire build
+!docker/Dockerfile

.gitignore

@@ -32,6 +32,7 @@ out
 *.core
 *.diff
 *.patch
+!docker/serverip.patch
 *.out
 home/
 cache/
@@ -54,3 +55,4 @@ GTAGS
 GRTAGS
 .idea/
 *build*/
+*.*swp*

docker/Dockerfile

@@ -0,0 +1,68 @@
+# first, let's build the software
+# this is going to take the most time
+FROM alpine:3.17 AS builder
+
+RUN apk add gcc g++ binutils sdl2-dev zlib-dev perl git wget ca-certificates coreutils mesa-dev musl-dev glu-dev \
+    sdl2_image-dev sdl2_mixer-dev psmisc cmake ninja
+
+RUN mkdir /blue-nebula
+WORKDIR /blue-nebula
+
+COPY src/ /blue-nebula/src
+COPY config/ /blue-nebula/config
+COPY data/ /blue-nebula/data
+
+COPY CMakeLists.txt /blue-nebula/
+COPY README.md /blue-nebula/
+COPY docker/serverip.patch /serverip.patch
+
+RUN git apply < /serverip.patch && \
+    ls -al && \
+    mkdir build && \
+    cd build && \
+    # TODO: server-only build configuration
+    cmake .. -DCMAKE_BUILD_TYPE=Release -G Ninja -DCMAKE_INSTALL_PREFIX=/blue-nebula/install && \
+    ninja -v && \
+    ninja install
+
+# next, we convert the example server config to a template
+# this is done in no time, so we do not have to benefit from Docker's caching a lot there
+FROM python:3.10-alpine AS template
+
+COPY docker/generate-servinit-template.py doc/examples/servinit.cfg /
+
+RUN python3 /generate-servinit-template.py /servinit.cfg > /servinit.tmpl
+
+
+
+# finally, let's build the final runtime image (doesn't need all of the build dependencies)
+FROM alpine:3.17
+
+MAINTAINER "TheAssassin <[email protected]>"
+
+RUN apk add tini && \
+    apk add --repository=https://dl-cdn.alpinelinux.org/alpine/edge/testing dockerize
+
+RUN adduser -S -D -h /blue-nebula blue-nebula
+WORKDIR /blue-nebula
+
+COPY --from=template /servinit.tmpl /
+COPY --from=builder /blue-nebula/install /blue-nebula/install
+
+# keep the directory read-only but allow writing to the file
+# this is needed since dockerize runs as blue-nebula and needs to modify the file
+# we might want to run dockerize separately and then run the process as blue-nebula
+RUN mkdir /blue-nebula/.blue-nebula && \
+    install -o blue-nebula -m 0644 /dev/null /blue-nebula/.blue-nebula/servinit.cfg
+
+# install runtime dependencies
+RUN apk add --no-cache libstdc++ libgcc
+
+# keep files copied from elsewhere read-only to prevent the process from writing files
+USER blue-nebula
+
+EXPOSE 28799/udp 28800/udp 28801/udp 28802/udp
+
+ENTRYPOINT ["/sbin/tini", "--"]
+
+CMD dockerize -template /servinit.tmpl:/blue-nebula/.blue-nebula/servinit.cfg install/bin/blue-nebula_server_linux

docker/docker-compose.yml.example

@@ -0,0 +1,25 @@
+version: "3"
+
+services:
+  bn-server:
+    image: ghcr.io/blue-nebula/server:latest
+    restart: unless-stopped
+
+    # adjust accordingly if you change the ports in the config
+    # note: the ports must be in sync! otherwise, the server will announce the wrong ports to the master
+    ports:
+      - "0.0.0.0:28801:28801/udp"
+      - "0.0.0.0:28802:28802/udp"
+
+    # most-if-not-all environment variables are exposed as upper-case environment variables as shown below
+    environment:
+      ADMIN_PASS: "so-secret"
+      SERVER_TYPE: 1
+      SERVER_PORT: 28801
+      SV_SERVERCLIENTS: 16
+      SV_SERVERDESC: "Example BN server running in Docker"
+      SV_SERVERMOTD: "Welcome to this example Blue Nebula server hosted in a Docker container!"
+
+    # to add additional maps, you can mount a directory as shown below
+    volumes:
+      - ./custom-maps:/blue-nebula/.blue-nebula/maps/

docker/generate-servinit-template.py

@@ -0,0 +1,164 @@
+#! /usr/bin/env python3
+
+import re
+import sys
+import textwrap
+
+
+class ParsingException(Exception):
+    pass
+
+
+def convert_variable(variable_name: str, default_value: str, comment: str, indentation: int = None):
+    if indentation is None:
+        indentation = 0
+
+    variable_name_upper = variable_name.upper()
+    env_var_name = ".Env.%s" % variable_name_upper
+
+    lines = []
+    lines.append("{{ if (contains .Env \"%s\") -}}" % variable_name_upper)
+    #lines.append(comment)
+    #lines.append("// default/example value: %s" % default_value)
+    lines.append("%s \"{{ %s }}\"" % (variable_name, env_var_name))
+    lines.append("{{ else -}}")
+    lines.append("// %s %s  %s" % (variable_name, default_value, comment))
+    lines.append("{{ end -}}")
+    lines.append("")
+
+    return textwrap.indent("\n".join(lines), " "*indentation)
+
+
+def parse_and_convert_variable(pattern: str, line: str, indentation: int = None):
+    match = re.match(pattern, line)
+
+    if not match:
+        return
+
+    return convert_variable(*match.groups(), indentation)
+
+
+def parse_regular_variable(line: str):
+    return parse_and_convert_variable(r"^//\s?((?:sv_|admin|server)\w+)\s+(.+)\s+(\/\/.*)$", line)
+
+
+def parse_rehashing_variable(line: str):
+    return parse_and_convert_variable(r"^    //\s*((?!irc)\w+)\s+(.+)\s+(\/\/.*)$", line, 4)
+
+
+def parse_add_variable(line: str):
+    match = re.match(r"^//\s? (add\w+)\s+(.+)\s*(|\/\/.*)$", line)
+
+    if not match:
+        return
+
+    variable_name, default_value, comment = match.groups()
+
+    variable_name_upper = variable_name.upper()
+    env_var_name = ".Env.%s" % variable_name_upper
+
+    lines = []
+    lines.append("{{ if (contains .Env \"%s\") -}}" % variable_name_upper)
+    #lines.append(comment)
+    #lines.append("// default/example value: %s" % default_value)
+    lines.append("{{ range $e := ( split %s \";\" ) -}}" % env_var_name)
+    lines.append("%s {{ $e }}" % variable_name)
+    lines.append("{{ end -}}")
+    lines.append("{{ else -}}")
+    lines.append(line)
+    lines.append("{{ end -}}")
+    lines.append("")
+
+    return "\n".join(lines)
+
+
+def parse_and_convert_line(line: str) -> str:
+    for f in [parse_regular_variable, parse_rehashing_variable, parse_add_variable]:
+        parsed = f(line)
+
+        if parsed is not None:
+            return parsed
+
+    else:
+        return line
+
+
+def make_irc_section():
+    return textwrap.dedent(
+    """
+    {{ if (contains .Env "ENABLE_IRC") -}}
+    // special single-server IRC configuration, suitable for our Docker deployment
+    // setting ENABLE_IRC to some value will be sufficient in most cases
+    if (= $rehashing 0) [
+        ircfilter {{ default .Env.IRC_FILTER "1" }} // defines the way the colour-to-irc filter works; 0 = off, "1" = convert, 2 = strip
+
+        ircaddrelay ircrelay {{ default .Env.IRC_RELAY_HOSTNAME "localhost" }} {{ default .Env.IRC_RELAY_PORT "6667" }} {{ default .Env.IRC_RELAY_NICK "re-server" }}
+
+        {{ if (contains .Env "IRC_BIND_ADDRESS") -}}
+        ircbind ircrelay {{ .Env.IRC_BIND_ADDRESS }} // use this only if you need to bind to a specific address, eg. multihomed machines
+        {{ end -}}
+
+        {{ if (contains .Env "IRC_SERVER_PASS" ) -}}
+        ircpass ircrelay {{ .Env.IRC_SERVER_PASS }} // some networks can use the PASS field to identify to nickserv
+        {{ end -}}
+
+        {{ if (contains .Env "IRC_CHANNELS") -}}
+        {{ range $e := ( split .Env.IRC_CHANNELS "," ) -}}
+        ircaddchan ircrelay "{{ $e }}"
+        ircrelaychan ircrelay "{{ $e }}" 3
+        {{ end -}}
+        {{ end -}}
+
+        ircconnect ircrelay // and tell it to connect!
+    ]
+    {{ end -}}
+    """
+    )
+
+
+def make_additional_vars_section():
+    text = textwrap.dedent(
+        """
+        {{ if (contains .Env "ADDITIONAL_VARS") -}}
+        // additional variables
+        {{ range $e := (split .Env.ADDITIONAL_VARS ";") -}}
+        {{ $a := (split $e "=") -}}
+        {{ index $a 0 }} {{ index $a 1 }}
+        {{ end -}}
+        {{ end -}}
+
+        {{ if (contains .Env "SV_DUELMAXQUEUED") -}}
+        sv_duelmaxqueued "{{ .Env.SV_DUELMAXQUEUED }}"
+        {{ end -}}
+        """
+    )
+
+    for i in ["duelmaxqueued", "teamneutralcolour"]:
+        pass
+        text += textwrap.dedent(
+            """
+            {{{{ if (contains .Env "SV_{upper}") -}}}}
+            sv_{lower} "{{{{ .Env.SV_{upper} }}}}"
+            {{{{ end -}}}}
+            """.format(lower=i, upper=i.upper())
+        )
+
+    return text
+
+
+def main():
+    with open(sys.argv[1]) as f:
+        lines = f.read().splitlines()
+
+    for line in lines:
+        print(parse_and_convert_line(line))
+
+    print(make_irc_section())
+    print(make_additional_vars_section())
+
+
+if __name__ == "__main__":
+    try:
+        sys.exit(main())
+    except BrokenPipeError:
+        pass

docker/serverip.patch

@@ -0,0 +1,20 @@
+diff --git a/src/engine/server.cpp b/src/engine/server.cpp
+index a8530e43..89e63f4f 100644
+--- a/src/engine/server.cpp
++++ b/src/engine/server.cpp
+@@ -1329,6 +1329,7 @@ int setupserversockets()
+     if(!servertype || (serverhost && pongsock != ENET_SOCKET_NULL)) return servertype;
+
+     ENetAddress address = { ENET_HOST_ANY, enet_uint16(serverport) };
++#if 0
+     if(*serverip)
+     {
+         if(enet_address_set_host(&address, serverip) < 0)
+@@ -1338,6 +1339,7 @@ int setupserversockets()
+         }
+         else serveraddress.host = address.host;
+     }
++#endif
+
+     if(!serverhost)
+     {