Add Dockerfile for building p2p riot

$ docker build -t dendritejs -f DendriteJS.Dockerfile .
$ docker run --rm -p 8090:80 dendritejs

build/docker/DendriteJS.Dockerfile

@@ -0,0 +1,112 @@
+# This dockerfile will build dendritejs and hook it up to riot-web, build that then dump the
+# resulting HTML/JS onto an nginx container for hosting. It requires no specific build context
+# as it pulls archives straight from github branches.
+FROM golang:1.13.7-alpine3.11 AS gobuild
+
+# TODO: This does nothing currently ;)
+# or /dns4/rendezvous.matrix.org/tcp/8443/wss/p2p-websocket-star/
+# or whatever you want!
+ENV RENDEZVOUS_SERVER=/ip4/127.0.0.1/tcp/9090/ws/p2p-websocket-star/
+
+# Download and build dendrite
+WORKDIR /build
+ADD https://github.com/matrix-org/dendrite/archive/master.tar.gz /build/master.tar.gz
+RUN tar xvfz master.tar.gz
+WORKDIR /build/dendrite-master
+RUN GOOS=js GOARCH=wasm go build -o main.wasm ./cmd/dendritejs
+
+
+FROM node:14-stretch AS jsbuild
+# apparently some deps require python
+RUN apt-get update && apt-get -y install python
+
+# Download riot-web and libp2p repos
+WORKDIR /build
+ADD https://github.com/matrix-org/go-http-js-libp2p/archive/master.tar.gz /build/libp2p.tar.gz
+RUN tar xvfz libp2p.tar.gz
+ADD https://github.com/vector-im/riot-web/archive/matthew/p2p.tar.gz /build/p2p.tar.gz
+RUN tar xvfz p2p.tar.gz
+
+# Install deps for riot-web, symlink in libp2p repo and build that too
+WORKDIR /build/riot-web-matthew-p2p
+RUN yarn install
+RUN ln -s /build/go-http-js-libp2p-master /build/riot-web-matthew-p2p/node_modules/go-http-js-libp2p
+RUN (cd node_modules/go-http-js-libp2p && yarn install)
+COPY --from=gobuild /build/dendrite-master/main.wasm ./src/vector/dendrite.wasm
+# build it all
+RUN yarn build:p2p
+
+SHELL ["/bin/bash", "-c"]
+RUN echo $'\ 
+{ \n\
+    "default_server_config": { \n\
+        "m.homeserver": { \n\
+            "base_url": "https://p2p.riot.im", \n\
+            "server_name": "p2p.riot.im" \n\
+        }, \n\
+        "m.identity_server": { \n\
+            "base_url": "https://vector.im" \n\
+        } \n\
+    }, \n\
+    "disable_custom_urls": false, \n\
+    "disable_guests": true, \n\
+    "disable_login_language_selector": false, \n\
+    "disable_3pid_login": true, \n\
+    "brand": "Riot", \n\
+    "integrations_ui_url": "https://scalar.vector.im/", \n\
+    "integrations_rest_url": "https://scalar.vector.im/api", \n\
+    "integrations_widgets_urls": [ \n\
+        "https://scalar.vector.im/_matrix/integrations/v1", \n\
+        "https://scalar.vector.im/api", \n\
+        "https://scalar-staging.vector.im/_matrix/integrations/v1", \n\
+        "https://scalar-staging.vector.im/api", \n\
+        "https://scalar-staging.riot.im/scalar/api" \n\
+    ], \n\
+    "integrations_jitsi_widget_url": "https://scalar.vector.im/api/widgets/jitsi.html", \n\
+    "bug_report_endpoint_url": "https://riot.im/bugreports/submit", \n\
+    "defaultCountryCode": "GB", \n\
+    "showLabsSettings": false, \n\
+    "features": { \n\
+        "feature_pinning": "labs", \n\
+        "feature_custom_status": "labs", \n\
+        "feature_custom_tags": "labs", \n\
+        "feature_state_counters": "labs" \n\
+    }, \n\
+    "default_federate": true, \n\
+    "default_theme": "light", \n\
+    "roomDirectory": { \n\
+        "servers": [ \n\
+            "matrix.org" \n\
+        ] \n\
+    }, \n\
+    "welcomeUserId": "", \n\
+    "piwik": { \n\
+        "url": "https://piwik.riot.im/", \n\
+        "whitelistedHSUrls": ["https://matrix.org"], \n\
+        "whitelistedISUrls": ["https://vector.im", "https://matrix.org"], \n\
+        "siteId": 1 \n\
+    }, \n\
+    "enable_presence_by_hs_url": { \n\
+        "https://matrix.org": false, \n\
+        "https://matrix-client.matrix.org": false \n\
+    }, \n\
+    "settingDefaults": { \n\
+        "breadcrumbs": true \n\
+    } \n\
+}' > webapp/config.json
+
+FROM nginx
+# Add "Service-Worker-Allowed: /" header so the worker can sniff traffic on this domain rather
+# than just the path this gets hosted under. NB this newline echo syntax only works on bash.
+SHELL ["/bin/bash", "-c"]
+RUN echo $'\
+server { \n\
+    listen 80; \n\
+    add_header \'Service-Worker-Allowed\' \'/\'; \n\
+    location / { \n\
+        root   /usr/share/nginx/html; \n\
+        index  index.html index.htm; \n\
+    } \n\
+}' > /etc/nginx/conf.d/default.conf
+RUN sed -i 's/}/    application\/wasm  wasm;\n}/g' /etc/nginx/mime.types
+COPY --from=jsbuild /build/riot-web-matthew-p2p/webapp /usr/share/nginx/html