Fix docker-run-release

This adds Dockerfile.release and fix the docker-run-release make target to work using the image built from it. Setting docker-run --user did not actually work for me due to some git-and-ssh-related operations failing with `No user exists for uid` errors.

Author: mumoshu

.dockerignore

@@ -0,0 +1,2 @@
+# Ignore everything
+*

Dockerfile.release

@@ -0,0 +1,23 @@
+FROM golang:1.19.8
+
+# See https://github.com/cli/cli/blob/trunk/docs/install_linux.md#debian-ubuntu-linux-raspberry-pi-os-apt
+# for the latest gh install instructions when the below didn't work
+
+RUN type -p curl >/dev/null || (apt update && apt install curl -y)
+
+RUN curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg \
+    && chmod go+r /usr/share/keyrings/githubcli-archive-keyring.gpg \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/githubcli-archive-keyring.gpg] https://cli.github.com/packages stable main" | tee /etc/apt/sources.list.d/github-cli.list > /dev/null \
+    && apt update \
+    && apt install gh -y
+
+ARG HELM_DIFF_UID
+
+RUN adduser \
+  --gecos "Helm Diff" \
+  --disabled-password \
+  -u "$HELM_DIFF_UID" \
+  helm-diff-releaser \
+  --shell /bin/sh
+
+USER helm-diff-releaser

Makefile

@@ -54,11 +54,15 @@ docker-run-release:
 	# needed to avoid "failed to initialize build cache at /.cache/go-build: mkdir /.cache: permission denied"
 	mkdir -p docker-run-release-cache
 	# uid needs to be set to avoid "error obtaining VCS status: exit status 128"
-	docker run --user $(shell id -u) -it --rm -e GITHUB_TOKEN \
+	# Also, there needs to be a valid Linux user with the uid in the container-
+	# otherwise git-push will fail.
+	docker build -t helm-diff-release -f Dockerfile.release \
+	  --build-arg HELM_DIFF_UID=$(shell id -u) --load .
+	docker run -it --rm -e GITHUB_TOKEN \
 	-v ${SSH_AUTH_SOCK}:/tmp/ssh-agent.sock -e SSH_AUTH_SOCK=/tmp/ssh-agent.sock \
 	-v $(shell pwd):$(pkg) \
 	-v $(shell pwd)/docker-run-release-cache:/.cache \
-	-w $(pkg) golang:1.19.8 make bootstrap release
+	-w $(pkg) helm-diff-release make bootstrap release
 
 .PHONY: dist
 dist: export COPYFILE_DISABLE=1 #teach OSX tar to not put ._* files in tar archive