commit 48993f0e4d35533239256be2502d8710671b693f
Author: Jack Jackson <scubbojj@gmail.com>
Date:   Fri Aug 19 16:51:47 2022 -0700

    First commit

diff --git a/Dockerfile b/Dockerfile
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--- /dev/null
+++ b/Dockerfile
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+FROM debian:buster
+
+######
+## Install cloudflared tool
+######
+
+# Instructions from https://pkg.cloudflare.com/
+RUN apt update && apt -y upgrade
+# These two utilities are required but are (understandably) not listed
+# in pkg.cloudflare.com's instructions
+RUN apt install -y curl ca-certificates
+# This utility is required for installation of yq - but we put it earlier
+# to maximize build cache hits
+RUN apt install -y wget
+
+RUN mkdir -p --mode=0755 /usr/share/keyrings
+RUN curl -fsSL https://pkg.cloudflare.com/cloudflare-main.gpg\
+    | tee /usr/share/keyrings/cloudflare-main.gpg >/dev/null
+# Do not try to line-break in the middle of the quoted string!
+RUN echo 'deb [signed-by=/usr/share/keyrings/cloudflare-main.gpg] https://pkg.cloudflare.com/cloudflared buster main' \
+    | tee /etc/apt/sources.list.d/cloudflared.list
+
+RUN apt update && apt install cloudflared
+
+######
+## Install yq (for parsing YAML)
+######
+
+# https://github.com/mikefarah/yq - I tried switching to `curl -o -` but that gave no output?
+RUN wget https://github.com/mikefarah/yq/releases/download/v4.18.1/yq_linux_arm64.tar.gz -O - 2>/dev/null |\
+  tar xz && mv yq_linux_arm64 /usr/bin/yq
+
+######
+## Install own script
+######
+
+COPY dns_update.sh .
diff --git a/dns_update.sh b/dns_update.sh
new file mode 100755
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--- /dev/null
+++ b/dns_update.sh
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+#!/bin/sh
+
+# First argument is cloudflared config file
+# TODO - make this optional, and check standard locations if absent.
+# Not doing it now because that would require me to remember how to
+# do named arguments with bash (I think it's `getopt`?), and ain't
+# nobody got time for that.
+if [ $# -lt 1 ]; then
+  echo "Requires an argument pointing to the config file";
+  exit 1;
+fi
+CONFIG_FILE_LOCATION=$1
+if [ ! -f $CONFIG_FILE_LOCATION ]; then
+  echo "File \"$CONFIG_FILE_LOCATION\" does not exist";
+  exit 1;
+fi
+
+# Second argument is "root domain".
+# If set, only try to update DNS for names that are subdomains of this domain.
+# If not set, try to update all names
+if [ $# -gt 1 ]; then
+  ROOT_DOMAIN=$2;
+  yq ".ingress[].hostname | select(. != null) | select (. == \"*$ROOT_DOMAIN\")" $CONFIG_FILE_LOCATION | xargs -I {} echo "Would process {}";
+else
+  yq '.ingress[].hostname | select(. != null)' $CONFIG_FILE_LOCATION | xargs -I {} echo "Would process {}";
+fi
+