devcontainer: add doc, user to match host machine, and scripts to build/start

ops/devcontainer/Dockerfile

@@ -2,7 +2,20 @@
 
 FROM alpine:3.22
 
-RUN apk add build-base git go sqlite shellcheck curl jq bash docker
+RUN apk add build-base git go sqlite shellcheck curl jq sudo bash docker
+
+# Busybox `less` doesn't appear to support colors (makes git diff lose color)
+RUN apk add less
 
 RUN curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b /usr/local/bin v2.0.2
 RUN GOBIN=/usr/local/bin go install git.offline-twitter.com/offline-labs/gocheckout@v0.0.2
+
+# Create a user in the container with the same UID as on the host machine, to avoid ownership conflicts.
+# The user gets sudo of course.
+ARG USERNAME
+ARG UID
+ARG GID
+RUN addgroup -g ${GID} ${USERNAME}
+RUN adduser -D -u ${UID} -G ${USERNAME} ${USERNAME}
+RUN echo "${USERNAME} ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/${USERNAME}
+USER ${USERNAME}

ops/devcontainer/build.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+SCRIPT_PATH=$(cd "$(dirname "$0")" && pwd)
+
+sudo docker build  \
+    --build-arg USERNAME="$(whoami)" \
+    --build-arg UID="$(id -u)" \
+    --build-arg GID="$(id -g)" \
+    -t gas "$SCRIPT_PATH"

ops/devcontainer/start.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+sudo docker run --rm -it \
+    -v "$(pwd)":/code \
+    -v "$(go env GOCACHE):/gocache-vol" \
+    -e GOCACHE=/gocache-vol \
+    -v "$(go env GOMODCACHE):/gocache-vol/mod-cache" \
+    -e GOMODCACHE=/gocache-vol/mod-cache \
+    -e GOLANGCI_LINT_CACHE=/gocache-vol/lint-cache \
+    --workdir /code \
+    --net host \
+    gas